SC IEN

CE

United States

Environmental Protection

Agency

EPA/600/R-09/012 | February 2009 | www.epa.gov/ord

Decontamination of Toxic Industrial 

Chemicals and Chemical Warfare 

Agents on Building Materials Using 

Chlorine Dioxide Fumigant and 

Liquid Oxidant Technologies

TECHNOLOGY INVESTIGATION REPORT

Office of Research and Development

National Homeland Security Research Center
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EPA/600/R-09/012 | February 2009 | www.epa.gov/ord

TECHNOLOGY INVESTIGATION REPORT

Decontamination of Toxic Industrial 

Chemicals and Chemical Warfare Agents 

On Building Materials Using Chlorine 

Dioxide Fumigant and Liquid Oxidant 

Technologies

By

James Rogers, Timothy Hayes, Donald Kenny, Ian MacGregor, Karen Tracy, 

Robert Krile, Marcia Nishioka, Michael Taylor, Karen Riggs, and Harry Stone 

Battelle

505 King Avenue 

Columbus, OH 43201

Shawn Ryan

Task Order Project Officer

National Homeland Security Research Center 

Office of Research and Development

U.S. Environmental Protection Agency 

Mail Code E343-06 

Research Triangle Park, NC 27711
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ERRATA Sheet

For the document: Decontamination of Toxic Industrial Chemicals and Chemical Warfare Agents 

On Building Materials Using Chlorine Dioxide Fumigant and Liquid Oxidant Technologies 

(EPA/600/R-09/012) February 2009

Updated 07/2009 with the following modifications:

• Table 4-13 (Page 27): The numbers in the rightmost column were made bold to correspond with 

footnote c [Decontamination efficacy shown in bold indicates a statistically significant difference 

in recovery with and without decontamination (p ≤ 0.05)]. 

• Table 4-19 (Page 34): The numbers in the rightmost column were made bold to correspond 

with footnote a [Calculated using Eq (8); values given in bold are statistically significant].

• Page 31(Left Column, 2nd paragraph): 100% bleach (6% hypochlorite) was modified to read 

10% bleach (0.6% hypochlorite).
v

Notice

The U.S. Environmental Protection Agency (EPA), through the Office of Research and 

Development’s (ORD) National Homeland Security Research Center (NHSRC), funded and 

managed this technology investigation through a Blanket Purchase Agreement under General 

Services Administration contract number GS23F0011L-3 with Battelle. This report has been peer 

and administratively reviewed and has been approved for publication as an EPA document. Mention 

of trade names or commercial products does not constitute endorsement or recommendation for use 

of a specific product.
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Foreword

The EPA is charged by Congress with protecting the nation’s air, water, and land resources. Under 

a mandate of national environmental laws, the Agency strives to formulate and implement actions 

leading to a compatible balance between human activities and the ability of natural systems to support 

and nurture life. To meet this mandate, ORD provides data and science support that can be used 

to solve environmental problems and to build the scientific knowledge base needed to manage our 

ecological resources wisely, to understand how pollutants affect our health, and to prevent or reduce 

environmental risks.

In September 2002, EPA announced the formation of the NHSRC. The NHSRC is part of the ORD; it 

manages, coordinates, and supports a variety of research and technical assistance efforts. These efforts 

are designed to provide appropriate, affordable, effective, and validated technologies and methods for 

addressing risks posed by chemical, biological, and radiological terrorist attacks. Research focuses on 

enhancing our ability to detect, contain, and clean up in the event of such attacks.

NHSRC’s team of world renowned scientists and engineers is dedicated to understanding the terrorist 

threat, communicating the risks, and mitigating the results of attacks. Guided by the roadmap set forth 

in EPA’s Strategic Plan for Homeland Security, NHSRC ensures rapid production and distribution of 

security-related products.

The NHSRC has created the Technology Testing and Evaluation Program (TTEP) in an effort to 

provide reliable information regarding the performance of homeland security related technologies. 

TTEP provides independent, quality assured performance information that is useful to decision makers 

in purchasing or applying the tested technologies. It provides potential users with unbiased, thirdparty information that can supplement vendor-provided information. Stakeholder involvement ensures 

that user needs and perspectives are incorporated into the test design so that useful performance 

information is produced for each of the tested technologies. The technology categories of interest 

include detection and monitoring, water treatment, air purification, decontamination, and computer 

modeling tools for use by those responsible for protecting buildings, drinking water supplies and 

infrastructure, and for decontaminating structures and the outdoor environment.

The investigation reported herein was conducted by Battelle, under the direction of NHSRC, as 

part of TTEP. Information on NHSRC and TTEP can be found at http://www.epa.gov/nhsrc.
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Acknowledgments

The authors wish to acknowledge the support of all those who helped plan and conduct the 

investigation, analyze the data, and prepare this report. We also would like to thank Lawrence 

Kaelin (EPA National Decontamination Team), David Mickunas (EPA Environmental Response 

Team), Donna Getty (Lockheed-Martin), Emily Snyder (EPA/ORD/NHSRC), and Joseph Wood 

(EPA/ORD/NHSRC) for reviewing this report.
viii

Contents

Notice ...................................................................................................................................................v

Foreword .............................................................................................................................................vi

Acknowledgments ..............................................................................................................................vii

Abbreviations/Acronyms ...................................................................................................................xiii

Executive Summary ...........................................................................................................................xiv

1.0 Introduction ..................................................................................................................................1

 1.1 Objectives .................................................................................................................................1

 1.2 Approach ..................................................................................................................................1

 1.3 Experimental Design ................................................................................................................2

 1.4 Definitions of Coupon Treatments ...........................................................................................3

2.0 Methods .........................................................................................................................................5

 2.1 ClO2 Fumigant Decontamination Technology Used with TICs and CWAs .............................5

 2.1.1 Sabre Technical Services ClO2 Generator ........................................................................5

 2.2.2 Measurement in the Test Chamber Atmosphere ..............................................................5

 2.2 Liquid Decontamination Technologies Used with CWAs ........................................................5

 2.2.1 Liquid Decontamination Solutions Tested .......................................................................5

 2.2.2 Liquid Decontamination Test System ..............................................................................6

 2.3 TICs ..........................................................................................................................................6

 2.3.1 Test Chamber for Fumigant Decontamination Tests........................................................6

 2.3.2 Building Materials ...........................................................................................................7

 2.3.3 Sequence of Testing .........................................................................................................7

 2.3.4 Source of TICs .................................................................................................................7

 2.3.5 Application of TICs to Test Coupons ...............................................................................8

 2.3.6 Extraction Method for TICs from Test Coupons .............................................................8

 2.3.7 Air Sampling and Analysis of TICs Using Tenax® Sorbent Air Sampling Tubes ............9

 2.3.8 Analysis Method for TICs................................................................................................9

 2.3.9 Calculation of TIC Recovery Efficiency, Percent Recovery, and 

 Decontamination Efficacy ...............................................................................................10

 2.4 CWAs .......................................................................................................................................11

 2.4.1 Test Chamber for Fumigant Decontamination Tests........................................................11

 2.4.2 Test Chamber for Liquid Decontamination Tests ............................................................12

 2.4.3 Building Materials ...........................................................................................................12

 2.4.4 Sequence of Testing .........................................................................................................12

 2.4.5 CWAs and Surrogate Recovery Standard ........................................................................13

 2.4.6 Application of CWAs to Test Coupons ............................................................................13

 2.4.7 Extraction Method for CWAs ..........................................................................................14

 2.4.8 Analysis Method for CWAs .............................................................................................14

 2.4.9 Calculation of CWA Recovery Efficiency, Percent Recovery, and 

 Decontamination Efficacy ...............................................................................................14

 2.5 Qualitative Evaluation of the Impact of ClO2

 Fumigation on Building Materials .............14
ix

3.0 Quality Assurance/Quality Control ............................................................................................15

 3.1 PE Audit ...................................................................................................................................15

 3.2 Technical Systems Audit ..........................................................................................................15

 3.3 Data Quality Audit....................................................................................................................16

 3.4 QA/QC Reporting ....................................................................................................................16

 3.5 Deviations from Test/QA Plan..................................................................................................16

4.0 Results ...........................................................................................................................................17

 4.1 Results for Fumigant ClO2

 Decontamination of TICs..............................................................17

 4.1.1 Analytical Method Development Results ........................................................................17

 4.1.2 Environmental Conditions during Decontamination Tests ..............................................17

 4.1.3 Recovery over Time of TICs on Building Materials With and Without Sabre 

 ClO2 Fumigant Decontamination ....................................................................................18

 4.1.4 Statistical Analysis of Recovery Trends and Decontamination Efficacy .........................19

 4.1.5 TICs on Laboratory, Handling, and Procedural Blank Coupons .....................................22

 4.1.6 TICs in Chamber Air .......................................................................................................23

 4.1.7 Detection of Oxidized Malathion Product on Coupons ...................................................23

 4.1.8 Condition of ClO2

-Treated Coupons after Six Months ....................................................24

 4.2 Results for Fumigant ClO2 Decontamination of CWAs ...........................................................24

Thsi page intentionally blank. 4.2.1 Analytical Method Results ...............................................................................................24

 4.2.2 Recovery over Time of CWAs on Building Materials With and Without Sabre 

 ClO2 Fumigant Decontamination .....................................................................................24

 4.2.3 Statistical Analysis of Recovery Trends and Fumigant Decontamination Efficacy ........26

 4.2.4 CWAs on Laboratory and Procedural Blank Coupons ....................................................30

 4.2.5 Concentration of ClO2 in Test Chambers .........................................................................30

 4.3 Results for Liquid Decontamination of CWAs.........................................................................31

 4.3.1 Recovery of CWAs from Liquid Decontamination Solutions .........................................31

 4.3.2 Recovery over Time of CWAs on Building Materials With and Without 

 Liquid Bleach Decontamination ......................................................................................31

 4.3.3 Statistical Analysis of Recovery Trends and Liquid Decontamination Efficacy .............34

 4.3.4 CWAs on Laboratory and Procedural Blank Coupons During Liquid 

 Decontamination Tests.....................................................................................................35

5.0 Summary .......................................................................................................................................37

6.0 References .....................................................................................................................................39

7.0 Appendix .......................................................................................................................................41
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Figures

Figure 2-1. Frontal (left) and Overhead (right) Views of Test Chamber Used for 

 Decontamination Test of TICs ..........................................................................................7

Figure 4-1. Statistically Modeled Percent Recovery Data for DMMP on Coupons 

 With and Without Sabre ClO2 Fumigant Decontamination .............................................21

Figure 4-2. Statistically Modeled Percent Recovery Data for Malathion on Coupons 

 With and Without Sabre ClO2 Fumigant Decontamination .............................................21

Figure 4-3. Percent Oxidation of Malathion to Maloxon by Coupon Type and ClO2 Dosage ............24

Figure 4-4. GB Recovery (%) on Coupons With and Without Sabre ClO2 Fumigant 

 Decontamination ...............................................................................................................28

Figure 4-5. TGD Recovery (%) on Coupons With and Without Sabre ClO2 Fumigant

 Decontamination ...............................................................................................................28

Figure 4-6. VX Recovery (%) on Coupons With and Without Sabre ClO2 Fumigant 

 Decontamination ...............................................................................................................29

Figure 4-7. Statistical Analysis Results of VX Decontamination with Liquid ClO2 ...........................35
xi

Tables

Table ES-1. Mean Percent Recovery of TICs and CWAs on Building Materials With and Without .

 ClO2 Fumigation (Normalized to Recovery at Time 0) ....................................................xiv

Table ES-2. Percent Recovery of CWAs Spiked Directly into Decontamination Solutions 

 With and Without Neutralization ......................................................................................xiv

Table ES-3. Percent Recovery of CWAs from Building Materials Following 

 Various Treatments ...........................................................................................................xv

Table 1-1. Building Materials Used in Decontamination Investigation...............................................2

Table 1-2. Target Parameters for Decontamination Testing .................................................................3

Table 1-3. Coupon Treatments .............................................................................................................3

Table 1-4. Selected TICs and CWAs with Analytical Measurement Parameters .................................4

Table 2-1. Types of Coupons Used in the TIC Fumigation Investigation ...........................................7

Table 2-2. Source of TICs and PE Audit Standards .............................................................................8

Table 2-3. Solvent Evaporation Times for TICs Spiked on Various Building Materials .....................8

Table 2-4. Extraction and Concentration Techniques Used for TICs ..................................................8

Table 2-5. GC and MS Conditions for Analysis of DMMP in Air Samples ........................................9

Table 2-6. GC and MS Conditions for TIC Analyses ..........................................................................9

Table 2-7. GC Retention Times and Monitored Ions for TIC Analyses ..............................................10

Table 2-8. Building Material Test Coupon Characteristics for CWA Decontamination Tests .............12

Table 2-9. Source of CWAs and SRS ...................................................................................................13

Table 2-10. Mass of CWA Applied to Building Material Coupons .....................................................13

Table 2-11. GC/FPD Conditions for CWA Analyses ...........................................................................14

Table 2-12. GC Retention Times for CWA Analyses ...........................................................................14

Table 3-1. TIC PE Audit Results ..........................................................................................................15

Table 3-2. CWA PE Audit Results .......................................................................................................15

Table 4-1. Extraction Efficiencies of TICs and Matched SRSs from Building Materials ...................17

Table 4-2. MDLs for TICs ...................................................................................................................17

Table 4-3. Mean Temperature, RH, ClO2

 Concentration, and Air Velocity during TIC

 Decontamination Tests ........................................................................................................18

Table 4-4. Comparison of Mean Percent Recovery of DMMP with Different Chamber 

 Air Exchange Rates .............................................................................................................18

Table 4-5. Mean Recovery of TICs from Building Materials over Time With and 

 Without Sabre ClO2

 Fumigant Decontamination ................................................................19

Table 4-6. Statistically Modeled, Eq (11), Percent Recovery of TICs With and 

 Without Sabre ClO2 Fumigant Decontamination and Decontamination Efficacy ..............20

Table 4-7. Mean TIC Levels on Laboratory, Handling, and Procedural Blank Coupons ....................22

Table 4-8. Mean Concentration of TICs in Test Chamber Air .............................................................23

Table 4-9. Mean Mass of Malathion Oxidized to Maloxon by Coupon Type and ClO2 CT ................23

Table 4-10. Recovery of CWAs and SRS from Building Materials.....................................................25

Table 4-11.MDLs for CWAs ................................................................................................................25

Table 4-12. Average Recovery of CWAs from Building Materials over Time With and 

 Without Sabre ClO2 Fumigant Decontamination ..............................................................25
xii

Table 4-13. Statistically Modeled, Eq (11), Percent Recovery of CWAs With and 

 Without Sabre ClO2 Fumigant Decontamination and Decontamination Efficacy .............27

Table 4-14. Comparison of Mean CWA Levels on Laboratory and Procedural Blank Coupons ........30

Table 4-15. Mean Concentration of ClO2 in Test Chamber for CWA Decontamination Tests ............30

Table 4-16. Mean Recovery of CWAs and SRS from Liquid Decontamination Solutions .................31

Table 4-17. Mean Recovery of CWAs from Building Materials After Various 

 Treatments as Percent of Mass Applied ............................................................................32

Table 4-18. Mean Recovery of CWAs from Building Materials After Various 

 Treatments as Percent of T0 Recovery..............................................................................33

Table 4-19. Statistically Modeled Percent, Eq (11), Recovery of VX With and Without 

 Liquid ClO2 Decontamination and Decontamination Efficacy 

 (Compared to Recovery from Acidified Water) ...............................................................34

Table 4-20. CWA Levels on Laboratory and Procedural Blank Coupons with Bleach 

 Decontamination ...............................................................................................................35

Table 4-21. VX Levels on Procedural Blank Coupons with Liquid ClO2 Decontamination ...............36

Table 5-1. Summarization of Percent Recovery With and Without Decontamination 

 Technologies, and Decontamination Efficacy for TICs and CWAs ....................................37

Table 5-2. Mean Recovery of CWAs Directly Spiked into Liquid Decontamination Solutions .........38

Table A-1. Normalized Mean Recovery of TICs on Building Materials over Time With 

 and Without Sabre ClO2 Fumigant Decontamination ........................................................41

Table A-2. Normalized Mean Recovery of CWAs on Building Materials over Time With 

 and Without Sabre ClO2 Fumigant Decontamination ........................................................42

Table A-3. Normalized Mean Recovery of VX on Building Materials With and 

 Without Liquid ClO2 Decontamination ..............................................................................42
xiii

Abbreviations/Acronyms

ANOVA analysis of variance

BBRC Battelle Biomedical Research Center 

ClO- hypochlorite ion

ClO2 chlorine dioxide 

cm centimeter(s)

CWA(s) chemical warfare agent(s)

CT concentration x contact time

DEEP diethyl ethylphosphonate

DIMP diisopropyl methylphosphonate

DMMP dimethyl methylphosphonate

EPA U.S. Environmental Protection Agency

Eq equation

FPD flame photometric detection 

ft feet

g gram(s)

GB sarin

GC gas chromatograph; gas chromatography

GC/FPD gas chromatography/flame photometric detection

GC/MS gas chromatography/mass spectrometry

GD soman

h hour(s)

IS internal standard

KD Kuderna-Danish 

HVAC heating, ventilation, and air conditioning

L liter(s)

m meter(s)

M molarity; moles/liter 

MDL method detection limit

MFC mass flow controller

μg microgram(s)

μL microliter(s)

μm micrometer(s)

m meter(s)

mg milligram(s)

min minute(s)

mL milliliter(s)

mm millimeter(s)

MS mass spectrometer

m/z mass-to-charge ratio (unitless)

n number of samples

N normal

ND not detected

NT not tested

NHSRC National Homeland Security Research Center

NIST National Institute of Standards and Technology

ORD Office of Research and Development 

PE performance evaluation

ppm parts per million

QA quality assurance

QC quality control

QMP quality management plan

RH relative humidity

SD standard deviation

sec second(s)

SRS(s) surrogate recovery standard(s)

STS sodium thiosulfate

TBP tributyl phosphate

TGD thickened soman

TIC(s) toxic industrial chemical(s)

TD thermal desorption

TSA technical systems audit

TTEP Technology Testing and Evaluation Program 
xiv

Executive Summary

The purpose of this effort was to determine the effectiveness 

of several decontamination technologies against both 

toxic industrial chemicals (TICs) and chemical warfare 

agents (CWAs) on standard building materials was 

recently completed. Prior to the test design for this effort, 

an assessment of the state of the knowledge for TIC and 

CWA decontamination on complex building materials 

was performed. Following this assessment, combinations 

of TICs, CWAs, building materials, decontamination 

technologies and conditions were selected for the study. The 

first phase of the testing included a study of the persistence 

of the TICs and CWAs on the materials at typical ambient 

conditions[1]. Decontamination studies were only performed 

with combinations of agents and materials in which 

persistence was determined sufficient in order to observe 

an impact of the decontamination treatment. The TICs that 

were used in this testing included malathion and dimethyl 

methylphosphonate (DMMP). These TICs were chosen for a 

combination of two reason: (1) for their properties as TICs, 

and (2) their potential as simulants for VX and sarin (GB), 

respectively, due to the similarities in key structural elements. 

The CWAs that were tested included sarin, thickened soman 

(TGD), and VX. The technologies investigated included 

fumigation with chlorine dioxide (ClO2) and soaking in liquid 

oxidants. 

Fumigation at 80% relative humidity (RH) and 3000 parts 

per million (ppm) ClO2 used a commercially available system 

manufactured by Sabre, Inc. This Sabre technology was 

tested against:

• Malathion on carpet and laminate materials 

• DMMP on carpet and ceiling tile 

• GB on carpet 

• TGD on carpet, laminate, and metal ductwork

• VX on carpet, laminate, and metal ductwork. 

The liquid oxidants included diluted commercial bleach 

(diluted 1:10 with water; 5000 ppm hypochlorite ion [ClO-

]) 

and an aqueous solution of 3000 ppm ClO2. Aqueous bleach 

was tested against: 

• GB on carpet 

• TGD on carpet, laminate, and metal ductwork

• VX on carpet, laminate, and metal ductwork.

The aqueous ClO2 solution was tested against VX on carpet, 

laminate, and metal ductwork.

This decontamination research addressed the following 

questions:

• What is the percent recovery of TICs and CWAs exposed 

to the specified treatments?

• What is the relative recovery (decontamination efficacy) 

of TICs and CWAs in the presence of the decontamination 

technology compared to a similarly matched control?

• Is there visible surface damage to building materials as a 

result of the decontamination technology?

The above matrix of test agent and building material coupons 

reflects the results of the persistence study that preceded 

this decontamination study. In that prior testing, persistence 

was found to vary widely, from as low as 0% GB recovered 

from laminate after five minutes (min) up to 85% malathion 

recovered from carpet after seven days.[1] While there was 

evidence for complex interactions between test compound 

and substrate, persistence could mostly be predicted and 

explained on the basis of vapor pressure and hydrolysis rate 

of the compounds, and the type of the building material. 

Hence, only combinations of chemicals and materials in 

which the agent was persistent enough to determine the effect 

of the decontamination were used, and some substitutions 

in materials were made in some cases to provide longer 

persistence (e.g., for DMMP, ceiling tile was used rather than 

laminate). 

Very similar bench-scale testing approaches were used for 

these technology investigations as were utilized for the 

persistence testing. This included liquid spiking of a known 

amount of an individual TIC or CWA onto replicate coupons 

of the building material (five identical coupons each either 

5 square centimeters [cm2] for TICs or 10 cm2 for CWAs 

were utilized). These coupons were allowed to contact the 

decontamination technology for a fixed amount of time up to 

7 hours (h) in a sealed chamber under controlled conditions 

of temperature, RH, and air movement. Each coupon was 

then extracted to measure the amount of TIC or CWA that 

remained on the coupons. These tests used spikes of 500 

micrograms (μg) of TICs onto 5 cm2 coupons, or 1000 μg of 

CWAs onto 10 cm2 coupons, so as to approximate a surface 

loading of 1 g m-2, which is assumed to be a worst-case 

contamination scenario. 

The persistence of these chemicals under conventional 

environmental conditions is highly variable, and in some 

cases the chemicals have limited persistence. For these 

reasons, the fumigant decontamination tests were matched 

with positive control tests of the chemical on the same type 

of building material coupon for the same duration and at the 

same temperature as the decontamination test, so that the 

effectiveness of the decontamination technology could be 

accurately differentiated from other loss mechanisms such as 

volatilization and decomposition unrelated to the fumigation. 

Fumigation with ClO2

 resulted in statistically significant 

efficacy against malathion on both carpet and laminate at 

1, 3, and 7 h exposures; a small, but statistically significant 

efficacy (7.5%) was observed against DMMP only on ceiling 

tile at 7 h. Fumigation with ClO2 resulted in statistically 

significant efficacy >99% against VX on carpet, laminate, 

and ductwork after a 1h exposure; a smaller statistically 

significant efficacy (34% – 62%) was observed against GB 

and TGD on carpet after a 1 h exposure. No statistically 
xv

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significant efficacy of ClO2 fumigation was observed against 

TGB on laminate or ductwork. 

As shown in Tables ES-1 and ES-2, VX was reduced to 

non-detectable levels on all materials with all three of 

the decontamination technologies tested. When VX was 

exposed to high RH only (as a control for the fumigant 

ClO2 decontamination test), the mean recovery was high, 

indicating that the vapor phase ClO2 itself was effective at 

decontaminating the VX. 

Liquid technologies were screened for efficacy in preliminary 

testing in which the CWA was placed into decontamination 

technology and neutralized decontamination technology. 

The CWA was extracted from the solution and analyzed 

to determine the mass of CWA in the extract. The results 

of the tests, shown in Table ES-2, demonstrated that, 

except for GD in bleach, the difference in mean recovery 

between the decontamination technology and neutralized 

decontamination technology was negligible. VX, which 

is persistent on building materials exposed to air, was not 

recovered from neutralized bleach or neutralized ClO2

solutions when extracted within 15 seconds (sec); causes 

were not determined but could include hydrolysis of the 

VX or an ineffective recovery method. In bleach, none of 

the three CWAs were recovered. Only small amounts of GB 

(1%) were recovered after 15 sec in neutralized bleach. There 

was little or no difference between the mean recovery of any 

CWA after 15 sec in neutralized ClO2 or after 1 h exposed to 

ClO2 decontamination; a large percentage (58%) of GD was 

recovered from the ClO2 solution. 

Table ES-3 summarizes the mean percent recovery of 

the TICs and CWAs on different building materials 

following liquid decontamination treatments. The bleach 

decontamination tests were matched with positive controls 

exposed to air. The positive controls used with liquid bleach 

were placed in empty vials. The results in Table ES-3 show 

that in all cases, when compared to untreated coupons, 

the CWA recovered from coupons soaked in bleach were 

significantly lower and in most cases not detected, after 

Table ES-1. Mean Percent Recovery of TICs and CWAs on Building Materials 

With and Without ClO Fumigation (Normalized to Recovery at Time 0) 2

TIC/CWA Material Time (n) Mean Recovery, % of T0 ± SD

Without 

Decontamination

With ClO 2

Fumigation

DMMP Carpet 7 h (n = 5) 16 ± 3 23 ± 4

Ceiling tile 7 h (n = 5) 12 ± 1 8.7 ± 0.3

Malathion Carpet 7 h (n = 5) 87 ± 1 24 ± 2

Laminate 7 h (n = 5) 94 ± 10 0.4 ± 0.2

GB Carpet 4 h (n = 5) 5.7 ± 0.2 3.3 ± 1.0

TGD Carpet 2 h (n = 5) 57 ± 6 36 ± 17

Laminate 2 h (n = 5) 1.3 ± 1.6 0.10 ± 0.11

Ductwork 2 h (n = 5) 5.9 ± 2.6 7.4 ± 9.0

VX Carpet 1 h (n = 5) 105 ± 31 ND, <0.7a

Laminate 1 h (n = 5) 86 ± 8 ND, <0.7

Ductwork 1 h (n = 5) 101± 3 ND, <0.7

a) ND = not detected; method detection limit converted to equivalent recovery value

Table ES-2. Mean Percent Recovery of CWAs Spiked Directly 

into Decontamination Solutions With and Without Neutralization

Solution – Hold Time Before SRS 

Addition and Hexane Extraction

CWA Mean Recovery, 

% of Spike ± SD (n = 3)

GB GD VX

Bleach - 1 h ND, <0.1 ND, <0.1 ND, <0.7

Neutralized bleach - 15 sec 1 ± 0 41 ± 10 ND, <0.7

ClO2 - 1 h 8 ± 2 58 ± 5 ND, <0.7

Neutralized ClO2 - 15 sec 8 ± 1 56 ± 10 ND, <0.7

ND = not detected
xvi

exposures of 10 to 30 min. The positive controls used 

with liquid bleach were placed in empty vials, so that 

apparent decontamination with this solution could not be 

distinguished from other potential loss processes such as 

aqueous hydrolysis. The results shown in Tables ES-2 and 

ES-3 suggest that bleach is effective for decontamination 

of GD/TGD. However, the low recoveries of GB and no 

recovery of VX from the neutralized bleach require caution 

in interpreting these results; based on these data, apparent 

effectiveness cannot be distinguished from other explanations 

of low recoveries such as aqueous hydrolysis or ineffective 

recovery methods. Further research is needed to isolate the 

cause.

The tests with liquid ClO2 decontamination of VX (which is 

unstable in alkaline solutions) were matched with positive 

controls in acidified water to attempt to reduce the hydrolysis 

effects of water for comparison with the decontamination 

effects of ClO2. For VX on carpet and laminate, a statistically 

significant reduction of 86% and 63% was achieved after 

10 min exposure to liquid ClO2; efficacy against VX on 

ductwork was indeterminate.

The ClO2 fumigation was shown to be highly effective 

against VX. In some but not all cases, dependent on the type 

of coupon, ClO2 resulted in statistically significant reductions 

in GB and TGD. 

The TGD levels on the three materials were reduced to very 

low levels (<1% of the initial mass applied to the coupon) 

using liquid bleach; fumigant ClO2 was not as effective as 

liquid bleach in attacking TGD on carpet and ductwork. 

Liquid bleach was effective in removing TGD from the 

surfaces of the building materials. There was no attempt to 

measure TGD in the bleach solution. TGD may have been 

hydrolyzed by the aqueous bleach or effectively solubilized 

by it. 

Similarly, GB was effectively removed from the carpet by 

liquid bleach; however, the investigation did not clarify 

whether this removal was due to volatilization, hydrolysis, 

solubilization, or a combination of these processes. No 

decontamination efficacy was observed for liquid ClO2

against GB or GD in the solution testing; efficacy against VX 

was indeterminate.

No damage or visible change to any of the materials was 

observed comparing extracted laboratory blank coupons 

(not exposed to decontamination) to extracted procedural 

blank coupons (exposed to decontamination) directly after 

decontamination treatment. Materials exposed to the liquid 

decontaminants were not evaluated at subsequent time 

post-decontamination. For ClO2 fumigation, the coupons 

were relatively unchanged after three months, and the carpet 

showed some very minor “bleaching” after six months.

This work demonstrated that there are very simple and 

effective methods for removing toxic chemicals from the 

surfaces of building materials. In some cases the results 

from this investigation could not be used to establish the 

mechanisms and processes involved in removal of the 

chemicals from the surfaces because measurement of the 

residual chemical on the building material surface did not 

indicate whether the chemical was transferred intact to the 

aqueous decontamination solution or whether it was degraded 

or hydrolyzed to another chemical. These types of questions 

may best be answered by direct analyses (e.g., no solvent 

extraction) of the decontamination solutions to verify whether 

intact toxic chemicals or degradation products are present. 

Insofar as this program was designed to evaluate residuals 

on surfaces after decontamination treatments, the goals were 

achieved, and reliable technologies for decontamination were 

identified.

Table ES-3. Mean Percent Recovery of CWAs from Building Materials 

Following Various Treatments

CWA Material Time Mean Recovery, % of Mass Recovered at Time 0 ± SD

Without Decontamination 

(in air in a sealed vial)

With Bleach 

Decontamination

GB Carpet 10 min 93 ± 7 ND, <0.1a

TGD Carpet 10 min 121 ± 33 ND, <0.1

Laminate 10 min 90 ± 10 3.7 ± 1.9

Ductwork 10 min 130 ± 39 3.2 ± 1.9

VX Carpet 30 min 107 ± 7 ND, <0.7

Laminate 30 min 102 ± 6 ND, <0.7

Ductwork 30 min 95 ± 11 ND, <0.7

Without Decontamination 

(in acidified water)b

With ClO (Liquid) 2

Decontamination

VX Carpet 10 min 5.0 ND, <0.7

Laminate 10 min 1.9 ND, <0.7

Ductwork 10 min ND, <0.7 ND, <0.7

a) ND = not detected 

b) Results from ANOVA modeling of recovery data
1

The EPA’s NHSRC is helping to protect human health and the 

environment from adverse impacts resulting from intentional 

acts of terror. With an emphasis on decontamination and 

consequence management, water infrastructure protection, 

and threat and consequence assessment, NHRSC is working 

to develop tools and information that will help detect 

the intentional introduction of chemical, biological or 

radiological contaminants in buildings or water systems, 

contain these contaminants, decontaminate buildings and/or 

water systems, and facilitate the disposal of material resulting 

from cleanups. 

NHSRC’s TTEP works in partnership with recognized testing 

organizations; with stakeholder groups consisting of buyers, 

vendor organizations, and permitters; and with the voluntary 

participation of individual technology developers in carrying 

out performance tests on homeland security technologies. 

The program evaluates the performance of innovative 

homeland security technologies by developing test plans that 

are responsive to the needs of stakeholders, conducting tests, 

collecting and analyzing data, and preparing peer-reviewed 

reports. All investigations are conducted in accordance with 

rigorous quality assurance (QA) protocols to ensure that data 

of known and high quality are generated and that the results 

are defensible. TTEP provides high-quality information that 

is useful to decision makers in purchasing or applying the 

tested technologies. It provides potential users with unbiased, 

third-party information that can supplement vendor-provided 

information. Stakeholder involvement ensures that user needs 

and perspectives are incorporated into the test design so that 

useful performance information is produced for each of the 

tested technologies. 

1.1 Objectives

This testing was conducted to measure the effectiveness 

of different decontamination technologies against two 

representative TICs and three representative CWAs on a 

range of indoor building materials. The recovery (extractable 

mass) of the chemicals with and without the decontamination 

agent was ascertained initially. The effectiveness of the 

decontamination technology was assessed as the statistically 

significant relative recovery of TIC or CWA from building 

material coupons after a specified time period with or without 

contact with the decontamination technology. This approach 

controls for losses due to normal environmental processes 

such as volatilization. 

This decontamination research addressed the following 

questions:

• What is the relative recovery of TICs and CWAs in the 

presence of the decontamination technology compared to 

a similarly matched control?

• What is the percent reduction of TICs and CWAs exposed 

to various treatments?

• What is the decontamination efficacy of the 

decontamination technology for removal of TICs and 

CWAs?

• Is there visible surface damage to building materials as a 

result of the decontamination technology?

1.2 Approach

The general approach developed and utilized for 

decontamination testing was to apply a known amount of 

each TIC or CWA to each of several test coupons of the 

same building material (replicate coupons, identical in size 

and shape) and allow these spiked test coupons to age under 

controlled environmental conditions of temperature and RH, 

either with the decontamination agent or without this agent. 

At specified intervals, replicate test coupons were extracted 

and the extracts were analyzed to determine the amount of 

the TIC or CWA that remained on the test coupon at that 

specific time. 

The overall approach developed and applied for 

decontamination testing of fumigant and liquid 

decontamination technologies was generally the same; 

however, the fumigant technology testing was conducted 

in a sealed chamber whereas the liquid decontamination 

was conducted in individual sealed vials. The fumigant 

technology was applied to both TICs and CWAs; the 

liquid decontamination was applied to only the CWAs. 

The specific details for the methodologies used for 

decontamination testing of TICs and CWAs are 

described in detail in Section 2.0.

1.0

Introduction
2

1.3 Experimental Design 

The chemicals that were selected for use in this investigation 

include: 

TICs

• Malathion

• DMMP

CWAs

• GB

• TGD

• VX.

Table 1-1 specifies the building materials used in this 

decontamination investigation which included industrial 

grade carpet, decorative laminate, galvanized metal 

ductwork, and ceiling tile. Building materials were cut into 

coupons of small, defined size and the TICs and CWAs were 

applied at a rate equivalent to 1 g m-2, which is representative 

of a potential indoor contamination scenario. The coupons to 

which TICs were applied were approximately 5 cm2

 and the 

coupons to which CWAs were applied were approximately 

10 cm2. The sizes were chosen so as to take advantage of 

the available area in the test chambers and to optimize the 

spiking volume of chemical being applied to the coupons. 

All decontamination testing with TICs was carried out 

in standard chemical laboratories at Battelle. Due to 

the stringent controls needed for working with CWAs, 

decontamination tests for CWAs were carried out at one 

of Battelle’s certified chemical surety facilities (Battelle 

Biomedical Research Center [BBRC]) near West Jefferson, 

Ohio. Special test chamber equipment and protocols were 

prepared and utilized for conducting this investigation. For 

fumigant decontamination and its associated controls, tests 

were conducted with coupons inside specially fabricated test 

chambers which allowed for controls on temperature, RH, air 

flow over the coupons, and air exchange rate in the chamber. 

In these tests, the decontamination of each chemical (TIC or 

CWA) was investigated separately; however, the behavior of 

a given chemical was investigated on all building material 

types simultaneously. For decontamination tests using 

liquids, the test coupons and associated controls were 

placed in sealed vials containing the decontamination liquid. 

Table 1-2 (on page 3) presents a summary of the matrix of 

building materials and chemicals, together with the target test 

chamber conditions and fumigant and liquid decontamination 

technologies. The materials and chemicals selected for testing 

were based on the previous persistence study and preliminary 

solution testing of liquid decontamination technologies. 

Only the material/chemical combinations with chemical 

persistence sufficient to determine the decontamination 

effects were included in the matrix. For DMMP, ceiling tile 

was used rather than laminate because the persistence study 

showed less than 1% of the spiked DMMP was recovered 

from laminate after one day. Similarly, decontamination 

of GB was evaluated only on carpet because GB was not 

detected on laminate and ductwork in as little as 15 min after 

spiking. GB and TGD were not evaluated with liquid ClO2

because preliminary solution testing showed no efficacy 

compared to the control solution. Therefore, only VX on 

coupons was investigated with the liquid ClO2; spiked 

coupons were placed in water, acidified with acetic acid to 

reduce hydrolysis, as a control.

The temperature and RH inside the test chambers were 

monitored and recorded. There were five replicate coupons 

of each building material type analyzed at each time point, 

for each TIC or CWA. For TICs testing only, air velocity 

over the coupons was measured. To ensure that air was 

passed uniformly across the TIC coupons, two fans were 

used that produced an air velocity of 400 ft min-1 over the 

coupons. A smaller test chamber was used in the investigation 

of fumigation of CWAs. Uniform gas distribution was not 

anticipated to be a problem, so fans were not used in this 

test chamber. 

Table 1-1. Building Materials Used in Decontamination Investigation

Material Lot, Batch, or Observation Manufacturer/

Supplier Name

Decorative laminate Laminate/Formica/White Matte Finish Solid Surface Design

Industrial grade 

carpet

EcoTek 6; Style #M7978, color #910; 

Carpet Corp of America

Shaw Industries, Inc

Galvanized metal 

ductwork

Industry HVAC standard 24 gauge 

galvanized steel; Adept Products Inc 

Accurate Fabrication

Ceiling tile Armstrong 954, Classic Fine Textured Armstrong
3

1.4 Definitions of Coupon Treatments

The types of test and control coupons used in this 

investigation are described in Table 1-3. Test coupons and 

positive control coupons are spiked with TICs or CWAs. 

Laboratory, handling, and procedural blank coupons are 

not spiked with TICs or CWAs. Test and procedural blank 

coupons are exposed to the decontamination treatment. 

Positive control coupons and laboratory and handling blanks 

are not exposed to the decontamination treatment.

Table 1-4 (on page 4) shows surrogate recovery standard 

(SRS) and internal standard (IS) compounds that were 

utilized in the quantitative chemical analyses (See Section 

2.0). This table summarizes the analysis method for extracts 

of building materials and the sampling and analysis methods 

employed in measuring the chemicals in the air over the 

building materials during decontamination. 

Table 1-2. Target Parameters for Decontamination Testing

Chemical Building

Materials

Temperature 

and RHa

Decontamination 

Agent

Air Flow

Over Coupons

Sampling Points 

in Time

TIC

Malathion Carpet

Laminate

24°C,

80% RH

Fumigant ClO2

at 3000 ppm

400 ft min-1 0, 1, 3, 7 h

DMMP Carpet

Ceiling Tile

24°C,

80% RH

Fumigant ClO2

at 3000 ppm

400 ft min-1 0, 1, 3, 7 h

CWA

GB Carpet 22°C,

80% RH

Fumigant ClO2 

at 3000 ppm

0 ft min-1 0, 1, 4 h

GB Carpet 22°C,

NA

Liquid bleachb

at 5000 ppm ClO0 ft min-1 0, 10, 20, 30 min

TGD Carpet

Laminate

Ductwork

22°C,

80% RH

Fumigant ClO2

at 3000 ppm

0 ft min-1 0, 1, 2 h

TGD Carpet

Laminate

Ductwork

22°C,

NA

Liquid bleach

at 5000 ppm ClO0 ft min-1 0, 10, 20, 30 min

VX Carpet

Laminate

Ductwork

22°C,

80% RH

Fumigant ClO2

at 3000 ppm

0 ft min-1 0, 1, 4 h

VX Carpet

Laminate

Ductwork

22°C,

NA

Liquid bleach

at 5000 ppm ClO0 ft min-1 0, 10, 20, 30 min

VX Carpet

Laminate

Ductwork

22°C,

NA

Liquid ClO2

at 3000 ppm

0 ft min-1 0, 10, 20, 30 min

a) RH is not applicable (NA) to testing in which liquid decontamination technologies is used

b) Commercial bleach diluted 1:10 with water

Table 1-3. Coupon Treatments

Coupon Treatment

Positive control 

coupon

Building material coupon spiked with TIC or CWA that is not exposed to 

the decontamination treatment; analyzed together with test coupons at 

the designated time interval

Test coupon Building material coupon spiked with TIC or CWA and exposed to the 

decontamination treatment for the designated time interval

Laboratory blank Building material coupon that is loaded into an extraction vial before all 

other test activities

Handling blank Building material coupon that is exposed to the fume hood atmosphere 

during sample spiking, and then loaded into an extraction vial 

Procedural blank Building material coupon, with no TIC or CWA spike, that is exposed to 

the decontamination or control treatment for the designated time interval
4

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Table 1-4. Selected TICs and CWAs with Analytical Measurement Parameters

Parameter

TICs CWAs

Malathion DMMP GB TGD VX

SRS Fenchlorphos DEEPa TBPb TBP TBP

IS DBBc DIMPd DIMP DIMP DIMP

Extraction Sonication Sonication Shake/stand Shake/stand Shake/stand

Analysis GC/MSe GC/MS GC/FPDf GC/FPD GC/FPD

Air sample collection Tenax® sorbent ® Tenax sorbent Not collected Not collected Not collected

Air sample analysis Extract & C/MS TD-GC/MSg Not applicable Not applicable Not applicable

a) DEEP - diethyl ethylphosphonate

b) TBP - tributyl phosphate

c) DBB - dibromobiphenyl

d) DIMP - diisopropyl methylphosphonate

e) GC/MS - gas chromatography/mass spectrometry in the multiple ion detection mode

f) GC/FPD - gas chromatography/flame photometric detection

g) TD-GC/MS - thermal desorption GC/MS of analytes from Tenax®
5

2.0

Methods

2.1 ClO2 Fumigant Decontamination 

Technology Used with TICs and CWAs

2.1.1 Sabre Technical Services ClO2 Generator

The Sabre ClO2 generator consisted of a 20.3 cm x 20.3 cm 

base onto which a 15.2 cm x 15.2 cm, 91.4 cm high sparging 

column was mounted. A 19 L container with 15 L of the 

ClO2 decontamination solution was placed at the base of the 

sparging column. The ClO2 decontamination solution (an 

aqueous solution consisting of 3 g L-1 of ClO2 plus 1000 ppm 

of sodium chlorite) was prepared just prior to use in each test. 

Using a peristaltic pump, the ClO2 decontamination solution 

was pumped into the sparging column. Air from the test 

chamber was also pumped into and through this column and 

this air was used to sparge the ClO2

 solution so as to form 

a fine mist; this air stream re-entered the test chamber with 

ClO2 at the desired concentration. Variation in the flow rate of 

liquid and air into the sparging chamber was used to establish 

the desired ClO2 concentration in the test chamber. Liquid 

from the reservoir of ClO2 decontamination solution was 

initially introduced into the sparging column at 60 mL min-1. 

When the desired ClO2 concentration in the test chamber was 

achieved, the liquid introduction into the sparging column 

was decreased to 0 mL min-1 until the concentration dropped; 

at that time the system was restarted at brief intervals to 

maintain the desired concentration. The spent liquid exiting 

the sparging column was collected in a reservoir. The air 

from the chamber was recirculated into and out of the 

sparging column. At the end of the decontamination test the 

ClO2 in the system was destroyed by pumping the exhaust 

air through a scrubber containing a sodium thiosulfate (STS) 

trap. The test chambers are described in greater detail in 

Sections 2.3.1 and 2.4.1.

2.1.2 Measurement in the Test Chamber Atmosphere 

The concentration of ClO2 in the test chamber was monitored 

before beginning a test and periodically during the test 

using a titration method. Use of this method assumes, as has 

previously been demonstrated using the Sabre generation 

method, that ClO2 is the only chlorine species in the gas 

being sampled. For this titration method, air in the chamber 

was sampled using an impinger (at a rate of 1 L min-1 

for 2 min) containing 15 mL of 5% potassium iodide in 

phosphate buffer (pH 7.0). Under these conditions ClO2

oxidizes iodide in the phosphate buffer solution to iodine 

and ClO2 gas is reduced to the chlorite ion (ClO -

2 ) which 

dissolves in solution. The molecular iodine that is produced 

appears yellow-brown in aqueous solution. After sampling 

the chamber atmosphere, the impinger solution is acidified 

and the chlorite is allowed to react further with the iodide 

ion, forming additional iodine and reducing the chlorite to 

chloride. The total resulting iodine is then reduced to iodide 

by titrating with standard 0.1 M (molarity, moles per liter)

STS. The titration endpoint is determined when the color of 

the solution changes from yellow-brown to colorless. The 

volume (mL) of STS needed to achieve the color change 

(brown to colorless) is proportional to the amount of iodine 

generated, which is proportional to the gas-phase ClO2

concentration in the air that passed through the impinger. 

Using the formula below, the concentration of ClO2 (in parts 

per million [ppm] volume in air) is calculated as

(1)

where V is the volume of STS titrant (mL, which is 10-3

L); M is the molarity of STS titrant (g divided by formula 

weight) which for STS is equal to its normality, N); SR is 

the sampling rate through the impinger (L min-1); Time is the 

sampling time (min); 1/5 is the stoichiometric ratio of 1 mole 

(mol) ClO2 reacting with 5 mol STS; 24.45 is the ideal gas 

constant, L mol-1, at 25°C, 1 atm; and 1000 is the conversion 

factor (L m-3). The formula weight of an ion species is equal 

to its concentration in ppm at 10-3 M; therefore the results 

from this equation are equivalent to ppm. The calculation 

of concentration of ClO2 is limited to two significant 

figures (e.g., 3100 ppm). The allowable variation in the 

ClO2 concentration (±10%) encompasses the <2% variation 

introduced by differences in test barometric pressure and 

temperature conditions from ideal gas constant conditions 

(1 atm and 25°C). 

2.2 Liquid Decontamination Technologies 

Used with CWAs

Two aqueous solutions of oxidants were selected for testing. 

One oxidant solution was diluted liquid bleach (sodium 

hypochlorite) and the other was aqueous ClO2

.

2.2.1 Liquid Decontamination Solutions Tested

The diluted bleach was prepared fresh daily using Clorox®

brand bleach that was less than 3 months old (based on 

the code on the bottle). Clorox® bleach, 5%–6% sodium 

hypochlorite, was diluted ten fold with deionized water to 

give a nominal concentration of 5000 ppm ClO- oxidant. 

(The concentration of ClO- in the bleach was not measured.)

The ClO2 was prepared fresh daily at a nominal concentration 

of 3000–3500 ppm. This was prepared by adding 36 mL 

of 6 N hydrochloric acid, 105 mL of Clorox® bleach, 100 mL 

of 25% aqueous sodium chlorite to 3000 mL of deionized 

water. The aqueous ClO2 solution was stored in a dark bottle. 

The pH was checked to ascertain that it was between 4.5 and 

7.5 units. 
6

An STS titration method was used to measure the 

concentration of the ClO2 in the liquid decontamination 

solutions. For this titration method, 5.0 mL of phosphate 

buffer (pH 7.0) and a 5.0 mL sample of the ClO2 solution 

was added to potassium iodide solution (150 mL water into 

which 1.0 g of potassium iodide was dissolved). Under these 

conditions ClO2 oxidizes iodide in the phosphate buffer 

solution to iodine and ClO2 gas is reduced to the chlorite 

ion which dissolves in solution. The molecular iodine that 

is produced appears yellow-brown in aqueous solution. 

The total resulting iodine is then reduced to iodide by 

titrating with standard 0.1 M STS. The titration endpoint 

is determined when the color of the solution changes from 

yellow-brown to colorless and is recorded as “A”. To the 

solution, 5.0 mL of 6 N hydrochloric acid is added and the 

titration is repeated; the result is recorded as “B”. 

The concentrations (mg/L) of ClO2 and chlorite in the 

solution are calculated using Equations 2 and 3. 

 

A = mL of titrant to endpoint before acidification

N = normality of STS titrant (moles = equivalents)

V = mL of sample

67,450 = equivalent weigh (g mole-1) of ClO2 x 1000 mg g-1

 (3)

B = mL of titrant to endpoint after acidification

4A = proportion of chlorite measurement due to ClO2

16,860 = equivalent weight (g mole-1) of chlorite x 

1000 mg g-1

2.2.2 Liquid Decontamination Test System

The liquid decontamination tests were carried out in 40 

mL glass vials. A coupon of specified building material 

was spiked with the indicated CWA and placed into the 

vial which contained 10 mL of decontamination solution. 

The cap was placed securely on each vial, and the vial 

was laid horizontally so that the decontamination solution 

fully covered the test coupon. The liquid decontamination 

investigation is described further in Section 2.4.2. 

2.3 TICs

2.3.1 Test Chamber for Fumigant Decontamination Tests

A customized test chamber consisting of fabricated and 

off-the-shelf equipment and components was assembled and 

used to carry out the investigation of the decontamination 

of TICs. The 448 L test chamber (Labconco) is shown in 

Figure 2-1 (on page 6). The temperature in the chamber was 

maintained between 23°C and 25°C. Hydrocarbon-free zero 

air was supplied to the test chamber by a zero air generator 

(AADCO). To achieve the desired RH in the chamber 

at the start of a test, mass flow controllers (MFC; Sierra 

Instruments) admitted both dry air and humid air in known 

proportions. One MFC admitted moisture-free air to the test 

chamber at a rate of 4.25 L min-1. The second MFC admitted 

3.25 L min-1 of dry air through a 10 L min-1 RH generator 

(Fuel Cell Technologies). The relative amounts of the two 

air streams were adjusted to reach 80% ± 5% RH inside the 

test chamber. A small 8-cm fan (Papst Model 8412), mounted 

in the upper left side of the chamber, ensured that the test 

chamber atmosphere remained well-mixed. 

Temperature and RH were either recorded in real-time every 

minute (for six of eight tests with TICs) with a National 

Institute of Standards and Technology (NIST)-traceable 

thermo-hygrometers (Control Company Model 4185), or 

in near real-time roughly every 15 to 20 min (for two of 

the eight tests) with a hygrometer (Control Company model 

number 15551-126). 

The building material coupons were placed on a customfabricated polycarbonate carousel that was mounted inside 

the test chamber, as shown in Figure 2-1. Two 8-cm fans 

were positioned in a straight line along the carousel diameter 

so as to pass air directly above the coupon surfaces. The 

carousel completed one full rotation each minute. The 

operation of the carousel was controlled to ensure that air 

was passed across all coupons as uniformly as possible for 

the duration of each 7 h test. Each of the two fans produced 

an air velocity of 400 ft min-1 over the coupons as measured 

by anemometers (TSI model 8455) placed downstream of 

each of the two carousel fans. 

To maintain one air exchange h-1 in the test chamber during 

the without decontamination test with malathion, 7.5 L min-1

of hydrocarbon-free air (containing less than approximately 

0.1 ppm total hydrocarbons) was admitted to the chamber. 

For all other tests, no air was admitted to the chamber during 

testing; maintaining essentially static conditions inside 

the test chamber allowed for better stability in the ClO2

concentration. The flow rate of the air sampling performed 

using Tenax® adsorbent cartridges to determine the gasphase TIC concentrations resulted in small air exchange 

rates—only 0.03 to 0.05 air exchanges h-1 during 1 or 3 h 

of sampling. Additional description of the air sampling is 

provided in Section 2.3.7. Because the control tests without 

fumigant ClO2 were conducted at a higher air exchange rate 

(1 air exchange h-1), the control test for the volatile DMMP 

was repeated with the minimal air exchange rate. As there 

was no loss of malathion from the control coupons at the high 

air exchange rate, this control was not repeated at a lower air 

exchange rate.
7

2.3.2 Building Materials

The test coupons included both porous (ceiling tile and 

industrial grade carpet) and non-porous (decorative laminate) 

surfaces. Test coupons were cut to 3.5 cm length x 1.5 cm 

width (5.25 cm2) from larger pieces of stock material. Test 

coupons were each visually inspected prior to being used in 

any test. Coupons with anomalies on the application surface 

were not used.

2.3.3 Sequence of Testing

The test sequence for each TIC and type of building material 

was (1) the control condition (without ClO2 decontamination) 

followed by (2) decontamination at 3000 ppm ClO2. Each 

test included 25 coupons described in Table 2-1. At each 

time point (1, 3, and 7 h), five test coupons, and one each of 

the procedural blank, handling blank, and positive control 

coupon were extracted and analyzed to determine the mass of 

the TIC in the extract. At each time point during the control 

condition tests (1, 3, and 7 h), five positive control coupons, 

and one each of the procedural blank, handling blank, 

and handling positive control coupon were extracted and 

analyzed to determine the mass of the TIC in the extract. The 

laboratory blank coupon was analyzed with the 1 h samples. 

The same regimen was used for the tests done both with and 

without decontamination. The test chamber was thoroughly 

ventilated after a test with ClO2

 before starting a control test 

where there was no ClO2 being admitted to the chamber.

2.3.4 Source of TICs 

The source, lot number and purity of the TICs used for the 

decontamination tests are listed in Table 2-2 (on page 8)

(upper section of table); these parameters are also listed in 

Table 2-2 (lower section) for the secondary source material 

used in the QA performance evaluation (PE) audit.

Figure 2-1. Frontal (left) and Overhead (right) Views of Test Chamber Used for Decontamination Test of TICs

Table 2-1. Types of Coupons Used in the TIC Fumigation Investigation

Coupon (n) Treatment Coupons per Time

Test coupon

(n = 15)

Spiked with TIC and exposed to chamber conditions 

(with or without ClO2)

Five removed from chamber after each of 

1, 3, and 7 h exposure times 

Procedural 

blank (n = 3)

Not spiked with TIC, and exposed to chamber 

conditions (with or without ClO2)

One removed from chamber after each of 

1, 3, and 7 h exposure times

Handling blank

(n = 3)

Not spiked with TIC, exposed in the fume hood during 

the spiking process, then placed into sealed vials

One removed from vial and analyzed 

along with test coupons at each time 

point (1, 3, and 7 h)

Handling 

positive control

(n = 3)

Spiked with TIC and sealed in vials outside 

of test chamber

One removed from vial and analyzed 

along with test coupons at each time 

point (1, 3, and 7 h)

Laboratory blank 

(n = 1)

Not spiked with TIC and sealed in vial outside 

of test chamber

One removed from vial and analyzed at 

1 h time point

n = number of samples
8

Table 2-2. Source of TICs and PE Audit Standards

Chemical Manufacturer/

Supplier Name Lot Number Purity or 

Concentration

Concentration 

as Applied

Materials used for recovery and efficacy tests

Malathion Chem Service, Inc. 343-110B 99.2% 10 mg mL-1

in acetone

DMMP Sigma-Aldrich 10110EA 97% 10 mg mL-1

in acetone

Materials used for QA performance evaluation audit

Malathion Chem Service, Inc. 332-16B 98% 10 mg mL-1

in acetone

DMMP Chem Service, Inc 08113TC 97% 10 mg mL-1

in acetone

2.3.5 Application of TICs to Test Coupons

For both analytical method recovery testing and 

decontamination testing, the test and positive control 

coupons were spiked with 50 μL of 10 mg per mL 

(mg mL-1) of individual TICs to achieve a loading of 500 

μg (~1 g m-2). The addition of 500 μg of a TIC to carpet, 

laminate, or ceiling tile coupon is equivalent to 0.5 mg per 

5.3 cm2, or about 1 mg per 10 cm2 or 1 g m-2. The spike of 

each TIC was delivered from a variable volume pipettor 

(Eppendorf) onto each test coupon in a laboratory fume 

hood separate from the test chamber. 

One laboratory blank coupon per test was not exposed 

to TICs or to the laboratory atmosphere in which the test 

chamber resides. Instead, when the coupons were retrieved 

from storage, these blank coupons were placed immediately 

into an airtight vial for subsequent extraction. Additional 

laboratory blank coupons that were designated as handling 

laboratory blanks for the different sampling intervals were 

exposed to the laboratory air during the spiking of samples. 

These blanks were loaded into vials when other coupons 

were loaded into the chamber. Then, when coupons were 

retrieved from the chamber for analysis, a handling blank 

coupon was also retrieved for analysis. All other coupons 

retrieved from storage were placed in the fume hood where 

the test coupons and positive controls were spiked. The 

process handling blank coupons were not spiked with TICs, 

but were in the hood during the spiking and handling of the 

test coupons. Subsequently, the process blank coupons were 

in the chamber during the decontamination test.

For the analytical method recovery tests, the TIC and 

SRS solutions were spiked onto the coupons just prior to 

extraction. A short drying time was used to allow the solvent 

to evaporate before extraction (Table 2-3). Similarly, for 

decontamination tests, the coupons were placed in the 

laboratory fume hood and spiked with the appropriate TIC 

solution. The solvent was allowed to evaporate before 

the coupons were placed in the test chamber. The solvent 

evaporation times, listed in Table 2-3, were selected on the 

basis of the TIC and coupon type. The test chamber was 

already equilibrated at the appropriate temperature and RH 

when the coupons were added. For the decontamination tests, 

the SRS was not spiked onto each coupon until just before 

analytical extraction.

Table 2-3. Solvent Evaporation Times for TICs Spiked 

on Various Building Materials

TIC Material Evaporation Time (min)

Malathion Carpet 30

Malathion Laminate 3

DMMP Carpet, ceiling tile 1

2.3.6 Extraction Method for TICs from Test Coupons

For extraction, each coupon was placed into a 22 mL amber 

glass vial and then spiked with 25 microliters (μL) of a 

10 μg μL-1 solution of the appropriate SRS (to deliver 250 

μg) for extraction. A 20 mL aliquot of acetone was added 

to each vial; the vial was sealed with a screw-cap lid and 

ultrasonicated for 30 min in an ultrasonic bath (Branson 

5510). The extract was decanted to either a 200 mL TurboVap 

tube or a 25 mL Kuderna-Danish (KD) tube with attached 

125 mL reservoir. Carpet samples were extracted with three 

replicate aliquots of acetone; extracts were combined before 

concentration. Laminate and ceiling tile coupons required 

only one extraction cycle. The number of extraction cycles 

and concentration technique used for each TIC and building 

material combination are listed in Table 2-4. Extracts were 

concentrated to a final volume of 5 mL and spiked with 25 μL 

of a 10 μg μL-1 solution of the appropriate IS to give a 50 μg 

Table 2-4. Extraction and Concentration Techniques Used for TICs

Coupon Type TIC Extraction 

Technique Extraction Concentration 

Technique

Carpet Malathion Sonication 3 x 20 mL TurboVap

Carpet DMMP Sonication 3 x 20 mL KD

Laminate Malathion Sonication 1 x 20 mL TurboVap

Ceiling tile DMMP Sonication 1 x 20 mL KD
9

mL-1 concentration. A 1 mL aliquot was then filtered through 

a disposable syringe filter (GD/X; Whatman) prior to the gas 

chromatography/mass spectrometry (GC/MS) analysis. 

2.3.7 Air Sampling and Analysis of TICs Using Tenax®

Sorbent Air Sampling Tubes

Sampling of the chamber air to assess vapor phase 

concentrations of the TICs was accomplished using active 

sampling onto the Tenax® TATM sorbent. The air sampling 

cartridges consisted of stainless steel thermal desorption 

tubes (0.25 inch outside diameter x 3.5 inch length) packed 

with 200 mg of 60/80 mesh Tenax® TA polymer (Markes 

International, Ltd). Sampling was performed using calibrated 

mass flow controllers. For malathion, sampling rates were 

500 mL min-1 for control conditions and 200 mL min-1 for test 

conditions, both for 3 h. The sampling rates were lowered 

to reduce the air exchange rate in order to stabilize the ClO2

concentration during decontamination testing. For DMMP, all 

sampling was performed at 100 mL min-1 for 1 h. The longer 

sampling times and higher sampling rates for malathion were 

used because it was expected that chamber air concentrations 

of malathion would be considerably lower than those of 

DMMP due to vapor pressure differences.

At the conclusion of sampling during malathion tests, the 

Tenax® air cartridges were spiked with 100 μg of the SRS 

(fenchlorphos) and extracted with 2 mL of acetone; after 

addition of the IS, the 2 mL volume was analyzed without 

further concentration. The GC/MS analysis for the air 

extracts was performed as described in Section 2.3.8 for 

coupon extracts.

At the conclusion of sampling during DMMP tests, 

the Tenax® air cartridges were spiked with diisopropyl 

methylphosphonate (DIMP) as an IS and analyzed using 

thermal desorption (TD) GC/MS technique (using a Markes 

Unity Thermal Desorption unit interfaced to an Agilent 

6890/5973 GC/MS). Before desorption, a tube leak check 

was performed to ensure quantitative sample transfer. After 

the leak check, the tube was flushed with helium for one 

min at 40 mL min-1, with the effluent sent to vent. Following 

the purge, analytes were desorbed from the sorbent tube at 

20 mL min-1 for 10 min at 300°C; analytes were collected 

on the focusing trap (Markes General Purpose Graphitized 

Carbon trap) which was held at 25°C. The analytes were then 

desorbed from the focusing trap at 300°C for five min using 

the maximum heating rate (>60°C sec-1) and a flow rate of 

40 mL min-1. A portion of this flow was directed to the GC/

MS. Minor modification of the tube desorption flow rate was 

used in various sets of analyses to optimize the percentage 

of analyte transfer from sorbent tube to GC/MS for analysis. 

In each set, however, samples and standards were analyzed 

under identical conditions. The GC/MS conditions for 

analysis of vapor phase DMMP are given in Table 2-5.

2.3.8 Analysis Method for TICs

Coupon extracts were analyzed using GC/MS in multiple 

ion monitoring mode on an Agilent 6890/5973 GC/MS. Data 

collection, reduction, and analysis were performed using 

Agilent Chemstation software, version B.02.05. The GC and 

MS conditions used for analyses of the two different TICs are 

listed in Table 2-6. 

Table 2-5. GC and MS Conditions for Analysis of DMMP in Air Samples

Parameter Condition

GC column DB-5ms; 60 meters (m) x 0.32 mm inside diameter x 

0.25 μm film thickness (Agilent)

Temperature program 50°C (2 min); 50°C–140°C @ 6°C min-1; 140°C–250°C 

@ 20°C min-1; hold 0.5 min (23 min run time)

Transfer line temperature 280°C

MS source temperature 230°C

Quadruple temperature 150°C

Flow rate 1.5 mL min-1 at 50°C

Ions monitored m/z 94, 79 for DMMP and m/z 97, 123 for DIMP

Table 2-6. GC and MS Conditions for TIC Analyses

Parameter Condition

GC columna DB-1701; 30 m x 0.25 mm ID x 0.15 μm film thickness; J&W Scientific

Inlet liner Siltek double gooseneck

Temperature program 

for malathion

100°C (2 min); 100°C–180°C @ 10°C min-1; 180°C–220°C @ 5°C min-1; 

220°C–260 °C @ 20°C min-1 (20 min run time)

Temperature program 

for DMMP

50°C (2 min); 50°C–95°C @ 3°C min-1; 95°C–250°C @ 20°C min-1; 

hold 2.25 min (27 min run time)

GC injection 1 μL splitless at 280°C

Transfer line temperature 280°C

MS source temperature 230°C

Quadruple temperature 150°C

a) In all cases helium was the carrier gas: 0.8 mL min-1 flow for malathion; 1 mL min-1 for DMMP
10

Table 2-7. GC Retention Times and Monitored Ions 

for TIC Analyses

Chemical GC Retention 

Time, min

Ions Monitored, m/z

Quantification Ion Qualifier Ion

Malathion 17.2 173 127

SRS 15.5 285 125

IS 16.5 312 152

DMMP 9.0 94 79

SRS 17.0 111 93

IS 15.6 97 123

Two ions were monitored for each TIC, SRS, and IS. The primary ion was used for quantification 

and the secondary ion was used for qualitative confirmation of identification. Criteria for 

identification of an analyte included the correct GC retention time ±0.02 min, chromatographically 

co-maximized primary and secondary ions and correct ratio between the relative intensities of the 

primary and secondary ions. The monitored ions and GC retention times are listed in Table 2-7.

The quantification was performed using the IS method.[2] The IS was present at the same 

concentration in all samples and standards. The 11-point calibration curve spanned the range of 

0.1–150 μg mL-1. This concentration range is equivalent to 0.1% to 150% recovery of the mass 

applied to coupons. 

The full calibration curve was analyzed at the start of each analysis set. Samples were then analyzed 

with the 20 μg mL-1 standard run after every five samples as a continuing check on the calibration. 

If the calculated concentration of the continuing calibration standard showed a variance more than 

20% beyond its true concentration, the cause of the problem was investigated and the five samples 

before and after this standard were reanalyzed. Calibration curves were constructed using a quadratic 

least-squares regression analysis routine with the weighting scaled by the inverse of the analyte 

concentration. Typically, the calibration data could be fitted to a single curve for malathion and 

DMMP. However, due to the wide calibration range, occasionally two separate calibration curves 

(one with high values and one with low values) were needed to define the malathion calibration data. 

2.3.9 Calculation of TIC Recovery Efficiency, Percent Recovery, 

and Decontamination Efficacy

The analytical method performance recovery efficiency for both a TIC and its matched SRS extracted 

from a spiked coupon was determined according to the following formula:

(4)

Using results from Equation 4 for SRS and TIC recoveries, the analytical method recovery ratio 

between the mean analytical method SRS recovery and the mean analytic method TIC recovery was 

determined using the following equation:

(5)

The raw recovery value for the individual TIC or SRS from a building material coupon during a 

test was calculated by multiplying the mass (μg mL-1) determined in the analytical method by the 

extract volume (mL). The raw recovery values were adjusted using the SRS/TIC recovery ratio from 

Equation 5 to generate the normalized TIC recovery values according to the following equation:

(6)
11

The mean normalized TIC recovery from Equation 6, at each sampling interval, was divided by the 

mean normalized TIC recovery at Time 0 of the test to obtain the percent recovery at a given time 

reported in the results: 

(7)

The decontamination efficacy of a decontamination technology was calculated as the ratio of 

the mean recoveries extracted from a coupon at a given time (from Equation 7) for the test 

(decontaminated) and control using the following equation:

(8)

The SRS recovery in each particular sample was used to correct for potential differences in 

application of the analytical method to each individual sample. The SRS/TIC recovery ratio, 

calculated using Equation 5, used data from the recovery measurements of these compounds in the 

method performance tests. This ratio was used to make an adjustment for the fact that an isotopicallylabeled chemical equivalent (e.g., deuterium - or C13-labeled) of each TIC was not available for 

use as the SRS. In many analytical methods, a labeled version of an analyte is used as the SRS; in 

that case the analyte and SRS are assumed to be recovered through an analytical method to the same 

extent. Where an isotopically-labeled version of an analyte is not available, an SRS is chosen to be as 

similar as possible to a given analyte so as to minimize the potential for differential loss mechanisms. 

However, there may be differences in recovery between an analyte and SRS, and this difference 

requires a minor adjustment based on differential recoveries.

To convert a Tenax® sorbent sample extract concentration for malathion to an air concentration of 

malathion in the test chamber, the following equation was used:

(9)

To convert an amount of DMMP measured on a Tenax® sorbent tube to a DMMP air concentration in 

the test chamber, the following equation was used:

(10)

2.4 CWAs 

2.4.1 Test Chamber for Fumigant Decontamination Tests

Two test chambers were constructed for testing of each CWA. One chamber housed the control 

coupons that were not exposed to ClO2; the second chamber was interfaced to the Sabre ClO2

generator, so that the coupons housed in this chamber could be decontaminated. Each chamber 

consisted of a specially fabricated polycarbonate (Lexan®) housing with removable custom built 

shelves made of 26 gauge cold rolled steel. The chamber had dimensions of 26 cm x 29 cm x 27 

cm, or 20.4 L. A new polycarbonate chamber with shelves was used for each CWA tested. The 

temperature in the chambers was that of the ambient air in the laboratory. An ultrasonic fog generator 

was used to establish ~100% RH air in a separate fogging chamber. The humidified air from the 

fogging chamber was pumped through a water trap and then into the two test chambers until the 

test chambers reached 80% RH. Each chamber was then sealed for the test. The test chamber 

was interfaced with the Sabre ClO2 generator, which was described earlier (Section 2.1.1). At the 

conclusion of each test, the chambers were decontaminated and decommissioned according to 

Department of the Army regulations and BBRC standard operating procedures.

The temperature and humidity in the chamber were monitored continuously (at 30 min intervals) 

by the heating, ventilation, and air conditioning (HVAC) system. The HVAC readings were verified 

twice daily using a calibrated NIST-traceable thermometer/hygrometer with accuracy of ±1°C 

for temperature and ±5% for RH. All of the readings taken in the laboratory indicated that the 

temperature and RH were constant throughout the test periods.
12

2.4.2 Test Chamber for Liquid Decontamination Tests

As described earlier (Section 2.2.2), the testing for 

decontamination of building material coupons with liquid 

solutions was carried out in individual 40 mL vials. Each 

spiked or blank coupon was placed in a vial and 10 mL of 

decontamination solution was added. The vial was capped 

securely laid horizontally so that the coupon was bathed 

completely in the decontamination solution during the test 

period. The vials were periodically shaken for the first few 

hours to extract the CWA from the coupon and the coupons 

were allowed to stand in the extraction solution overnight. At 

the completion of the specified decontamination period, the 

coupon was removed and shaken lightly to remove as much 

aqueous liquid as possible; the SRS was added to the coupon 

immediately and placed into a 40 mL vial containing 10 mL 

of extraction solvent. The vials were again shaken a few 

times before the coupon was removed.

Neutralization of the decontamination solution was not used 

in the decontamination efficacy tests because the preliminary 

solution tests (Section 2.2.2) suggested that loss of CWA 

recovery occurred in neutralized solution, except possibly 

for GD. Rapid extraction was preferred to inclusion of a 

neutralization step. Therefore, the coupons were removed 

from the decontamination solution, shaken lightly to remove 

excess liquid, spiked with the SRS, and placed directly into 

the extraction solution.

2.4.3 Building Materials

The building materials that were utilized in testing for 

decontamination efficiency for fumigant and liquid 

decontamination technologies are listed in Table 2-8; these 

materials included porous, adsorptive and non-porous surface 

types. Test coupons were cut to the sizes indicated in Table 

2-8 from larger pieces of stock material.

Table 2-8. Building Material Test Coupon 

Characteristics for CWA Decontamination Tests

Material Approximate Coupon Surface,

Length x Width, cm

Material 

Preparation

Laminate 6.5 x 1.5 (9.75 cm2) Clean with 

acetone

Carpet 6.5 x 1.5 (9.75 cm2) None

Ductwork 6.5 x 1.5 (9.75 cm2) None

2.4.4 Sequence of Testing

For the fumigant testing with ClO2

 generated by the Sabre 

system, all building material types were tested concurrently 

in a given test. However, since the test (i.e., fumigant) and 

control chambers were both sealed to maintain the RH, only 

enough coupons were loaded into the identical chambers for 

a single time increment of decontamination. For example, 

when testing decontamination of VX, the identical chambers 

were each loaded with five spiked carpet coupons, five 

spiked laminate coupons, five spiked ductwork coupons, and 

one procedural blank of each material type. The chambers 

were sealed and the decontamination and control tests were 

then carried out for 1 h. After unloading the chambers and 

ventilating them, an identical set of coupons were prepared, 

loaded into the chambers, and this time the test was 

conducted for 2 or 4 h, depending on CWA. 

To select appropriate conditions for the liquid 

decontamination tests, several preliminary tests were 

conducted to determine whether neutralization of the liquid 

decontamination agent was needed prior to extraction of 

the CWA with the organic solvent. To carry out this test, 

each CWA was spiked into both the full strength liquid 

decontamination (bleach or ClO2

) and the neutralized liquid 

decontamination solution. The CWA was held in the 10 mL 

decontamination solution for 1 h prior to addition of the 

SRS and the 10 mL of hexane for extraction; in contrast, the 

CWA was held for 15 sec in the neutralized decontamination 

solution prior to addition of the SRS and the 10 mL of hexane 

for extraction. The neutralized solution consisted of the 

decontamination liquid and STS equivalent to 10% more 

than that required to neutralize the oxidant; this solution was 

then adjusted to pH 7.0 by the addition of acetic acid before 

extraction with hexane. 

For the tests of decontamination with liquid bleach, testing 

was done sequentially with individual combinations of 

CWA and building material because of the very short 

decontamination times being tested (10–30 min). The 

sequence of testing included first, the analysis of Time 0 

positive controls without decontamination and laboratory 

blanks of a given building material and CWA for verification 

of mass applied. This group of samples included five positive 

control coupons of the building material spiked with 1 mg 

of the CWA, and one coupon of that material that was a 

laboratory blank. These coupons were spiked (as needed) 

and immediately extracted in hexane. Then, that same 

combination of building material and CWA was tested for 

different durations with and without decontamination. Each 

test grouping included, for instance, five carpet coupons 

spiked with 1 mg of CWA and loaded into vials containing 

10 mL of diluted bleach (i.e., with decontamination), five 

carpet coupons spiked with 1 mg of CWA and placed 

in empty vials (i.e., without decontamination), and one 

procedural blank carpet coupon that was placed in a vial 

with diluted bleach. This sequence was completed for all 

decontamination test durations with carpet, then laminate and 

then ductwork first for VX, then repeated again with TGD, 

and then repeated a third time with GB (here, tested only on 

carpet coupons because GB was not persistent on laminate or 

ductwork). The only deviation to the test/QA plan was that 

positive control coupons (i.e., without decontamination) for 

VX were not prepared for the 10 and 20 min decontamination 

durations; these coupons were only prepared for the 30 min 

test duration due to the very low vapor pressure and expected 

stability of VX over 10 and 20 min test periods. 

In each test combination of CWA and building material, the 

ten spiked building material coupons were loaded into vials, 

alternating between a vial containing the decontamination 

solution and a control vial that was empty, as a control for 

bleach, or containing acidified water, as a control for ClO2 

decontamination solution. This alteration between test and 
13

control vials was done to minimize the effect of loading 

time. The same alternating sequence was used in retrieving 

coupons from vials, spiking them with SRS and loading them 

into the hexane-containing extraction vials — once again 

to minimize the effect of time required for spiking SRS and 

loading the coupon into an extraction vial. This was deemed 

potentially important for the more volatile CWAs (GB 

and TGD).

Decontamination tests using ClO2 decontamination solution 

were conducted only for VX because the results of the 

solution tests suggested that decontamination of GB and GD 

with ClO2 solution was not effective. Solution testing results 

with VX were inconclusive, possibly due to hydrolysis in the 

aqueous solution. For decontamination with ClO2 solution, 

the same sequence as described above for bleach was used. 

This included preparing only one coupon type at a time, and 

preparing these for only one decontamination duration. 

For decontamination of VX with ClO2 solution, the positive 

control samples (spiked without decontamination) were 

handled differently. VX is quite unstable in alkaline solutions 

and this was a possible explanation for the inability to 

recover VX from neutralized ClO2 decontamination solution 

in the solution tests. Therefore, rather than load the positive 

control coupons into empty vials for the test duration, they 

were loaded into vials containing 10 mL of acidified (pH 

4.5–<7) water; VX is quite unstable in alkaline solutions. The 

recovery of VX from acidified water enables the hydrolysis 

effects of water to be differentiated from the decontamination 

effects of the ClO2.

2.4.5 CWAs and Surrogate Recovery Standard

The source, lot number, and purity of the CWAs used in this 

investigation are listed in Table 2-9. 

Polymethyl methacrylate was added, 5% on a weight:volume 

basis, as a thickening agent for GD. Typically, 5 mL of TGD 

was prepared in a batch.

2.4.6 Application of CWAs to Test Coupons

For both the control tests (with no ClO2

 admitted to the 

chamber) and the decontamination tests with ClO2, the 

coupons were spiked with the individual CWA to achieve 

a loading of approximately 1 g m-2. All building materials 

were spiked with 1 μL of neat CWA to deliver a mass of 

approximately 1 mg to one 10 cm2 surface of each coupon. 

A 50 μL repeating dispenser pipette (Hamilton) that delivers 

50 equal volumes per syringe load was used to apply the 

CWA to the test coupons. Concurrently with spiking the test 

coupons, 1 μL of each CWA was spiked directly into 10 mL 

of the extraction solvent and this solution was analyzed to 

measure the mass of CWA applied to the building materials 

(i.e., a confirmation spike). The mass of CWA applied to test 

coupons, as determined from analyses of the confirmation 

spikes, are listed in Table 2-10. 

For these decontamination tests, the coupon spiking was 

completed within approximately 30 sec, and coupons were 

loaded directly into the test chambers after spiking. Drying 

time was not needed since there was no solvent involved.

Table 2-9. Source of CWAs and SRS

Chemical Manufacturer/Supplier Purity or 

Concentration

Concentration 

as Applied

Materials used in this investigation

GB U.S. Army 96 Neat

GD U.S. Army 94 95% neat

VX U.S. Army 70 Neat

TBP (SRS) Sigma-Aldrich 99 Neat

Standard Analytical Reference Material used to confirm CWA purity

GB Institute of Chemical Defense 1 mg mL-1 NA

GD Institute of Chemical Defense 1 mg mL-1 NA

VX Institute of Chemical Defense 1 mg mL-1 NA

Table 2-10. Mass of CWA Applied to Building Material Coupons

Chemical Mass of CWA Applied for Decontamination Tests

Fumigant ClO2 Liquid Bleach Liquid ClO2

GB 916 μg 830 μg NTa

TGD 880 μg 1530 or 1570 μg, 

depending on day NT

VX 833 μg 840 μg 950 μg 

a) NT = not tested
14

2.4.7 Extraction Method for CWAs

For extraction of building material coupons, 1 μL of the SRS 

(1 μL = 1 mg) was first applied as neat material to the coupon 

just prior to extraction. The coupon was then loaded into a 

40 mL sample extraction vial and a 10 mL aliquot of hexane 

containing the IS at 100 μg mL-1 was added. The vial was 

shaken briefly and then the building material was allowed 

to stand in the solvent overnight (~14–16 h) for passive 

extraction. The vials were shaken again before removal of the 

analysis aliquot.

2.4.8 Analysis Method for CWAs

Sample extracts were analyzed using gas chromatography 

with flame photometric detection (GC/FPD) on an Agilent 

6890 GC. Data collection, reduction, and analysis were 

performed using Agilent Chemstation software, Version 

B.02.05. The GC conditions used for analyses of the three 

different CWAs are listed in Table 2-11. 

The GC retention times were monitored for each CWA, SRS, 

and IS. Identification of an analyte entailed matching the 

correct GC retention time ±0.02 min. The GC retention times 

are listed in Table 2-12. The quantification was performed 

using the IS method.[2] The 9-point calibration curve 

spanned the range of 0.24–190 μg mL-1. This concentration 

range is equivalent to 0.24% to 190% recovery of the mass 

applied in this investigation. The IS was present at the same 

concentration in all samples and standards. 

2.4.9 Calculation of CWA Recovery Efficiency, Percent 

Recovery, and Decontamination Efficacy

The calculations of recovery efficiency (Equation 4), 

percent recovery (Equation 7), and decontamination 

efficacy (Equation 8) were carried out using the same 

equations listed and described in Section 2.3.9 for the TICs. 

The only exception here for the CWAs was that SRS and 

relative extraction efficiency corrections were not made in 

calculations for the data from the liquid decontamination 

tests. In these data, for unknown reasons, the SRS recoveries 

from the coupons were not stable. The SRS recoveries were 

measured, but were not useful for comparison.

2.5 Qualitative Evaluation of the Impact of ClO2

Fumigation on Building Materials

A total of eight laboratory blanks (building materials not 

exposed to ClO2) and 24 procedural blanks (building 

materials exposed to ClO2) were maintained under controlled 

ambient temperature and RH conditions for assessment of 

long-term changes in appearance or structure due to ClO2 

fumigation. For this work, two polycarbonate chambers, 

one 30 L and the other 15 L, were fabricated, and connected 

via a cylindrical flow-through unit. The front end of the 

larger chamber was connected to the humidification system 

described earlier; the back end of the smaller chamber was 

exhausted to ambient. Ambient air, typically at 24°C and 

40% RH, was directed through these chambers with a flow 

of one air exchange h-1. The laboratory blank coupons were 

placed in the first chamber and the procedural blank coupons 

exposed to ClO2 were placed in the second chamber. 

Table 2-11. GC/FPD Conditions for CWA Analyses

Parameter Condition

GC column for GBa DB-5; 25 m x 0.32 mm inside diameter x 0.52 μm 

film thickness; Agilent

Temperature program for GB 55°C (1 min); 55°C–100°C @ 10°C/min; 100°C 

–250°C @ 25°C/min (11.5 min run time)

GC column for TGDa Rtx-5; 30 m x 0.32 mm inside diameter x 0.50 μm 

film thickness; Restek

Temperature program for TGD 40°C (1 min); 40°C–100°C @ 10°C/min; 100°C 

–250°C @ 30°C/min (12 min run time)

GC column for VXa DB-5; 25 M x 0.32 mm ID x 0.52 μm film 

thickness; Agilent

Temperature program for VX 55°C (1 min); 55°C–100°C @ 10°C/min; 100°C 

–300°C @ 25°C/min (13.5 min run time)

GC injection 1 μL splitless at 250°C

Detector temperature 250°C

Hydrogen flow 70 mL min-1

Oxidizer flow Air at 90 mL min-1

Makeup gas flow Nitrogen at 15 mL min-1

a) In all cases helium was the carrier gas with a flow rate of 1.7 mL min-1

Table 2-12. GC Retention 

Times for CWA Analyses

Chemical GC Retention 

Time (min)

GB 3.49

SRS 11.6

IS 6.92

TGD isomer 1 6.62

TGD isomer 2 6.67

SRS 11.8

IS 6.92

VX 6.16

SRS 5.74

IS 2.05
15

3.0

Quality Assurance/Quality Control

QA/quality control (QC) procedures were performed in 

accordance with the TTEP Quality Management Plan 

(QMP)[3], the test/QA plan[4], Amendment 2 for ClO2

decontamination of TICs (March 16, 2006), Amendment 6 

for ClO2 decontamination of CWAs (March 21, 2007), and 

Amendment 8 for liquid technologies for decontamination 

of CWAs (July 6, 2007). QA/QC procedures are summarized 

below.

3.1 PE Audit

A PE audit was conducted to assess the quality of the GC/

MS results obtained during these tests. For the two TICs, this 

PE audit was performed by diluting and analyzing standards 

obtained from a secondary source. The secondary source 

standards were diluted to 100 μg mL-1 and analyzed using 

a calibration curve constructed from the primary source 

standards. The results of this analysis are given in Table 3-1. 

The target tolerance was a difference less than 25%; results 

were well within the target tolerance.

A PE audit was conducted to assess the quality of the 

CWA results obtained during these tests. For the three 

CWAs, this PE audit was performed by comparing purity 

of stock solution results against a second source (Standard 

Analytical Reference Material). In addition, PE audits 

were performed for the chamber conditions that affected 

results (time, temperature, RH and flow). The results of 

these analyses are given in Table 3-2, except for time. 

Time comparisons were made four times over the span of 

40 min on April 27, 2007 and May 31, 2007. Time was 

compared to the U.S. government’s time provided by both 

NIST/U.S. Naval Observatory (Military counterpart to NIST) 

and the Department of Commerce (www.time.gov). Each 

measurement was exact to the second, resulting in a percent 

difference of 0.0% for both days. The target tolerance was a 

difference less than 10%; results were well within the target 

tolerance.

3.2 Technical Systems Audit 

The Battelle QA Manager and his designee conducted a 

technical systems audit (TSA) to ensure that the tests were 

being performed in accordance with the QMP, test/QA plan, 

Amendment 2 for ClO2 decontamination of TICs (March 16, 

2006), Amendment 6 for ClO2 decontamination of CWAs 

(March 21, 2007), and Amendment 8 for liquid technologies 

for decontamination of CWAs (July 6, 2007). As part of the 

audit, the Battelle QA Manager and his designee reviewed 

the reference sampling and analysis methods used, compared 

actual test procedures with those specified in the test/QA 

plan, and reviewed data acquisition and handling procedures. 

No significant findings were noted in this audit that might 

impact the quality of the investigation results. The records 

concerning the TSA are permanently stored with the Battelle 

QA Manager. 

Table 3-1. TIC PE Audit Results

TIC Date of Audit Standard 

Concentration

Measured 

Result % Difference

Malathion 10/27/2006 0.100 mg mL-1 0.087 mg mL-1 -13

DMMP 10/27/2006 0.100 mg mL-1 0.104 mg mL-1 4.0

Table 3-2. CWA PE Audit Results

CWA or Parameter Date of Audit Standard Measured Result % Difference

GB 6/06/2007 0.110 mg mL-1 0.114 mg mL-1

0.106 mg mL-1

-3.6

3.6

TGD 5/03/2007 0.110 mg mL-1 0.103 mg mL-1 6.4

TGD 5/11/2007 0.110 mg mL-1 0.109 mg mL-1 c

0.111 mg mL-1 c

0.9

-0.9

VX 5/02/2007 0.070 mg mL-1 0.073 mg mL-1 -4.3

MFCa 5/16–18/2007 1.00 L min-1 1.01 L min-1 b -0.6

Temperature 4/27/2007 19.3°Cc 18.8°Cc 2.6

RH 4/27/2007 36.3%c 37.8%c -4.1

Temperature 5/31/2007 22.1°Cc 22.4°Cc -1.4

RH 5/31/2007 38.8%c 41%c -5.8

a) Mass Flow Controller

b) Average of six results, three for 5/16/2007 and three for 5/18/2007

c) Average of four results
16

3.3 Data Quality Audit

At least 10% of the data acquired during the investigation 

was audited. Battelle’s QA Manager traced the data from 

the initial acquisition through reduction to final reporting, to 

ensure the integrity of the reported results. All calculations 

performed on the data undergoing the audit were checked. 

3.4 QA/QC Reporting 

Each assessment and audit was documented in accordance 

with the test/QA plan and QMP. For this investigation, no 

significant findings were noted in any assessment or audit, 

and no follow-up correction action was necessary. Copies of 

the TSA and assessment reports were distributed to the EPA 

QA Manager and Battelle staff. 

QA/QC procedures were performed in accordance with the 

Program QMP and the test/QA plan for this investigation. 

3.5 Deviations from Test/QA Plan

The test/QA plan envisioned use of a 317 L test chamber for 

testing decontamination of TICs. When the coupon carousel 

and equipment would not fit into this sized chamber, a 448 

L chamber was substituted. This change did not impact the 

investigation.
17

4.0

Results

4.1 Results for Fumigant ClO2 Decontamination

of TICs

4.1.1 Analytical Method Development Results

The analytical methods were tested initially to verify the 

extraction efficiencies of the TICs and their matched SRSs 

from the building materials that were to be used in the 

decontamination tests. These recoveries are listed in 

Table 4-1. 

The mean of the extraction efficiencies for the TICs and 

SRSs were in a range of 73% to 97%. This range of recovery 

was within the acceptance range specified in Appendix A3 of 

the test/QA plan (40% to 120%) and all values were within 

the acceptance level of 3 SD of the mean. The SRS/TIC 

values (0.91–1.11) show that the SRS recovery correlated 

well with the respective TIC recovery. These results show 

that the method development resulted in extraction and 

analysis methods for the TICs that were sufficient to achieve 

the data quality objectives of the test/QA plan (inclusive of 

the requirements in Appendix A3). 

The approximate method detection limits (MDLs) for the 

TICs are listed in Table 4-2. Each MDL was estimated based 

on the signal of the lowest level calibration standard, the 

signal to noise ratio for this concentration and the peak area 

that can be integrated reliably for any signal.

4.1.2 Environmental Conditions during 

Decontamination Tests

The temperature, RH, ClO2

 concentration, and air velocity 

over the coupons during testing were measured as specified 

in the test/QA plan.[4] The averages for temperature, RH, 

ClO2 concentration, and air velocity over the coupons during 

testing, in control and test chambers, are shown in Table 4-3 

(on page 18). Temperature and RH were controlled to 24°C

± 2°C and 80% ± 10% RH. The target ClO2 concentration 

was 3000 ppm. Differences in air velocities among the tests 

were observed. The mean of the average velocities for all of 

the tests was 117 ft min-1; all mean velocities were within 2 

SD of the mean of the averages. The differences in velocity 

within and among tests may be due to small changes in the 

operation of the fans or positioning of the anemometers.

Originally, one air exchange h-1 was planned for the 

persistence testing and the ClO2 fumigation testing. However, 

at one exchange h-1, control of the ClO2 concentrations was 

problematic. Therefore the air exchange rate was reduced to 

<0.1 air exchange h-1 for the ClO2 fumigation testing. 

Due to the high volatility of DMMP, there was a concern 

that the difference in air exchange between the control tests 

(one air exchange h-1) and the decontamination tests (0.1 air 

exchange h-1) would present a variable that would interfere 

with the analysis of data and trends. For this reason, the tests 

Table 4-1. Extraction Efficiencies of TICs and Matched SRSs 

from Building Materials

Material Recovery from Building Material, % ± SDa SRS/TIC 

Recovery Ratiob

TIC SRS

Malathion Fenchlorphos

Carpet 80 ± 3 73 ± 5 0.90

Laminate 80 ± 19 89 ± 4 1.1

DMMP DIMP

Carpet 87 ± 3 87 ± 7 0.99

Ceiling tile 93 ± 3 97 ± 3 1.1

a) Calculated using Equation (Eq) (4)

b) Calculated using Eq (5); carried out using 3 significant figures on TIC and SRS 

recoveries

Table 4-2. MDLs for TICs

Matrix MDL 

Malathion DMMP

In solution 0.01 μg mL-1 0.01 μg mL-1

On coupon 0.05 μg 0.05 μg

In air 0.26 μg m-3 0.70 μg m-3
18

for DMMP (without ClO2 decontamination) were conducted 

a second time at the low air exchange rate to determine 

whether air exchange has any significant effect on recovery. 

The recovery of DMMP on carpet and ceiling tile with 

the two different air exchange rates, shown in Table 4-4, 

demonstrates that there is a small difference after 1 h, but 

that difference largely dissipates by the conclusion of the 7 h 

test. Statistical analysis of these data showed that the small 

differences on the ceiling tile were statistically significant. 

For DMMP, the recoveries at the low air exchange rate were 

used as the basis for comparison with the recoveries after 

decontamination.

There was not a significant loss of malathion from the test 

coupons over a 7 h at one air exchange h-1. Therefore, the 

persistence testing was not repeated at the lower air exchange 

rate. For malathion, the recoveries at one air exchange h-1

were used as the basis for comparison with the recoveries 

after decontamination.

4.1.3 Recovery over Time of TICs on Building Materials 

With and Without Sabre ClO2 Fumigant Decontamination

Individual tests, both with and without the Sabre ClO2

fumigant decontamination technology, were conducted for 

each building material to assess the recovery of the given 

TIC on that building material. As noted in Section 1.3 

(Experimental Design), the decontamination testing covered 

a 7 h time span, and five building material coupons were 

removed from the chamber for testing after 1, 3, and 7 h. In 

addition, analyses of five spiked building material coupons 

that were extracted immediately after spiking (Time 0) were 

used to ascertain the baseline recovery values. The recoveries 

of the spiked TICs from the coupons at Time 0 (0 h) and 

at subsequent times (1, 3, and 7 h) with and without the 

application of the Sabre ClO2 decontamination process are 

listed in Table 4-5 (on page 19).

Table 4-3. Mean Temperature, RH, ClO2 Concentration, and Air Velocity during TIC Decontamination Tests

TIC Material Chamber Mean During the Test

Temp, °C ± SD RH, % ± SD ClO2, ppm ± SD (n) Air Velocity, ft min-1 ± SD

DMMP

Carpet

Control 24.3 ± 0.1 80 ± 4 0 102 ± 11

Test 23.9 ± 0.1 78 ± 3 3300 ± 600

(n = 17) 108 ± 0

Ceiling tile

Control 24.2 ± 0.2 82 ± 3 0 136 ± 18

Test 25.1 ± 0.8 83 ± 2 3010 ± 120

(n = 21) 121 ± 3

Malathion

Carpet

Control 23.7 ± 0.1 84 ± 1 0 108 ± 16

Test 24.4 ± .03 77 ± 2 3050 ± 200

(n = 21) 140 ± 30

Laminate

Control 22.9 ± 0.2 87 ± 2 0 116 ± 11

Test 23.0 ± 1.1 79 ± 3 3010 ± 180

(n = 21) 105 ± 13

Table 4-4. Comparison of Mean Percent Recovery of DMMP with Different 

Chamber Air Exchange Rates

TIC Material Time (n) Mean Recovery, % ± SD

0.1 Air Exchange h-1 1 Air Exchange h-1

DMMP

Carpet

1 h (n = 5) 33 ± 2 40 ± 5

3 h (n = 5) 24 ± 3 26 ± 3

7 h (n = 5) 16 ± 3 18 ± 2

Ceiling tile

1 h (n = 5) 39 ± 4 32 ± 1

3 h (n = 5) 28 ± 1 19 ± 2

7 h (n = 5) 12 ± 1 9.4 ± 0.4
19

As shown in Table 4-5, the amount of DMMP on carpet 

and ceiling tile decreased quite substantially both with 

and without the decontamination treatment. At this point, 

it is not clear whether the significant decrease over time 

was due to volatilization of DMMP from the coupons or a 

combination of degradation and hydrolysis due to the high 

RH in the chamber. Statistical analysis of the data was used 

to determine whether there was a statistically significant 

difference attributable to the ClO2 decontamination treatment. 

For malathion, it was readily evident that the 

decontamination with fumigant ClO2 resulted in a significant 

decrease in the amount of the TIC remaining on the coupons. 

Without decontamination, most of the malathion remained on 

the coupon; and with decontamination less than 1% remained 

on the laminate and approximately 25% remained on the 

carpet after 7 h.

The recoveries of DMMP and malathion on these coupons, 

normalized to the recoveries at 0 h, are presented in 

Appendix A, Table A-1 of this report. These normalized data 

were used as the input to the statistical analyses described 

below. The statistical analyses are more informative than the 

normalized recovery data, in that they provide insight into 

whether there is a statistical difference between recoveries 

with and without decontamination. Therefore, to avoid 

confusion by the presentation of somewhat repetitive, but not 

identical data here in the body of the report, the normalized 

recovery data are presented in the appendix. 

4.1.4 Statistical Analysis of Recovery Trends and 

Decontamination Efficacy

Statistical analysis was performed using recovery values 

(i.e., measured recovery results normalized to the Time 

0 recovery) to evaluate whether there were statically 

significant differences in the TICs recovered from treated 

coupons compared to controls. For each TIC and material 

combination, an analysis of variance (ANOVA) model was fit 

to the data. The form of the model was:

Yijt = μ + treatmentj

 + timet + (treatmentj * timet) + εijt (11)

where Yijt is the recovery for the ith coupon (i=1 to 5) in 

treatment group j (with or without decontamination) at time 

t (1, 3, or 7 h), μ is an overall constant, and εijt is the random 

error left unexplained by the model, assumed to be normally 

distributed with mean 0 and variance σ2.

The model included a fixed effect for type of treatment (with 

or without decontamination) and time (number of hours 

after application). A treatment by time interaction effect 

was also included if significant. For the TIC analysis, the 

interaction term was significant for all TIC and material 

combinations except for DMMP on carpet. The model above 

was fit in SAS® v9.1 using PROC GLM. Model diagnostics 

were evaluated to assure that there were no outliers, that the 

residuals were approximately normally distributed about the 

effect means, and that the assumption of consistent variance 

Table 4-5. Mean Recovery of TICs from Building Materials over Time 

With and Without Sabre ClO2 Fumigant Decontamination

TIC Material Time (n)

Mean Recovery, % ± SDa

Without

decontamination

With

decontamination

DMMP

Carpet

0 h (n = 3) 97 ± 4 84 ± 9b

1 h (n = 5) 32 ± 2 36 ± 5

3 h (n = 5) 24 ± 3 24 ± 5

7 h (n = 5) 15 ± 3 19 ± 3

Ceiling tile

0 h (n = 3) 102 ± 2 105 ± 1 b

1 h (n = 5) 40 ± 4 31 ± 2

3 h (n = 5) 28 ± 1 16 ± 1

7 h (n = 5) 13 ± 1 9.1 ± 0.4

Malathion

Carpet

0 h (n = 3) 112 ± 15 95 ± 3 b

1 h (n = 5) 100 ± 3 72 ± 3

3 h (n = 5) 102 ± 3 49 ± 4

7 h (n = 5) 98 ± 1 23 ± 2

Laminate

0 h (n = 3) 125 ± 1 105 ± 16 b

1 h (n = 5) 126 ± 15 30 ± 20

3 h (n = 5) 115 ± 7 3.4 ± 1.6

7 h (n = 5) 118 ± 13 0.4 ± 0.2

a) Calculated using Eq (6)

b) 0 h coupons were positive controls that were not exposed to fumigation
20

for the groups was appropriate. For DMMP on ceiling tile 

and malathion on laminate, the variability in recovery from 

replicate coupon at a given treatment and variability in time 

means was too large to meet the homogeneous error variance 

assumption of the model above. Instead, these data were fit 

to a heterogeneous variance model with the same effects but 

with separate variance terms for each treatment group and 

time. This model was fit in PROC MIXED. 

From the model output, mean recovery and corresponding 

confidence intervals were calculated for each treatment and 

time. The difference (and corresponding confidence interval) 

in mean recovery between the two treatments (with and 

without decontamination) was calculated at each time point. 

The three time point comparisons between the treatment 

groups were evaluated at joint 95% confidence. Using a 

Bonferroni approach, this resulted in each separate time point 

comparison being made at 98.3% confidence. The exception 

here was for DMMP on carpet, where the lack of a significant 

interaction term meant that a single estimated comparison 

(at 95% confidence) of with and without decontamination 

applied to all three time points. 

Table 4-6 shows the statistically-modeled, Eq (11), recovery 

results and the resulting calculation of decontamination 

efficacy. For the ANOVA modeling, the recovery data, 

shown in Table 4-6, were normalized relative to the 

recovery from the 0 h positive control, i.e., the recovery 

for 0 h positive controls is assumed to be 100%. The 

decontamination efficacy values are calculated with reference 

to the equivalent recovery in the humid air control chamber 

tests so as to account for the efficacy due solely to the 

fumigant ClO2

. Those results where there was a statistically 

significant difference between decontamination and without 

decontamination are highlighted in bold. 

Recoveries of DMMP from carpet coupons with and without 

exposure to the Sabre ClO2 fumigant decontamination 

steadily declined over the 7 h of testing. There were no 

statistically significant differences between recoveries of 

DMMP from carpet coupons without decontamination 

compared to the recoveries from coupons with 

decontamination. No decontamination efficacy was observed 

for ClO2 fumigation of DMMP on carpet. 

Recoveries of DMMP from ceiling tile coupons with 

and without exposure to the Sabre ClO2 fumigant 

decontamination steadily declined over the 7 h of testing. The 

Sabre decontamination recoveries were slightly lower than 

the recoveries without decontamination, and the difference 

was statistically significant at each test point. Although 

statistically significant, the small differences may not be of 

practical significance.

For malathion on carpet, the Sabre ClO2 fumigant 

decontamination resulted in a steady decline from 76% at 1 

h to 24% recovery at 7 h. Coupons without decontamination 

showed very little reduction in recovery over the 7 h of 

testing, with recoveries being in excess of 90% over this time 

period. The Sabre decontamination recovery was therefore 

statistically significantly less than the recovery without 

decontamination for all three time periods.

Table 4-6. Statistically Modeled, Eq (11), Percent Recovery of TICs With and Without Sabre ClO2

Fumigant Decontamination and Decontamination Efficacy

TIC Material Time Recovery, % (Confidence Interval) Decontamination

Without decontamination With decontamination Efficacy, %a

DMMP

Carpetb

1 h 35 (33–38) 42 (40–45) No efficacyc

3 h 23 (20–25) 30 (27–32) No efficacy

7 h 15 (13–18) 22 (20–25) No efficacy

Ceiling tiled

1 h 39 (30–48) 30 (26–34) 23% e

3 h 28 (25–30) 15 (14–16) 46%

7 h 12 (10–15) 8.7 (8.1–9.3) 28%

Malathion

Carpetd

1 h 89 (86–93) 76 (73–80) 15%

3 h 90 (87–94) 51 (48–55) 43%

7 h 87 (83–91) 24 (20–27) 72%

Laminated

1 h 100 (80–121) 28 (-4.7–61) 72%

3 h 91 (82–101) 3.3 (0.5–6.0) 96%

7 h 94 (76–112) 0.4 (0.1–0.7) 99.6%

a) Calculated using Eq (8)

b) Intervals are 95% confidence

c) No decontamination efficacy demonstrated; recovery with decontamination greater than recovery without 

decontamination 

d) Intervals are 98.33% confidence to control error rate at 5% for all three time point comparisons of treatment to control 

with the TIC and material combination

e) Decontamination efficacy shown in bold indicates a statistically significant difference in recovery with and without 

decontamination (p ≤ 0.05)
21

For malathion on laminate, the Sabre ClO2 fumigant 

decontamination resulted in a rapid decline from 28% at 1 h 

to 0.4% recovery at 7 h. Coupons without decontamination 

showed very little reduction in recovery over the 7 h of 

testing, with recoveries in excess of 90% over this time 

period. The Sabre decontamination recovery was therefore 

statistically significantly less than the recovery without 

decontamination for all three time periods. These trends are 

shown graphically in Figures 4-1 and 4-2 for DMMP and 

malathion, respectively.

The Sabre ClO2 fumigation was shown to be more effective 

at removing malathion than DMMP. Sabre ClO2 fumigation 

exhibits a significant and potentially useful level of 

decontamination efficacy against malathion on both carpet 

and laminate. There were differences between carpet and 

laminate in the ClO2 decontamination efficacy against 

malathion. The results show that Sabre ClO2 exhibits little 

or no potentially useful decontamination efficacy against 

DMMP on either carpet or ceiling tile. 

S Denotes persistance statistically significantly less with Sabre CIO2 fumigation decontamination

Figure 4-1. Statistically Modeled Percent Recovery Data for DMMP on Coupons With and 

Without Sabre ClO2 Fumigant Decontamination (Error Bars Show 95% Confidence Interval)

S Denotes recovery statistically significantly less with Sabre CIO2 fumigant decontamination

Figure 4-2. Statistically Modeled Percent Recovery Data for Malathion on Coupons With and 

Without Sabre ClO2 Fumigant Decontamination (Error Bars Show 95% Confidence Interval)
22

4.1.5 TICs on Laboratory, Handling, and Procedural 

Blank Coupons

There were three different types of blank coupons employed 

in the investigation of the Sabre decontamination technology. 

The laboratory blank coupon of each material was taken from 

storage directly to an extraction vial and was not exposed to 

the fume hood where the TICs were spiked. The handling 

blanks were placed in the fume hood during sample spiking 

and were then loaded into vials and sealed. At the designated 

times when coupons were removed from the chamber, one 

of these handling blanks was also removed from its sealed 

vial for extraction. The procedural blanks were also placed in 

the fume hood during sample spiking. These blank coupons 

were then placed into the test chambers along with the spiked 

samples, exposed to the fumigation treatment, and removed 

at the designated times with deliberately spiked coupons.

The levels of the TICs on the laboratory, handling, and 

procedural blank coupons are listed in Table 4-7. Due to 

similarity in levels on the laboratory and handling blanks, 

these data were averaged. Because the procedural blanks 

show specific trends in the transfer and deposition of material 

to clean surfaces in the chamber, the procedural blank 

data are presented individually for the experiments with or 

without decontamination, and also individually for each 

sampling time.

As described previously, the laboratory and handling coupons 

were never in the chamber, while the procedural coupons 

were blank coupons that were placed in the chamber at 

the beginning of an experiment. Any level of TIC found 

on a procedural blank coupon above the handling coupon 

blank level had to have arisen from redistribution of TICs 

in the chamber. The levels of DMMP recovered from the 

procedural blanks were approximately 10 fold higher than 

the background levels recovered from the laboratory and 

handling blanks. This appears to arise from volatilization of 

DMMP from spiked coupons and redeposition onto initially 

clean surfaces in the test or control chamber. Higher levels of 

DMMP were recovered from ceiling tile (12.0 μg) than carpet 

(3.41 μg) after being exposed to the fumigation treatment for 

7 h. The recovery of DMMP from procedural blanks did not 

impact recovery calculations. However, the contamination 

was recorded and analyzed as an experimental result. No 

corrective action was deemed necessary.

For malathion, which is considerably less volatile than 

DMMP, the malathion detected on the procedural blanks was 

within 2 SD of the mean mass measured on the handling and 

laboratory blanks (not significantly different).

Because there was only one procedural blank coupon at 

each sampling interval, it is difficult to determine whether 

there was a statistical difference in the levels found on 

these coupons for coupons collected with and without the 

ClO2

 decontamination — with exception of DMMP on the 

ceiling tile coupons. The mass of DMMP recovered from 

procedural blank coupons subjected to decontamination were 

approximately two to three times lower than the amounts 

recovered from similar procedural blank coupons that were 

not subjected to decontamination.

Table 4-7. Mean TIC Levels on Laboratory, Handling, and Procedural 

Blank Coupons

TIC Material Time Mean Mass on Lab/Handling Blanks, μg

DMMP Carpet 0–7 h 0.20 ± 0.34 (n = 8)

Ceiling tile 0–7 h 0.16 ± 0.04 (n = 8)

Malathion Carpet 0–7 h 0.65 ± 0.43 (n = 8)

Laminate 0–7 h 0.06 ± 0.06 (n = 8)

Mean Mass on Procedural Blanks, μg

Without 

Decontamination

With 

Decontamination

DMMP

Carpet

1 h 2.14 1.81

3 h 2.79 2.35

7 h 3.32 3.41

Ceiling tile

1 h 17.0 6.22

3 h 26.7 11.7

7 h 31.87 12.0

Malathion

Carpet

1 h 1.37 0.97

3 h 1.24 1.00

7 h 1.20 0.97

Laminate

1 h ND, <0.05a 0.07

3 h ND, <0.05 0.22

7 h ND, <0.05 0.25

a) ND = not detected; less than stated MDL
23

4.1.6 TICs in Chamber Air

The concentrations of the TICs in the vapor phase of the test 

chamber under near-static conditions are listed in Table 4-8. 

This air concentration is also listed as a percentage of mass 

applied onto the coupons. 

The relatively high air level of DMMP and the relatively 

low air level of malathion, in the chambers that did not 

undergo decontamination may be a reflection of the relative 

vapor pressures of the two TICs. In the decontamination 

chambers, though, it was evident that the fumigant ClO2

decreased the amount of both TICs in air. (The higher 

DMMP concentrations are observed even though the air 

exchange for malathion was high [one air exchange h-1

conditions] compared to the static air conditions for DMMP.) 

This effect was more pronounced for DMMP since the 

vapor phase levels were detectable both with and without 

decontamination. It was interesting to note that with DMMP, 

fumigant ClO2 had a greater decontamination effect on 

vapor phase material than on the residues on the coupons. 

The recovery of DMMP on the coupons was nearly identical 

whether exposed to fumigant ClO2 or not. These air data 

demonstrated that the fumigant appeared to markedly lower 

the gas phase levels of DMMP. One caveat applied to the air 

data collected during decontamination testing is that there 

were no preliminary recovery tests carried out to determine 

the stability of the TICs on Tenax® in the presence of vapor 

phase ClO2. Thus, these air levels may represent only a 

portion of the amount present in the chamber.

4.1.7 Detection of Oxidized Malathion Product on 

Coupons

To evaluate the usefulness of a decontamination procedure 

against chemical compounds, it is important to determine 

whether toxic by-products are produced. The extracts of 

selected carpet and laminate samples were analyzed for the 

presence of one potential oxidation product of malathion, 

malathion oxon (or maloxon). In maloxon, the P=S portion of 

the thiophosphate group on malathion is replaced with P=O, 

so that the molecule becomes an organophosphate, rather 

than a thiophosphate. Organophosphates are generally more 

toxic than the corresponding thiophosphate. 

One of each of the three positive controls (spiked with 

malathion, but not decontaminated) for each coupon type 

(carpet and laminate) was removed from the chamber 

after 1, 3, and 7 h and analyzed. Recoveries of maloxon 

were assumed to be the same as for malathion. Moreover, 

calibration curves were prepared from maloxon standards and 

other QC criteria were similar to those applied to the TICs. 

Maloxon was not detected on any of the positive controls. 

In addition, three carpet and three laminate test coupon 

extracts were similarly analyzed (one each from the 1, 3, and 

7 h decontamination tests). For both coupon types, maloxon 

was detected at levels corresponding to malathion to maloxon 

conversion percentages that increased in linear proportion to 

the log of the concentration multiplied by contact time (CT) 

of ClO2

 to which the coupons were exposed. The results are 

presented in Table 4-9 and Figure 4-3 (on page 24). 

Table 4-8. Mean Concentration of TICs in Test Chamber Air

TIC Material Time Mean Air Concentration, μg m-3 (% of Mass Applied)a, b

Without Decontamination (n = 2) With Decontamination (n = 2)

DMMP Carpet 0–1 h 1740 ± 13 (10%) ND, <3.6 (n = 1) (0.7%)

Ceiling tile 0–1 h 1430 ± 253 (9%) 484 (n = 1) (2.9%)

Malathion Carpet 1–3 h 0.42 ± 0.00 (<0.01%)c ND, <0.26 (<0.01%)

Laminate 1–3 h 0.42 ± 0.00 (<0.01%)c ND, <0.26 (<0.01%)

a) Air concentration expressed as percentage of total amount of TIC in the chamber if there had been no hydrolysis or 

degradation of the TIC

b) Calculated using Eq (10)

c) This sample was collected from the test chamber under one air exchange h-1 conditions; samples were not collected 

from the test chamber under near-static conditions

Table 4-9. Mean Mass of Malathion Oxidized to Maloxon by Coupon Type and ClO2 CT

Coupon Type Decontamination 

Time, h

ClO CT, 2

ppm-h

Maloxon 

Recovered, μg

Malathion 

Converted, μg

% Malathion 

Oxidized to Maloxon

Carpet

1 3366 78 82 16

3 9494 143 150 30

7 21,343 205 215 43

Laminate

1 2926 215 226 45

3 8941 297 312 62

7 21,076 338 355 71
24

Figure 4-3. Percent Oxidation of Malathion to Maloxon by Coupon Type and ClO2 Dosage

4.1.8 Condition of ClO2-Treated Coupons after Six 

Months 

To assess the effect of fumigant ClO2 on long-term stability 

and integrity of building materials, eight laboratory blanks 

(not exposed to ClO2) and 24 procedural blanks (exposed to 

ClO2) were maintained under ambient temperature and RH 

conditions in open vials for extended periods of time. After 

three months, and then again after six months, the coupons 

were inspected to assess any changes in appearance or 

structural integrity. The coupons were relatively unchanged 

after three months, and the carpet showed some minor 

“bleaching” after six months.

4.2 Results for Fumigant ClO2 Decontamination 

of CWAs

4.2.1 Analytical Method Results

The recoveries of the CWAs spiked onto the various coupon 

materials were not replicated after the initial assessment. The 

analytical method recoveries listed in Table 4-10 (on page 

25) are those that were determined prior to decontamination 

tests, and are presented here as a baseline against which the 

subsequent decontamination recovery data can be compared.

The approximate MDLs for the CWAs are listed in Table 

4-11 (on page 25). Each MDL was estimated based on the 

peak area of the lowest calibration standard, the signal to 

noise ratio for this concentration, and the peak area that 

could be integrated reliably for any peak with the data 

system.

4.2.2 Recovery over Time of CWAs on Building 

Materials With and Without Sabre ClO2 Fumigant 

Decontamination

Side-by-side chambers were installed in the laboratory for 

these tests, with one chamber (test) having fumigant ClO2

decontamination and the matching chamber (control) having 

no ClO2. The side-by-side design was adopted because of the 

high volatility of GB and TGD; with this design, any slight 

variation in laboratory temperature would be eliminated as a 

variable when assessing decontamination efficacy. A single 

spiked coupon of each type was analyzed directly after 

spiking to establish the baseline recovery. The recoveries of 

the CWAs from coupons at initiation (0 h) and at subsequent 

times (1 h and 2 or 4 h, depending on CWA) are listed in 

Table 4-12 (on page 25). The recoveries at initiation (0 h) 

for TGD from carpet, laminate, and ductwork, and these 

recoveries of VX from carpet and ductwork do not agree 

very well with the recoveries shown in Table 4-10 (on page 

25) (analytical method recoveries). In theory, these two 

values should have been very similar. At this time, there is 

no apparent reason for the difference, and the difference is 

simply noted here.

In many cases there were measurements made close to the 

detection limit. When there was at least one detected sample 

out of the five replicates, the median value of the sample 

set is reported along with the range, where a non-detectable 

value is reported as less than the MDL. When all five samples 

had non-detectable values, the percent recovery was reported 

as less than the MDL. In addition, the number of nondetected samples in each set of five replicates is also

noted in Table 4-12 (on page 25). 
25

Table 4-10. Mean Recovery of CWAs and SRS from Building Materials

Material Evaporation 

Time

Mean Recovery from 

Building Materials, % ± SDa

SRS/CWA 

Recovery 

Ratiob CWA SRS

GB TBP

Carpet 7 min 91 ± 12 87 ± 14 0.96

TGD TBP

Carpet 5 min 88 ± 18 98 ± 11 1.11

Laminate 5 min 97 ± 8 89 ± 9 0.92

Metal ductwork 5 min 98 ± 11 88 ± 10 0.90

VX TBP

Carpet 5 min 113 ± 9 103 ± 21 0.91

Laminate 5 min 107 ± 6 93 ± 14 0.87

Metal ductwork 5 min 110 ± 6 94 ± 15 0.85

a) Calculated using Eq (4)

b) Calculated using Eq (5)

Table 4-11. MDLs for CWAs

MDL

GB TGD VX

In solution 0.1 μg mL-1 0.1 μg mL-1 0.7 μg mL-1

On coupon 1 μg 1 μg 7 μg

Table 4-12. Average Recovery of CWAs from Building Materials over Time With 

and Without Sabre ClO2 Fumigant Decontamination

CWA Material Time, h (n) Average Recovery, % ± SDa

Without Decontamination With Decontamination

GB Carpet

0 h (n = 1) 87 NAb

1 h (n = 5) 5.1 ± 0.9 (0)c 3.6 ± 1.8 (0)c

4 h (n = 5) 4.9 ± 0.2 (0) 2.8 ± 0.9 (0)

TGD

Carpet

0 h (n = 1) 52 NA

1 h (n = 5) 40 ± 8.7 (0) 15 ± 2.7 (0)

2 h (n = 5) 30 ± 3.2 (0) 19 ± 8.8 (0)

Laminate

0 h (n = 1) 89 NA

1 h (n = 5) 1.3 (<0.1 – 3.6) (1)e 5.4 ± 6.1 (0)

2 h (n = 5) 0.4 (<0.1 – 3.2) (2) e < 0.1 (0.1 – 0.3) (4)e

Ductwork

0 h (n = 1) 73 NA

1 h (n = 5) 16 ± 5.5 (0) 10 ± 7.9 (0)

2 h (n = 5) 4.3 ± 1.9 (0) 5.4 ± 6.5 (0)

VX

Carpet

0 h (n = 1) 74 NA

1 h (n = 5) 77 ± 23 (0) <0.7 (5)d

4 h (n = 5) 72 ± 7.1 (0) <0.7 (5)d

Laminate

0 h (n = 1) 94 NA

1 h (n = 5) 81 ± 7.6 (0) <0.7 (5)d

4 h (n = 5) 88 ± 5.1 (0) <0.7 (5)d

Ductwork

0 h (n = 1) 84 NA

1 h (n = 5) 84 ± 2.6 (0) <0.7 (5)d

4 h (n = 5) 85 ± 7.6 (0) <0.7 (5)d

a) Calculated using Eq (6) except where non-detects occur, and only the median and range of 

values is shown

b) NA = not applicable; Time 0 coupons did not have decontamination

c) The number of non-detects is shown in parenthesis 

d) All coupons less than stated MDL; value shown is MDL as percentage of mass applied

e) Non-detects occurred – only the median and range of values is shown
26

Measurable amounts of all CWAs were removed from 

all building materials with the fumigant ClO2 treatment. 

However, for both GB and TGD, there was also a substantial 

decrease in the amount found on coupons that did not 

undergo ClO2 treatment. In these cases, statistical analysis 

of the data was the only way to accurately assess whether 

the slight differences could be attributable to the ClO2

treatment. Other physical processes such as volatilization 

and redistribution to the chamber and/or aqueous hydrolysis 

could account for the losses, as both chambers were operated 

under conditions of 80% RH. The case for VX is much more 

straight-forward. The VX persisted on the coupons which 

did not have decontamination treatment, in spite of the high 

RH of the control chamber; in contrast, VX was not detected 

on the coupons that were treated with the fumigant ClO2

process.

The recoveries of GB, TGD, and VX, normalized to the 

recoveries at 0 h, are presented in Appendix A, Table A-2 

of this report. These normalized data were used as the input 

to the statistical analyses described below. The statistical 

analyses are more informative than the normalized recovery 

data, in that they provide insight into whether there is a 

statistical difference between recoveries with and without 

decontamination; therefore, to avoid presentation of 

somewhat repetitive data here in the body of the report, the 

normalized recovery data are presented in the appendix.

4.2.3 Statistical Analysis of Recovery Trends and 

Fumigant Decontamination Efficacy

Statistical analysis was performed using recovery values 

(i.e., measured recovery results normalized to the Time 0 

recovery) to evaluate whether there were statically significant 

differences in the CWA recovered from treated coupons 

compared to controls. Because the recoveries are normalized 

to the Time 0 recovery value, it is possible to obtain recovery 

values that are greater than 100%. Values above 100% were 

left as calculated, though they should be interpreted in the 

context they were created, and not truly greater than 100%.

For CWA and material combinations with detectable 

recoveries on coupons with and without decontamination, 

an ANOVA model was fit to the data. The model included 

a fixed effect for type of treatment (with or without 

decontamination) and time (number of h after application). 

A treatment by time interaction effect was also included if 

significant. The model was fit in SAS® v9.1 using PROC 

MIXED. Model diagnostics were evaluated to assure that 

there were no outliers, that the residuals were approximately 

normally distributed about the effect means, and that the 

assumption of consistent variance for the groups was 

appropriate.

From the model output, mean recovery and corresponding 

confidence intervals were calculated for each treatment and 

time. The difference (and corresponding confidence interval) 

in mean recovery between the two treatments (with and 

without decontamination) was calculated at each time point. 

The two time point comparisons between the treatment 

groups were evaluated at joint 95% confidence, so each 

separate comparison is essentially approximately 97.5% 

confidence.

For CWA and material combinations with non-detects, e.g., 

TGD on laminate, the ANOVA approach is not appropriate 

since the data are censored and may violate the assumptions 

of normality and constant variance. Instead, a less constrained 

non-parametric analysis was performed. Consistent with this 

type of analysis, median (rather than mean) recovery was 

reported for each treatment and time point. In cases where the 

median value was a non-detect (i.e., three or more of the five 

replicate coupons were non-detects), the results are reported 

as “ND <MDL”. To assess the effectiveness of the treatment 

at each time point, the median recovery with and without the 

Sabre decontamination were compared using the WilcoxonMann-Whitney test to determine whether the observed 

median with decontamination is significantly different from 

the median without decontamination. The Wilcoxon-MannWhitney test uses ranks of data to test whether two samples 

are significantly different. A corresponding estimate of the 

shift in recovery and accompanying 95% confidence interval 

were formed with the Hodges-Lehmann procedure which is 

appropriate for rank order data, such as the medians. These 

statistical estimates were performed in StatXAct® v7. To 

perform this analysis, non-detect values were set equal to half 

the MDL. To estimate the decontamination efficacy when the 

CWA was not detected, the MDL was used in the calculation.

Table 4-13 (on page 27) shows the recovery results, with 

the confidence interval, from the statistical analysis. The 

table also shows the decontamination efficacy for Sabre 

decontamination as compared with exposure of the CWAs 

to humidified air (without decontamination). Those results 

where there was a statistically significant difference between 

decontamination and no decontamination are highlighted in 

bold. 

For GB and TGD on carpet, and TGD on metal, the results 

were obtained with the ANOVA approach defined above. The 

recovery for GB on carpet was low for coupons with and 

without fumigant ClO2 decontamination at both 1 and 4 h. 

However, the recovery with decontamination was statistically 

less than without decontamination so that it can be concluded 

the fumigant ClO2

 decontamination was more effective than 

no decontamination (2.1 percentage points at 1 h and 2.2 

percentage points at 4 h).

The recovery of TGD on carpet was statistically significantly 

less (48 percentage points at 1 h and 21 percentage points at 

2 h) in the coupons with fumigant ClO2 decontamination than 

without decontamination.

The recovery of TGD on metal decreased over time for 

both the fumigant ClO2 decontaminated coupons and the 

coupons without decontamination. The recovery with ClO2

decontamination was not statistically significantly different 

than recovery without decontamination.
27

Table 4-13. Statistically Modeled, Eq (11), Percent Recovery of CWAs With and Without 

Sabre ClO Fumigant Decontamination and Decontamination Efficacy 2

CWA

GB

TGD

VX

Material

Carpetb

Carpetb

Laminated

Ductworkb

Carpetd

Laminated

Ductworkd

Recovery, % (Confidence Interval) Decontamination Time

Without Decontamination With Decontamination Efficacy, %a

1 h 6.1 (5.1-7.1) 4.0 (2.9-5.0) 34%c

4 h 5.6 (4.5-6.6) 3.4 (2.1-4.8) 39%

1 h 77 (63-91) 29 (15-43) 62%

2 h 57 (43-71) 36 (21-50) 37%

1 h 1.4 3.2 No efficacye

2 h 0.5 ND, <0.1f No efficacyg

1 h 21 (13-30) 14 (4.7-23) No efficacyg

4 h 5.9 (0-15) 7.4 (0-16) No efficacye

1 h 102 ND, <0.7 >99%

4 h 97 ND, <0.7 >99%

1 h 89 ND, <0.7 >99%

4 h 91 ND, <0.7 >99%

1 h 99 ND, <0.7 >99%

4 h 105 ND, <0.7 >99%

a) Calculated using Eq (6)

b) Reported values are least square means; intervals are joint 95% confidence across time points for the combination 

of the CWA and the material

c) Decontamination efficacy shown in bold indicates a statistically significant difference in recovery with and without 

decontamination (p ≤ 0.05)

d) Reported values are medians; ND denotes median value is a non-detect; difference interval is Hodges-Lehmann 

median shift interval of 95% confidence

e) No decontamination efficacy demonstrated; recovery with decontamination greater than recovery without 

decontamination 

f) ND = not detected; less than coupon MDL converted to percentage of spike amount

g) No statistically significant decontamination demonstrated

For TGD on laminate, and VX on carpet, laminate, and 

metal, the results were obtained with the nonparametric 

approach described above.

TGD on laminate exhibited almost complete removal at 

both time points for coupons with and without fumigant 

ClO2 decontamination. No statistically significant difference 

in recovery was observed for the decontaminated coupons 

compared to the coupons without ClO2 decontamination at 

time 1 h (p=0.15) or at 2 h (p=0.17).

For VX on carpet, metal, and laminate, the coupons 

without decontamination exhibited very high recovery at 

each time point, while the fumigant ClO2 decontaminated 

coupons showed removal to below the MDL in every case. 

With p-values of 0.008 for each comparison, the recovery 

under the fumigant ClO2 decontamination was statistically 

significantly less than the recovery without decontamination. 

The estimated median differences in fumigant ClO2

decontamination reduction of VX recovery range from 

88 percentage points (VX, laminate, 1 h) to 105 percentage 

points (VX, metal, 4 h). 

The recovery of GB, TGD, and VX on the different 

materials is shown graphically in Figures 4-4, 4-5, 

and 4-6, respectively (on pages 28 amd 29).
28

S S

0.1

1

10

100

Recovery (%)

With Decon Without Decon

S Denotes recovery statistically significantly less w ith Sabre ClO2 

 Carpet 

 1 h

 Carpet 

 4 h

Figure 4-4. GB Recovery (%) on Coupons With and Without Sabre ClO2

Fumigant Decontamination (Error Bars Show 95% Confidence Interval)

S Denotes recovery statistically significantly less with Sabre CIO2

S S

N D

1/2 M D L

0.01

0.1

1

10

100

 Recovery (%)

With Decon Without Decon

 Carpet Laminate Metal

 1 h

Values show n w ithout error bars are medians rather than means due to nonparametric statistical model fit to data w ith 

non-detects

S Denotes recovery statistically significantly less w ith Sabre ClO2 fumigant decontamination

 Carpet Laminate Metal

 2 h

Figure 4-5. TGD Recovery (%) on Coupons With and Without Sabre ClO2

Fumigant Decontamination (Error Bars Show 95% Confidence Interval)

Values shown without errors bars are medians rather than means due to nonparametric statistical 

model fit to data with non-detects.

S Denotes recovery statistically significantly less with Sabre CIO2 fumigant decontamination
29

ND

1/2 M DL

ND

1/2 M DL

ND

1/2 M DL

ND

1/2 M DL

ND

1/2 M DL

ND

1/2 M DL

0.1

1

10

100

Recovery (%)

With Decon Without Decon

S S S S S S

Carpet Laminate Metal

 1 h

Carpet Laminate Metal

 4 h

Figure 4-6. VX Recovery (%) on Coupons With and Without Sabre 

ClO2 Fumigant Decontamination

Values shown are medians rather than means due to nonparametric statistical model fit to data with non-detects.

S Denotes recovery statistically significantly less with Sabre CIO2 fumigant decontamination
30

4.2.4 CWAs on Laboratory and Procedural Blank 

Coupons

There were two different types of blank coupons employed 

in the investigation of the Sabre decontamination technology. 

The laboratory blank coupon of each material was taken from 

storage directly to an extraction vial and was not exposed to 

the fume hood where the TICs were spiked. The procedural 

blanks were placed in the fume hood during sample spiking. 

These blank coupons were then placed into the test chambers 

along with the spiked samples, and removed at the designated 

times with coupons. These procedural blanks were expected 

to show the extent to which volatilization and redeposition 

onto other surfaces may account for some of the losses 

from coupons. Table 4-14 shows the amounts of the CWAs 

measured on these different blanks.

As was observed with the TICs, the data in Table 4-14 

indicate that GB and TGD, which are more volatile than 

VX, may migrate from the initially spiked coupons to other 

surfaces in the chamber, including the procedural blank 

coupons. For TGD, the carpet coupons absorbed considerably 

more than the laminate or ductwork coupons.

4.2.5 Concentration of ClO2 in Test Chambers

The concentrations of ClO2 measured in the test chambers 

during decontamination of the three different CWAs are listed 

in Table 4-15.

Table 4-14. Comparison of Mean CWA Levels on Laboratory 

and Procedural Blank Coupons

CWA Material Time

Mean Mass on Blank, μg

Without 

Decontamination

With 

Decontamination

Laboratory 

Blank

Procedural 

Blank

Procedural 

Blank

GB Carpet

0 h ND, <1a NTb NT

1 h NT 17 5.1 

4 h NT 31 7.8 

TGD

Carpet

0 h ND, <1 NT NT

1 h NT 66 17 

2 h NT 179 27 

Laminate

0 h ND, <1 NT NT

1 h NT ND, <1 ND, <1

2 h NT ND, <1 ND, <1

Ductwork

0 h ND, <1 NT NT

1 h NT ND, <1 ND, <1

2 h NT ND, <1 ND, <1

VX

Carpet

0 h ND, <7 NT NT

1 h NT ND, <7 ND, <7

4 h NT 6.6 ND, <7

Laminate

0 h ND, <7 NT NT

1 h NT ND, <7 ND, <7

4 h NT 4.7 ND, <7

Ductwork

0 h ND, <7 NT NT

1 h NT ND, <7 ND, <7

4 h NT ND, <7 ND, <7

a) ND = not detected; less than stated MDL

b) NT = not tested at this time

Table 4-15. Mean Concentration of ClO2 in Test 

Chamber for CWA Decontamination Tests

CWA Time Mean ClO2 Concentration, ppm

GB

0–1 h 3100 ± 0 (n = 2)

0–4 h 2960 ± 80 (n = 6)

TGD 0–2 h 3020 ± 140 (n = 8)

VX

0–1 h 3120 ± 100 (n = 4)

0–4 h 3070 ± 170 (n = 9)
31

4.3 Results for Liquid Decontamination of CWAs

4.3.1 Recovery of CWAs from Liquid Decontamination 

Solutions

Initial tests were conducted to determine whether CWAs 

could be effectively recovered from liquid decontamination 

solutions or from neutralized liquid decontamination 

solutions. The purpose of the method development was to 

determine (1) the maximum percentage of spiked CWA 

that could be recovered from neutralized decontamination 

solution and (2) the percentage of spiked CWA recovered 

after 1 h in the decontamination solution. High recovery from 

the neutralized decontamination solution would indicate that 

the neutralization was effective and could be used to end the 

loss/degradation of the CWA caused by the decontamination 

solution. A high recovery of CWA from the decontamination 

solution after 1 h of contact would suggest that the 

decontamination was ineffective against the CWA.

Recovery of GB, TGD, and VX from 10% bleach (0.6% 

hypochlorite) and 3000 ppm ClO2 was tested, as was 

recovery from neutralized solutions that were created 

via addition of sodium thiosulfate to the bleach or ClO2

solutions. CWAs were held in decontamination solutions for 

1 h prior to addition of hexane for extraction and the addition 

of the SRS; the CWAs were held in the neutralized solutions 

for only 15 sec before addition of the SRS and hexane. The 

SRS (TBP used as SRS for all three CWAs) was spiked into 

the liquid decontamination or neutralized decontamination 

solution just prior to addition of hexane. Contact time for the 

SRS with any solution was approximately 15 sec. The results 

of these tests are shown in Table 4-16.

This investigation produced unexpected results. Clearly, 

the SRS is not completely similar to the CWAs in physicochemical properties. Either by virtue of slower aqueous 

hydrolysis or greater solubility in hexane, it is almost 

fully recovered from the neutralized solutions (neutralized 

bleach and neutralized ClO2). In contrast, recovery of GB 

and VX from neutralized solutions was less than 10%, and 

in some cases these compounds were not recovered at all; 

TGD recovery was approximately 50% from the neutralized 

solutions. Volatilization from the aqueous solution, rapid 

hydrolysis and/or poor extraction efficiency into hexane 

might explain the low recoveries of the CWAs from the 

neutralized solutions.

When comparing recoveries from neutralized solutions 

versus oxidant solutions, it appears that bleach is clearly 

effective in decontamination of TGD. The other cases are 

somewhat ambiguous because of the potential effect of 

aqueous hydrolysis or poor extraction efficiency. Because of 

the possibility that the small, polar CWAs were preferentially 

retained in the aqueous solution over the hexane, the 

decision was made to conduct liquid decontamination tests 

with coupons that would be removed from the liquid before 

extraction. In addition, the decision was made to collect and 

record the SRS recovery values (not reported here), but not to 

correct CWA recovery by the SRS recovery, as they appear to 

be quite dissimilar in recovery from aqueous media. The data 

suggest that SRS correction for recovery would not be useful. 

4.3.2 Recovery over Time of CWAs on Building Materials 

With and Without Liquid Decontamination

The recovery of CWAs from building materials 

immersed in bleach or ClO2 solutions was evaluated 

using decontamination times of 10 to 30 min because the 

results described in Section 4.3.1 suggested that complete 

decontamination could be expected in less than 1 h. In the 

preliminary solution tests described in Section 4.3.1, no 

efficacy of liquid ClO2 was observed against GB or TGD. 

Therefore, the decontamination of CWAs by liquid ClO2 was 

only tested against VX. In parallel with the VX tests, spiked 

coupons were placed in vials containing slightly acidic 

water (pH = 4.5–7). This differed from the liquid bleach 

decontamination testing where coupons not undergoing 

decontamination were placed in sealed vials without any 

liquid solution; initial tests showed that CWAs were largely 

destroyed by, or not recovered from, aqueous solution. 

Coupons without liquid ClO2 decontamination were placed in 

slightly acidified water (pH comparable to the ClO2 solution) 

with the hope that VX, which is known to be especially prone 

to hydrolysis under basic conditions, might be more stable in 

an acidic aqueous condition. 

Table 4-16. Mean Recovery of CWAs and SRS from Liquid Decontamination Solutions

Solution - Hold Time Before SRS Mean Recovery, % ± SD (n = 3)

Addition and Hexane Extraction CWA SRS Recovered From CWA Solution

GB TGD VX TBP (from GB) TBP (from TGD) TBP (from VX)

Bleach - 1 h ND, <0.1 ND, <0.1 ND, <0.7 96 ± 3 96 ± 2 97 ± 2

Neutralized bleach - 15 sec 1 ± 0 41 ± 10 ND, <0.7 87 ± 1 84 ± 2 86 ± 3

ClO - 1 h 8 ± 2 58 ± 5 ND, <0.7 91 ± 2 93 ± 1 89 ± 3 2

Neutralized ClO - 15 sec 8 ± 1 56 ± 10 ND, <0.7 75 ± 8 70 ± 23 60 ± 3 2

ND = not detected
32

Tables 4-17 and 4-18 show the recoveries of CWA from 

spiked coupons without decontamination (i.e., stored in 

sealed vials in air for the duration of the decontamination 

period), in acidified water, or in decontamination solutions 

(bleach or ClO2 solution), showed significant loss of VX; 

and VX was not recovered from any coupon with liquid 

ClO2 decontamination. Table 4-17 reports recoveries as a 

percentage of the mass of CWA spiked onto the coupons. 

Table 4-18 (on page 33) reports recoveries as a percentage 

of the Time 0 recoveries from spiked coupons.

In all cases with 30 min of the decontamination regimen, the 

CWAs were at non-detectable levels or had recoveries of less 

than one percent. These are impressive results, especially for 

the highly sorptive and large surface area carpet material. 

While these results show that there are non-detectable levels 

on the building material, this investigation did not explore 

the mechanism of this disappearance. The CWA may have 

undergone aqueous hydrolysis, in which case water might 

have been an equally effective decontamination agent. 

Alternatively, the CWAs may have been soluble in the bleach 

but not degraded. To fully understand the ramifications 

of this decontamination method, it may be necessary to 

measure both the CWAs and their degradation products 

directly (i.e., without extraction into organic solvent) in the 

decontamination solution. 

Because there was no effective control for the CWA solubility 

and/or aqueous hydrolysis, the decontamination efficacy of 

the bleach (specifically ClO-) was not calculated. Similarly, 

Table 4-17. Mean Recovery of CWAs from Building Materials after Various Treatments 

as Percent of Mass Applied

CWA Material Time

Mean CWA Recovery, % of Mass Appliede

 ± SD (n = 5)

Without 

Decontamination Acidified Water Bleach 

Decontamination

ClO2 Decontamination

GB Carpet

0 min 75 ± 5

Not tested; not included in test/QA plan for baseline 

bleach testing.

NAa

Not tested because no significant efficacy observed in 

solution testing.

10 min 70 ± 5 ND, <0.1b

20 min 66 ± 7 ND, <0.1

30 min 63 ± 1 ND, <0.1

TGD

Carpet

0 min 38 ± 4 NA

10 min 46 ± 13 ND, <0.1

20 min 53 ± 12 ND, <0.1

30 min 51 ± 18 ND, <0.1

Laminate

0 min 62 ± 13 NA

10 min 56 ± 6 2.3 ± 1.2

20 min 48 ± 9 1.1 ± 1.0

30 min 47 ± 10 0.1 ± 0.03

Ductwork

0 min 38 ± 15 NA

10 min 49 ± 15 1.2 ± 0.7

20 min 41 ± 17 0.2 ± 0.3

30 min 34 ± 11 0.3 ± 0.5

VX

Carpet

0 min 84 ± 5 77 ± 4 a NA NAb

10 min NTc 4.5 ± 1.1 ND, <0.7 ND, <0.7d

20 min NT 1.7 ± 0.4 ND, <0.7 ND, <0.7

30 min 90 ± 6 2.5 ± 0.5 ND, <0.7 ND, <0.7

Laminate

0 min 100 ± 5 111 ± 7 NA NA

10 min NT 2.1 ± 0.2 ND, <0.7 ND, <0.7

20 min NT 2.8 ± 1.4 ND, <0.7 ND, <0.7

30 min 102 ± 6 1.9 ± 0.3 ND, <0.7 ND, <0.7

Ductwork

0 min 101 ± 10 105 ± 8 NA NA

10 min NT 0.5 ± 0.2 ND, <0.7 ND, <0.7

20 min NT ND, <0.07 ND, <0.7 ND, <0.7

30 min 96 ± 11 ND, <0.07 ND, <0.7 ND, <0.7

a) NA = not applicable; no decontamination done at Time 0

b) ND = not detected; less than MDL converted to equivalent percentage

c) NT = not tested at this time interval

d) n = 4; one outlier

e) Recovery for individual coupons calculated in the same manner as analytical method recovery efficiency, Eq (4) for each 

individual coupon. The mean and SD of the recoveries for a given condition are reported here. 
33

there was no statistical modeling of the recovery. The raw 

data do, however, suggest that the decontamination with 

aqueous bleach was very effective.

Because the initial tests showed that CWAs were largely 

destroyed by, or not recovered from, aqueous solution, the 

control samples (without decontamination) were not placed 

in a liquid solution. Instead, the spiked coupons that did not 

receive the decontamination technology were allowed to 

remain in the laboratory fume hood until they were retrieved 

for extraction. Coupons were withdrawn from the liquid 

decontamination bath and the fume hood at nearly the same 

times. The wet coupons were shaken lightly to remove 

excess liquid, spiked with the SRS and then placed in the 

extraction vial with hexane for extraction. The recoveries 

of the CWAs mirrored the results obtained for the initial 1 h 

decontamination tests in that the CWAs were not recovered. 

However, this time, solubility in water cannot be suspected as 

the cause. 

The recoveries of VX on these coupons, normalized to the 

recoveries at 0 h, are presented in Appendix A, Table A-3 

of this report. These normalized data were used as the input 

to the statistical analyses described below. The statistical 

analyses are more informative than the normalized recovery 

data, in that they provide insight into whether there is a 

statistical difference between recoveries with and without 

decontamination; therefore, to avoid somewhat repetitive 

data, the normalized recovery data are presented in the 

appendix.

Table 4-18. Mean Recovery of CWAs from Building Materials After Various Treatments

as Percent of T0 Recovery

CWA Material Time

Normalized CWA Recovery, % of Mass Recovered at Time 0d

 ± SD (n = 5)

Without 

Decontamination

Acidified 

Water

Bleach

Decontamination

ClO2

Decontamination

GB Carpet

10 min 93 ± 7

Not tested; not included in test/QA 

plan for baseline testing.

ND, <0.1a

Not tested because no significant 

efficacy observed in solution testing.

20 min 88 ± 9 ND, <0.1

30 min 84 ± 2 ND, <0.1

TGD

Carpet

10 min 121 ± 33 ND, <0.1

20 min 139 ± 31 ND, <0.1

30 min 135 ± 47 0.1 ± 0.03

Laminate

10 min 90 ± 10 3.7 ± 1.9

20 min 77 ± 14 1.7 ± 1.7

30 min 77 ± 16 0.2 ± 0.1

Ductwork

10 min 130 ± 39 3.2 ± 1.9

20 min 109 ± 44 0.5 ± 0.7

30 min 91 ± 28 0.8 ± 1.2

VX

Carpet

10 min NTb 5.0 ND, <0.7 ND, <0.7c

20 min NT 2.2 ND, <0.7 ND, <0.7

30 min 107 ± 7 3.3 ND, <0.7 ND, <0.7

Laminate

10 min NT 1.9 ND, <0.7 ND, <0.7

20 min NT 1.9 ND, <0.7 ND, <0.7

30 min 102 ± 6 1.7 ND, <0.7 ND, <0.7

Ductwork

10 min NT ND, <0.7 ND, <0.7 ND, <0.7

20 min NT ND, <0.7 ND, <0.7 ND, <0.7

30 min 95 ± 11 ND, <0.7 ND, <0.7 ND, <0.7

a) ND = not detected, less than MDL converted to equivalent percentage
34

4.3.3 Statistical Analysis of Recovery Trends and Liquid 

Decontamination Efficacy

Statistical analysis was performed on the recovery results. 

For this investigation, liquid ClO2 decontamination was 

compared to coupons in acidified water. The residual VX on 

the surfaces was below the MDL for some samples without 

decontamination. For coupons with decontamination, VX 

was below the detection limit for every material (carpet, 

laminate, and ductwork). For this type of data, it is not 

appropriate to fit an ANOVA statistical model, since the 

data are censored and may violate the assumptions of 

normality and constant variance in an ANOVA. Instead, a 

less constrained non-parametric analysis was performed. 

Consistent with this type of analysis, median (rather than 

mean) recovery was reported for each treatment, material, 

and time point. In cases where the median value was a nondetect (i.e., three or more of the five replicate coupons were 

non-detects), the results are reported as “ND <MDL”. To 

assess the effectiveness of the treatment at each time point 

within each material, the median recovery with the ClO2

liquid decontamination and in acidified water were compared 

using the Wilcoxon-Mann-Whitney test. A corresponding 

estimate of the shift in recovery and accompanying 95% 

confidence interval were formed with the Hodges-Lehmann 

procedure. These statistical estimates were performed in 

StatXAct® v7. To perform this analysis, non-detect values 

were set equal to half the MDL.

Table 4-19 shows the recovery results from the statistical 

analysis. To calculate the decontamination efficacy, the MDL 

was used in the calculation.

For VX on carpet and laminate, at each of 10, 20, and 30 

min, the median recovery was below the MDL with the ClO2

liquid decontamination, while the median recovery without 

decontamination was between one and five percent. In each 

case, the recovery from a given material and at a given time 

point was statistically significantly lower (p=0.036) for the 

ClO2 liquid decontamination compared to recoveries from 

acidified water. Confidence intervals for these differences 

exhibited no quantifiable lower bound (i.e., negative infinity). 

For VX on metal, the ClO2 liquid decontamination coupon 

recovery values were all below the MDL at every time point. 

The same was true for every coupon except one at 10 min 

for coupons without decontamination. With the median 

recovery values below the MDL with and without liquid 

ClO2 decontamination on metal ductwork at all time points, 

the statistical tests were unable to conclude any difference 

in recovery between the treatments. These results are shown 

graphically in Figure 4-7 (on page 35).

Table 4-19. Statistically Modeled, Eq (11), Percent Recovery of VX With and Without Liquid ClO2

Decontamination and Decontamination Efficacy (Compared to Recovery from Acidified Water)

CWA

VX

Material

Carpet

Laminate

Ductwork

Time

10 min

20 min

30 min

10 min

20 min

30 min

10 min

20 min

30 min

Recovery as % of Time 0

Acidified Water With Decontamination

5.0 ND, <0.7

2.2 ND, <0.7

3.3 ND, <0.7

1.9 ND, <0.7

1.9 ND, <0.7

1.7 ND, <0.7

ND, <0.7 ND, <0.7

ND, <0.7 ND, <0.7

ND, <0.7 ND, <0.7

Decontamination 

Efficacy, %

>86%a

>68%

>79%

>63

>63

>59

Indeterminateb

Indeterminate

Indeterminate

a) Calculated using Eq (8); values given in bold are statistically significant

b) Efficacy cannot be determined due to non-detects both with and without decontamination
35

Values shown are medians rather than means due to nonparametric statistical model fit to data with non-detects

S Denotes recovery statistically significantly less with Sabre ClO2 fumigant decontamination

*Denotes non-detect, 1⁄2 MDL used in place of 0 in the analysis

Figure 4-7. Statistical Analysis Results of VX Decontamination with Liquid ClO2 

Table 4-20. CWA Levels on Laboratory and Procedural Blank Coupons with Bleach Decontamination

CWA Material Blank Type Time Mass, μg

GB Carpet Laboratory 0 min ND, <1a

Procedural 10, 20, 30 min ND, <1 

TGD

Carpet, Ductwork Laboratory 0 min ND, <1 

Procedural 10, 20, 30 min ND, <1 

Laminate

Laboratory 0 min ND, <1 

Procedural 10, 30 min ND, <1 

Procedural 20 min 0.9 

VX Carpet, Laminate, Ductwork Laboratory 0 min ND, <7 

Procedural 10, 20, 30 min ND, <7 

a) ND = not detected, less than stated MDL

b) NS = not spiked

4.3.4 CWAs on Laboratory and Procedural Blank 

Coupons During Liquid Decontamination Tests

There were two different types of blank samples collected 

during the liquid decontamination tests. The laboratory 

coupon blank of each material was taken from storage 

directly to an extraction vial and was not exposed to the 

fume hood where the spiking occurred. The procedural blank 

coupons were unspiked coupons present in the fume hood 

when the spiking was done; these blank coupons were then 

loaded into vials containing the decontamination solution. 

The blank coupons were retrieved for extraction and analysis 

at the same time as the spiked coupons.

The amounts of CWAs measured in the extracts of these 

blank coupons for bleach decontamination tests are listed 

in Table 4-20. With exception of one TGD detection at a 

very insignificant level, the CWAs were not detected on the 

laboratory or procedural blanks. 

For the decontamination tests with liquid ClO2

, there were no 

laboratory blanks analyzed, as these tests followed closely 
36

after the liquid bleach decontamination tests. The levels of 

CWAs on the procedural blank coupons acquired during the 

liquid ClO2 decontamination tests are listed in Table 4-21. VX 

was not detected on any of the procedural blanks.

After liquid decontamination of the test coupons, the 

decontaminated coupons were visually inspected; and any 

obvious changes in the coupon surfaces were recorded. 

When testing decontamination with liquid bleach, the control 

condition consisted of exposure to room air; when testing 

decontamination with liquid ClO2, the control condition 

consisted of exposure of coupons to slightly acidic water. 

No damage or visible change to any of the carpet, laminate 

or ductwork test coupons was observed comparing extracted 

laboratory blank coupons (not exposed to decontamination) 

to extracted procedural blank coupons (exposed to 

decontamination) directly after decontamination treatment. 

Coupons were not re-examined after 3 and 6 months for this 

part of the effort.

Table 4-21. VX Levels on Procedural Blank Coupons with Liquid ClO2 Decontamination

CWA Material Blank Type Time Mass, μg

VX Carpet, Laminate, Ductwork Procedural 10, 20, 30 min ND, <7a

a) ND = not detected, less than stated MDL
37

5.0

Summary

The effectiveness of fumigant ClO2, liquid ClO2, and 

liquid bleach decontamination technologies for selected 

TICs and/or CWAs was evaluated on building materials, 

specifically, carpet, ceiling tile, laminate, and ductwork. 

Table 5-1 is a summary of the recovery and decontamination 

efficacy results at the longest time interval tested for each 

combination of decontamination technology, TIC, or CWA, 

and building material. The recovery of each chemical is 

listed in this table for samples with decontamination or 

under positive control conditions (without decontamination 

or in acidified water). For instance, fumigant ClO2

decontamination was operated at about 80% RH; 

therefore the control conditions without decontamination 

consisted of coupons exposed to 80% RH air. Liquid ClO2

decontamination was in aqueous solution; therefore the 

control conditions without decontamination consisted of 

coupons in acidified water. With this design, comparing 

the recovery of a given chemical under the two conditions 

allowed assessment of the effectiveness of the ClO2 itself, 

rather than the combined effects of ClO2 and water (liquid or 

vapor), as many of these chemicals are susceptible to aqueous 

hydrolysis. 

For the fumigant ClO2 decontamination, it appears that this 

technology was most effective against malathion and VX. 

Because these chemicals persisted to a large extent in the 

presence of high RH under control conditions, it was clear 

Table 5-1. Summarization of Percent Recovery With and Without Decontamination 

Technologies, and Decontamination Efficacy for TICs and CWAs

Technology Chemical Material Duration Recovery, % Decontamination 

Without Decon With Decon Efficacy %a

Fumigant

ClO2

3000 ppm

Malathion Carpet 7 h 87g 24g 72

Laminate 7 h 94g 0.4g 99.6

DMMP Carpet 7 h 19g 22g No efficacyb

Ceiling tile 7 h 9.4g 8.7g 8

GB Carpet 4 h 5.6g 3.4g 39

TGD

Carpet 2 h 57g 36g 37

Laminate 2 h 0.5g <0.1c No efficacyf

Ductwork 2 h 5.9g 7.4g No efficacyb

VX

Carpet 4 h 97g <0.7 c >99

Laminate 4 h 91g <0.7 c >99

Ductwork 4 h 105g <0.7 c >99

Liquid

Bleach

GB Carpet 30 min 84h <0.1 c

Complete or nearly 

complete loss 

of recoverable 

CWA from 

treated compared 

with untreated 

couponsd

TGD

Carpet 30 min 135h 0.1

Laminate 30 min 77h 0.2

Ductwork 30 min 91h 0.8

VX

Carpet 30 min 107h <0.7 c

Laminate 30 min 102h <0.7 c

Ductwork 30 min 95h <0.7 c

Liquid

ClO2

VX

Carpet 30 min 3.3g <0.7 c >86

Laminate 30 min 1.7g <0.7 c >59

Ductwork 30 min <0.7 c <0.7 c NAe

a) Statistically significant decontamination efficacy between recovery with and without decontamination test 

conditions

b) No efficacy; recovery with decontamination is greater than recovery without decontamination

c) Not detected; MDL expressed as wpercentage of mass applied to the coupon 

d) While decontamination efficwacy may be high, efficacy due to the bleach effect cannot be distinguished from 

the effect of the water hydrolysis or dissolution because the control coupons were stored in room air

e) NA= not applicable; cannot calculate decontamination efficacy when the analyte is not detected under either 

the control or test conditions

f) No efficacy; no statistically significant differences in recovery with and without decontamination

g) Statistically modeled data using Eq (11)

h) Calculated using Eq (7)
38

that the ClO2, and not water, was responsible for degradation 

of these two compounds. The high volatilities of DMMP, 

GB, and TGD make it difficult to assess the effectiveness of 

fumigant ClO2 decontamination against these compounds. 

However, for DMMP where air levels were measured in both 

the test and control chambers, the considerable difference in 

these air levels suggested that fumigant ClO2 was responsible 

for decontamination of gas-phase DMMP; the loss of DMMP 

from surfaces may still be due to some extent to either 

volatilization or aqueous hydrolysis. However, the gas-phase 

decontamination may be a powerful technique for highly 

volatile compounds.

When testing with liquid bleach, the positive controls were 

not placed in any liquid solution. Based on findings from 

the bleach testing, the approach was revised for testing 

with liquid ClO2. For liquid ClO2 the control condition 

consisted of exposure of coupons to slightly acidic water. 

The test coupons and associated controls of the liquid 

decontamination tests were placed in sealed vials. The 

temperature and RH of the laboratory hood in which these 

vials were placed was typically about 24°C and 40% RH.

Shown in Table 5-2, recovery of GB, GD, and VX from 

100% bleach (6% ClO-) and 3000 ppm ClO2 was tested, as 

was recovery from neutralized solutions that were created 

via addition of STS to the bleach or ClO2 solutions. No 

CWAs spiked directly into bleach were recovered after 1 h. 

Likewise, little GB (1%) and no VX were recovered from 

neutralized bleach after 15 sec. This testing was inconclusive 

as to whether chemical degradation or inefficient recoveries 

account for the loss of recoverable CWA. In contrast, a 

relatively high recovery of GD from neutralized bleach 

solution with no detectable recovery of GD after 1 h in 

bleach indicates that bleach was effective against GD.

GB (8% of spike) and GD (58% of spike) were recovered 1 

h after being spiked directly into 3000 ppm ClO2 solution. 

Within the margin of error, the same amounts of GB (8%) 

and GD (56%) were recovered from neutralized ClO2

solution. This testing indicated that the ClO2 solution was not 

efficacious against GB or GD. VX was not recovered from 

neutralized ClO2 solution at 15 sec or from ClO2 solution 

after 1 h. The efficacy of ClO2 solution against VX could not 

be determined from these results.

For testing the two liquid decontamination technologies 

against CWAs on coupons, a slightly different control 

approach was used for each. When testing with liquid bleach, 

the positive control coupons (without decontamination) were 

not placed in any liquid solution — they were maintained in a 

vial exposed to air. When testing with liquid ClO2, the control 

condition (without decontamination) consisted of immersion 

of coupons in slightly acidic water. The test coupons and 

associated controls of the liquid decontamination tests 

were placed in sealed vials. The temperature and RH of 

the laboratory hood in which these vials were placed was 

typically about 24°C and 40% RH.

The results of the testing, shown in Table 5-1, suggest that 

liquid bleach may be a very effective decontamination agent, 

as none of the CWAs were detected on the coupons after a 

20 min soak in the bleach. However, the test was not without 

confounding parameters. The solution tests, shown in Table 

5-2 in which the CWA was directly spiked into bleach and 

neutralized bleach showed that both GB and VX were not 

detected in extracts of neutralized bleach, either because of 

rapid hydrolysis or poor extraction efficiency from aqueous 

solution into hexane. Thus the low measured recovery of 

these CWAs from the decontaminated coupons may be due in 

part to hydrolysis, volatilization, and/or partition of the CWA 

into the aqueous bleach and poor extraction efficiency into 

hexane. The low recovery of GD in bleach, combined with 

the fact that nearly 50% was extracted from a neutralized 

bleach solution, suggested that the bleach itself was effective 

in decontaminating GD on the materials tested. 

The long-term stability and integrity of building materials 

after exposure to fumigant ClO2

 indicated that the coupons 

were relatively unchanged after three months, and the carpet 

showed some minor “bleaching” after six months. 

Table 5-2. Mean Recovery of CWAs Directly Spiked into Liquid 

Decontamination Solutions 

Solution - Hold Time Before SRS 

Addition and Hexane Extraction

Mean CWA Recovery, 

% ± SD (n = 3)

GB GD VX

Bleach - 1 h ND, <0.1 ND, <0.1 ND, <0.7

Neutralized bleach - 15 sec 1 ± 0 41 ± 10 ND, <0.7

ClO2 - 1 h 8 ± 2 58 ± 5 ND, <0.7

Neutralized ClO2 - 15 sec 8 ± 1 56 ± 10 ND, <0.7

Recoveries calculated using Eq (1); mean and SD of recoveries shown here

ND = not detected
39

6.0

References

1. Persistence of Toxic Industrial Chemicals and Chemical Warfare Agents on Building Materials 

Under Conventional Environmental Conditions; (EPA/600/R-08/075); July 2008.

http://www.epa.gov/nhsrc/pubs/600r08075.pdf

2. Method 8000 “Determinative Chromatographic Separations” as part of SW-846 Third edition.

3.Battelle, Quality Management Plan (QMP) for the Technology Testing and Evaluation Program 

(TTEP); Version 2. January 2006.

4.Battelle, Test/QA Plan for the Systematic Evaluation of Technologies for Decontaminating 

Surfaces Inoculated with Highly Hazardous Chemicals (Chemical Warfare Agents and TICs), 

Manipulation of Environmental Conditions to Alter Persistence, Version 1. June 2005.
40

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41

7.0

Appendix A

The recoveries of DMMP and malathion on carpet, ceiling 

tile, and laminate, normalized to recoveries at Time 0 (0 h), 

both with and without fumigant ClO2 decontamination, are 

listed in Table A-1. Note that the statistical model that uses 

these data incorporates all data from an experiment into one 

model; in modeling that data, the averages at each time point 

change slightly to fit the single model. Thus averages listed 

in this table do not match precisely the averages listed in 

Table 4-4.

The recoveries of GB, TGD, and VX on carpet, laminate and 

ductwork, normalized to recoveries at Time 0 (0 h), both with 

and without fumigant ClO2 decontamination, are listed in 

Table A-2 (on page 42).

Note that the statistical model that uses these data 

incorporates all data from an experiment; in modeling that 

data, the averages at each time point change slightly to fit 

one model. Thus averages listed in this table do not match 

precisely the averages listed in Table 4-12. 

The recoveries of VX on carpet, laminate and ductwork, 

normalized to recoveries at Time 0 (0 h), with liquid ClO2

decontamination, are listed in Table A-2 (on page 42). 

Note that the statistical model that uses these data 

incorporates all data from an experiment; in modeling that 

data, the averages at each time point change slightly to fit 

one model. Thus averages listed in this table do not match 

precisely the averages listed in Table 4-19.

Table A-1. Normalized Mean Recovery of TICs on Building Materials 

over Time With and Without Sabre ClO2 Fumigant Decontamination

TIC Material Time (n) Normalized Mean Recovery, % ± SDa

Without Decon With Decon

DMMP

Carpet

1 h (n = 5) 33 ± 2 43 ± 6

3 h (n = 5) 24 ± 3 28 ± 6

7 h (n = 5) 16 ± 3 23 ± 4

Ceiling tile

1 h (n = 5) 39 ± 4 30 ± 2

3 h (n = 5) 28 ± 1 15 ± 1

7 h (n = 5) 12 ± 1 8.7 ± 0.3

Malathion

Carpet

1 h (n = 5) 89 ± 2 76 ± 3

3 h (n = 5) 90 ± 3 51 ± 5

7 h (n = 5) 87 ± 1 24 ± 2

Laminate

1 h (n = 5) 100 ± 12 28 ± 19

3 h (n = 5) 91 ± 5 3.3 ± 1.6

7 h (n = 5) 94 ± 10 0.4 ± 0.2

a) Calculated using Eq (7)
42

Table A-2. Normalized Mean Recovery of CWAs on Building 

Materials over Time With and Without Sabre ClO2 Fumigant 

Decontamination

CWA Material Time Normalized Mean Recovery, % ± SDb

Without Decon With Decon

GB Carpet

1 h 5.9 ± 1.1 4.1 ± 2.1

4 h 5.7 ± 0.2 3.3 ± 1.0

TGD

Carpet

1 h 77 ± 17 29 ± 5.2

2 h 57 ± 6.1 36 ± 17

Laminate

1 h 1.5 ± 1.6 6.1 ± 6.9

2 h 1.3 ± 1.6 0.10 ± 0.11

Ductwork

1 h 21 ± 7.5 14 ± 11

2 h 5.9 ± 2.6 7.4 ± 9.0

VX

Carpet

1 h 105 ± 31 0.35 ± 0.00a

4 h 97 ± 10 0.35 ± 0.00

Laminate

1 h 86 ± 8.0 0.35 ± 0.00

4 h 94 ± 5.5 0.35 ± 0.00

Ductwork

1 h 101 ± 3.1 0.35 ± 0.00

4 h 101 ± 9 0.35 ± 0.00

a) VX not detected in sample; value reported here is half the MDL

b) Calculated using Eq (7)

Table A-3. Normalized Mean Recovery of VX on Building 

Materials With and Without Liquid ClO2 Decontamination

CWA Material Time Normalized Mean Recovery, % ± SDa

Without Decon With Decon

VX

Carpet

10 min 5.8 ± 1.5 ND, <0.7

20 min 2.2 ± 0.5 ND, <0.7

30 min 3.2 ± 0.6 ND, <0.7

Laminate

10 min 1.9 ± 0.2 ND, <0.7

20 min 2.5 ± 1.2 ND, <0.7

30 min 1.8 ± 0.3 ND, <0.7

Ductwork

10 min 0.4 ± 0.2 ND, <0.7

20 min ND, <0.07 ND, <0.7

30 min ND, <0.07 ND, <0.7

a) Calculated using Eq (7)
43

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