United States

Environmental Protection

Agency

Office of Solid Waste and

Emergency Response

(5102G)

EPA-542-R-99-003

May 1999

www.epa.gov

clu-in.org

Innovations in Site

Characterization

Case Study: Dexsil L2000

PCB/Chloride Analyzer for Drum

Surfaces

EPA-542-R-99-003

May 1999

Innovations in Site Characterization

Case Study: Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

U.S. Environmental Protection Agency

Office of Solid Waste and Emergency Response

Technology Innovation Office

Washington, D.C. 20460
ii

Notice

This material has been funded wholly by the United States Environmental Protection Agency under

Contract Number 68-W7-0051. Mention of trade names or commercial products does not constitute

endorsement or recommendation for use.

Copies of this report are available free of charge from the National Service Center for Environmental

Publications (NSCEP), PO Box 42419, Cincinnati, Ohio 45242-2419; telephone (800) 490-9198 or (513)

489-8190 (voice) or (513) 489-8695 (facsimile). Refer to document EPA-542-R-99-003, Innovations in

Site Characterization- Case Study: Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces. This

document can also be obtained through EPA’s Clean Up Information (CLU-IN) System on the World

Wide Web at http://clu-in.org or by modem at (301) 589-8366. For assistance, call (301) 589-8368.

Comments or questions about this report may be directed to the United States Environmental Protection

Agency, Technology Innovation Office (5102G), 401 M Street, SW, Washington, D.C. 20460; telephone

(703) 603-9910.
iii

Foreword

This case study is one of a series designed to provide cost and performance information for innovative

tools that support less costly and more representative site characterization. These case studies will

include reports on new technologies as well as novel applications of familiar tools or processes. They are

prepared to offer operational experience and to further disseminate information about ways to improve

the efficiency of data collection at hazardous waste sites. The ultimate goal is enhancing the costeffectiveness and defensibility of decisions regarding the disposition of hazardous waste sites.
iv

Acknowledgments

This document was prepared for the United States Environmental Protection Agency’s (EPA)

Technology Innovation Office. Special acknowledgment is given to EPA Region 4 and the staff of Oak

Ridge National Laboratory for their thoughtful suggestions and support in preparing this case study.

Acknowledgment is also given to the Office of Emergency and Remedial Response and the Waste Policy

Institute for their review and suggestions.
v

Table of Contents

Notice ....................................................................... ii

Foreword .................................................................... iii

Acknowledgments ............................................................. iv

Case Study Abstract ............................................................ vii

Technology Quick Reference Sheet ................................................. ix

EXECUTIVE SUMMARY ........................................................ 1

PROJECT INFORMATION ...................................................... 3

Identifying Information ..................................................... 3

Background ............................................................. 3

Project Logistics/Contacts ................................................... 4

MEDIA AND CONTAMINANTS .................................................. 5

Matrix Identification ....................................................... 5

Project Geology/Stratigraphy ................................................. 5

Contaminant Characterization ................................................ 5

Matrix Characteristics Affecting Characterization Cost or Performance .................. 5

PROJECT CHARACTERIZATION PROCESS ........................................ 5

Goal of Characterization .................................................... 5

Sampling Workplan ........................................................ 7

Quality Assurance/Quality Control Measures .................................... 16

CHARACTERIZATION TECHNOLOGIES ......................................... 21

Wipe Sampling .......................................................... 21

Sampling Results and Cleaning Process Performance .............................. 23

Performance of Analytical Technology ......................................... 24

COST COMPARISON ......................................................... 29

OBSERVATIONS AND LESSONS LEARNED ...................................... 31

REFERENCES ............................................................... 32
vi

List of Figures

Figure 1: Process Control Chart for Free Release ....................................... 11

Figure 2: Process Control Chart for Metal Recycling ..................................... 11

List of Tables

Table 1. Analytical Data Quality Indicators (DQIs), Measurement Quality Objectives (MQOs), and

Corrective Actions for Dexsil field method ...................................... 18

Table 2. Performance characteristics of the Dexsil L2000 PCB/Chloride analyzer based on the

EPA/DOE ETV study and DOE criteria for selecting a field method to monitor the drum clean-up

process. ............................................................... 22

Table 3. Residual PCB levels in processed drums measured using the Dexsil L2000 PCB/chloride

analyzer and EPA SW-846 Method 8082. ....................................... 23

Table 4. Field analytical results of quality control samples. ................................ 25

Table 5. Comparison of costs for a sampling program using the Dexsil PCB field method and EPA

Method 8082. ........................................................... 29

List of Boxes

Box 1: Process Optimization Decision Tree ............................................ 8

Box 2: Process Evaluation Decision Tree .............................................. 8

Box 3: Production Phase Decision Tree .............................................. 12

Box 4: Hypothetical Random Sampling Protocol ........................................ 14
Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

vii

Case Study Abstract

Dexsil L2000 PCB/Chloride Analyzer for Sampling Drum Surfaces

East Tennessee Technology Park, Oak Ridge, Tennessee

Project Name and Location:

East Tennessee Technology Park

Oak Ridge, Anderson County, TN

37831

Sampling and Analytical

Technologies:

1. Wipe sampling

2. Dexsil L2000 PCB/Chloride

Analyzer

CERCLIS #

Not applicable

Period of Project Operation:

1940 to current

Operable Unit:

Not applicable

Current Project Activities:

Environmental and waste management

support for the Department of Energy

including operation of an incinerator for

wastes regulated by the Toxic Substances

and Control Act (TSCA).

Point of Contact:

David M. Carden

U.S. Department of Energy

P.O. Box 2001

Oak Ridge, TN 37831

423-576-9262

cardendm@oro.doe.gov

Media and Contaminants:

Metal drum surfaces contaminated

with oily waste and soil residues from

drum contents which had consisted of

various polychlorinated biphenyls

(PCB) waste materials.

Technology Demonstrator:

Department of Energy, 

Oak Ridge Operations

Oak Ridge, TN 37831

Number of samples analyzed during investigation:

26 wipe samples (Note: The original intent of PCB analyses was to monitor the clean-up of 7,000 empty drums, requiring

400 wipe samples. However, the clean-up work was aborted when the clean-up technology was found to be ineffective

during the initial phase of the work during which 26 wipe samples were analyzed.)

Project Cost Savings:

Analytical per sample costs (not including instrument cost or rental) for the Dexsil method is $12.50 compared to $50.00 for

the GC/ECD laboratory method. Had the project not been aborted, use of the analytical method would have resulted in more

than $10,000 in analytical cost savings.

Results:

A field method for PCB analysis provided rapid feedback regarding the effectiveness of a process for removing PCB surficial

contamination from empty drums. Rapid turnaround in field analyses resulted in the data user’s ability to abort the clean-up

work before expending additional resources on a drum clean-up process that was not working.
Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

viii

Description:

This case study describes how a field analytical method was used to measure PCB surficial contamination in empty drums

that were cleaned by a new process. The Department of Energy (DOE) Oak Ridge Operations had obtained approval from

the Environmental Protection Agency (EPA)-Region 4 to demonstrate the cleanup of 7,000 empty TSCA-regulated drums

using a new pelletized-CO2 scouring technique. DOE proposed and EPA approved a sampling program to determine the

effectiveness of the clean-up technology and evaluate compliance with EPA’s regulatory limits for releasing TSCA-regulated

items. The proposed sampling program consisted of (1) statistical control limits for process monitoring, (2) random sampling

of processed drums, (3) wipe sampling of container surfaces, and (4) rapid analysis of the wipe samples by a field method. 

During the trial period, the clean-up technology vendor attempted to clean about 20 of the most highly contaminated drums. 

Field analyses of residual PCB contamination, which provided results within one hour of wipe sample collection, showed that

the clean-up technology was not working as expected. On the basis of the field results, which were later confirmed when the

results of gas chromatography analyses became available, DOE aborted the drum clean-up project and the sampling program

was terminated.
ix

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x

TECHNOLOGY QUICK REFERENCE SHEET

Case Study Name: Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

Technology: Dexsil L2000 PCB/Chloride Analyzer

Summary of Case Study’s Performance Information

Project Role: 

Used to measure residual surface PCB

contamination in drums cleaned by a

new process.

Cost/Performance Information:

Analytical per sample cost (not including instrument cost or rental) for the Dexsil method is $12.50 per

sample compared to ~$50.00 for the GC/ECD laboratory method. If the drum cleaning project proceeded

as planned, use of the analytical method to verify regulatory compliance would have resulted in more than

$10,000 in analytical cost savings. 

Total Cost: Information not available

Project Cost Breakdown

Instrument Cost:

$3500

Consumables Cost:

Test kit reagents, $12.50 per

sample

Labor Cost:

Information not available

Waste Disposal Cost: Information

not available

Site-Specific Performance Observed:

Blanks analysis results ranged from 0.6 to 3.1 ug/100 cm2. Recoveries on Arochlor 1260 10 ug/100 cm2 standards (reported as Arochlor 1242) were

greater than 100% (range: 118-263%). Although the Dexsil field results were qualitatively consistent with the lab verification analyses, the latter

values tended to be higher than corresponding field measurements. Oily residues on the wipe samples may have exacerbated differences in extraction

efficiencies between the field and laboratory methods, each of which used different solvents and extraction times.

General Commercial Information (Information valid as of August 1998)

Vendor Contact:

John Siliman

Technical Support

Vendor Information:

Dexsil Corporation

One Hamden Park Drive

Hamden, CT 06517

203-288-3509

Limitations on Performance:

Cannot distinguish PCB congeners; identification of Aroclor not possible.

Availability/Rates:

Instrument and test kits (reagents

+ extraction vessels) can be

purchased from Dexsil

Principle of Operation: Metallic sodium strips PCB molecules of

chlorine; chloride levels are measured by a chloride-ion-specific

electrode and converted to PCB concentration using known chlorine

percentages present in Aroclors.

Power Requirements:

120 V

General Performance Information

Rate of Throughput: 5 samples per hour when sample preparation

and analyses were done outdoors; 10 samples per hour when sample

preparation and analyses were done indoors (from ETV study)

Known or Potential Interferences:

Other chlorinated organics that are preferentially soluble in a non-polar

solvent; iodine and bromine

Applicable Media/Matrices:

Soil, surface wipes, dielectric

fluids and oils

Analytes Measurable with

Commonly Achieved Detection

Limit Ranges:

PCBs, 2 ppm or 2 ug/100cm2 (if a 1000

cm2 area is wipe sampled).

Other General Accuracy/Precision Information:

(from ETV report EPA/600/R-98/109; see website

www.epa.gov/etv/library.htm#verifications) 

Average recovery in soil samples: 208%

Average recovery in extract samples: 149%

Precision in soil samples as relative standard deviation (RSD): 23%

Precision in simulated extract samples as RSD: 14%
Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

xi

Wastes Generated Requiring

Special Disposal: All materials

and reagents that contact PCBcontaminated material may be

considered TSCA waste;

applicable regulations for TSCA

waste disposal should be checked

before disposal of used materials

and reagents. 
xii

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Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

1

EXECUTIVE SUMMARY

This case study describes a field analytical method that was used to measure PCB surficial contamination

in empty drums to be cleaned by a new process. Approximately 7,000 empty 55-gallon drums that previously

contained PCB-contaminated material had accumulated at the Department of Energy (DOE)’s East

Tennessee Technology Park in Oak Ridge, TN. Because disposal of these drums following regulatorapproved methods would have been very costly, DOE requested permission from the Environmental

Protection Agency (EPA)-Region 4 to demonstrate the cleanup of these drums using a new CO2 scouring

technology. DOE also proposed and EPA approved a sampling program to demonstrate the effectiveness

of the clean-up technology and evaluate compliance with EPA’s regulatory limits for releasing PCBcontaminated items. The proposed sampling program consisted of (1) statistical control limits for process

monitoring, (2) random sampling of processed drums, (3) wipe sampling of container surfaces, and (4) rapid

analysis of the wipe samples by a field method. 

While taking advantage of the cost effectiveness and quick turnaround of field methods, DOE minimized the

risk of violating regulatory limits by selecting the field method based on the following criteria: (1) if field

results are biased, they must be biased high, (2) the field technique should provide a low probability of false

negative results, (3) the detection limit should be well below the lowest action/decision level, and (4) the field

technique should provide quantitative results rather than results in the form of ranges or intervals. Of the six

field methods evaluated during the Environmental Technology Verification (ETV) project co-sponsored by

EPA and DOE, only the Dexsil L2000 PCB/Chloride Analyzer satisfied these criteria and was thus selected

for monitoring the drum cleaning process. 

During the initial phase of the project, the CO2 scouring technology vendor attempted to clean 20 of the most

highly contaminated drums. The Dexsil PCB Analyzer was used to monitor residual PCB contamination in

the processed drums during this trial period. Field analyses, completed and reported within one hour of sample

collection, showed that the clean-up technology was not working as expected. On the basis of the fieldgenerated results, which were confirmed by wipe samples sent to an off-site laboratory for gas

chromatography analysis, DOE decided to abort the drum clean-up project before additional resources were

expended. Although only a limited data set was obtained to evaluate the overall performance of the Dexsil

field method, this case study demonstrates the usefulness of field methods for rapid decision-making.
2

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Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

3

PROJECT INFORMATION

Identifying Information

Demonstration Project for Pelletized CO2 Drum Cleaning Process

East Tennessee Technology Park

Oak Ridge, Anderson County, TN 37831

Background [1, 2]

Project Use: The East Tennessee Technology Park (ETTP), formerly the K-25 project, was

built in the 1940s as the Oak Ridge Gaseous Diffusion Plant, a facility where highly enriched

uranium was produced for the U.S. Army’s Manhattan Project. Since then, facility ownership

has been transferred to the U.S. Department of Energy (DOE), and its mission has evolved to

support environmental management activities within DOE’s Oak Ridge Operations (ORO). 

Specific activities currently being conducted at ETTP include the operation of a Toxic Substances

Control Act (TSCA) incinerator, which receives TSCA-regulated waste for disposal from DOE

facilities, and technical support for waste management within the DOE/ORO complex. ETTP is

currently managed by Bechtel Jacobs Company, LLC for DOE.

Release Investigation/History: As of early 1998, approximately 7,000 empty drums that

previously contained materials contaminated with polychlorinated biphenyls (PCBs) were stored

at ETTP. At one time the drums contained TSCA-regulated waste generated within the DOE

complex that were either repackaged or disposed of in the ETTP’s TSCA incinerator. Drum

contents ranged from transformer oils to contaminated soils with PCB levels exceeding 50 ppm. 

Records regarding the contaminant characteristics of the previous contents exist for most of these

drums, however residual PCB surficial contamination in these drums had not yet been

characterized. 

Regulatory Context: Under TSCA rules, the handling and disposal of empty drums that

previously contained PCB-contaminated material depends on the level of PCBs that were in the

drums. If the contents exceed 500 ppm of PCBs, the empty drum must be disposed of in an

incinerator that complies with 40 CFR 761.70, or in a chemical waste landfill that complies with

40 CFR 761.75. Alternatively, the drum can be triple-rinsed according to the standard procedures

in 40 CFR 761.79.

Some of the 7,000 empty drums at ETTP contained wastes that exceeded 500 ppm. Because

disposal of these drums in an incinerator or chemical waste landfill would be very costly, and

decontamination by triple-rinsing would generate a large volume of TSCA waste [2], DOE

requested approval from EPA Region 4 to demonstrate an innovative scouring technology by

which pelletized CO2 is utilized to remove surficial contamination from the drums. Pursuant to the

Oak Ridge Reservation PCB Federal Facility Compliance Agreement (FFCA) between EPA and

DOE, containers cleaned using a process other than triple-rinsing must be tested for residual PCB
PROJECT INFORMATION, CONT’D.

Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

4

contamination before disposal. PCB surface levels must not exceed 10 μg/100 cm2 if the cleaned

drum is to be free-released, or 100 μg/100 cm2 if the drum is to undergo metal recycling. Vendor

claims regarding the CO2 scouring technology led DOE to believe that drums cleaned by this

process would show residual PCB levels acceptable for free-release. Furthermore, the waste

generated by this clean-up technology and the overall clean-up cost per drum would be an order

of magnitude less than that associated with triple-rinsing.

Because the pelletized CO2 clean-up process was not an EPA-approved technique, DOE

proposed implementing a testing program to ensure that EPA’s established surface cleanup

standards would be met. The testing program was designed to include (1) statistical control limits

for process monitoring, (2) statistical random sampling of processed drums, (3) wipe sampling of

container surfaces, and (4) rapid analysis of the wipe samples by an on-site measurement

method. Through a memorandum issued to DOE [2], EPA Region 4 approved the demonstration

of the CO2 cleaning technology, and concurred with the testing program DOE had proposed with

minor modifications. Within the context of the Oak Ridge Reservation PCB Federal Facility

Compliance Agreement, flexibility is accorded to the Region in applying PCB regulations to

DOE’s particular problems with managing PCB/radioactive waste streams.

Project Logistics/Contacts

Federal Lead Agency: U.S. Department

of Energy, Oak Ridge Operations

Federal Oversight Agency:

Environmental Protection Agency, Region 4

DOE Program Manager:

David M. Carden

U.S. Department of Energy

P.O. Box 2001

Oak Ridge, TN 37831

423-576-9262

cardendm@doe.oro.gov

Project Engineer:

Steve E. Foster 

Bechtel Jacobs Company, LLC

P.O. Box 4699 MS7234

Oak Ridge, TN 37831-7234

423-574-8032

fosterse@bechteljacobs.org

Technical Consultant for DOE:

Chip Davis

SMS Inc.

55 Jefferson Circle

Oak Ridge, TN 37830

423-576-0250

Analytical Chemist:

N. Katy Huffaker

Bechtel Jacobs Company LLC

P.O. Box 4699 MS7169

Oak Ridge, TN 37831-7169

423-576-9186

huffakernk@bechteljacobs.org

Regulatory Agency Contact:

Craig Brown

U.S. Environmental Protection Agency,

Region 4

Atlanta Federal Center

61 Forsyth Street, SW

Atlanta, GA 30303-8909
PROJECT INFORMATION, CONT’D.

Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

5

404-562-8990
Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

6

MEDIA AND CONTAMINANTS

Matrix Identification

Type of matrix sampled and analyzed: Drum surfaces of 55-gallon drums

Project Geology/Stratigraphy

This information is not relevant to this project.

Contaminant Characterization 

Primary contaminant groups: Polychlorinated biphenyls (PCBs)

Matrix Characteristics Affecting Characterization Cost or Performance

PCB surface contamination in the processed drums was characterized by wipe sampling using

gauze pads saturated by a solvent (see detailed description under Characterization Technologies). 

The presumption is that all the PCB contaminants on the sampled surface are effectively

collected by the gauze pad. However, if a significant oily residue is present, the gauze pad can

become saturated and cannot absorb all the oil present on the sampled surface. Under such

conditions, the measured surface contamination can be negatively biased. These effects would

apply for both the field and laboratory analyses of the wipe samples. According to personnel

involved with the project, oily residues were observed in some of the drums even after they had

been processed. Thus, the analytical results for the highly contaminated drums may

underestimate the actual levels of residual surface contamination. 

Oily residue on the wipe samples could also exacerbate differences in extraction efficiency

between the field and laboratory methods. This is discussed in more detail under the Section on

Performance Evaluation.

PROJECT CHARACTERIZATION PROCESS

Goal of Characterization

DOE obtained approval from EPA to demonstrate an innovative CO2 scouring technology to

remove surficial contamination from 7,000 empty TSCA drums that were in storage at ETTP. 

Because this new technology had not been approved by EPA as a substitute for the standard

triple-rinsing procedure outlined in 40 CFR 761.79, monitoring of the clean-up process was

required to certify its effectiveness. DOE and EPA agreed on a sampling and analysis plan [2]

which would establish with a known level of confidence that the clean-up process was meeting

regulatory goals, i.e., that residual PCB surface levels were below 10 μg/100 cm2 if the cleaned

drums were to be free-released, or below 100 μg/100 cm2 if the cleaned drums were to be
Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

7

subjected to metal smelting. Using the Data Quality Objectives Process to organize the goals and

expectations of this project produces the following outputs:

1. State the Problem: This problem can be stated in two parts:

C Demonstrate a cheaper, effective drum cleanup method.

C Use a cheaper, rapid turn-around analytical method to sample and analyze a

representative number of the drums to ensure cleanup goals are met.

2. State the Project Decision(s): 

C Determine whether the new cleaning process can achieve one of two preferred drum

disposal options by meeting applicable regulatory levels: free-release (10 μg/100 cm2)

and/or metal recycling (100 μg/100 cm2). 

C Designate each 500-drum batch as appropriate for one or the other disposal option.

3. Define the appropriate data inputs:

• PCB concentrations (as μg/100 cm2) in any residues remaining on the inside surfaces of

drums after cleaning.

4. Define the conditions under which to collect data and other study boundaries: 

C Wipe samples will be taken from the drum’s inside surfaces, and analyzed by a method

which can provide the required PCB data. 

C The number of drums from each 500-drum batch that will be sampled will be determined

according to a statistically-designed sampling plan. 

C The collection and analysis of samples will use a field analytical method with a defensible

quality assurance plan. 

5. State the Decision Rule(s): 

C Decision Rule for using the new cleaning process: If the process is unable to clean drums

to either the free-release or metal recycling regulatory criteria, then the new process

cannot be used.

C Decision Rule for the free-release disposal option: If the nominal action level of 10 μg/100

cm2 of total PCBs cannot be achieved, the free-release option cannot be used to dispose

of drums.

C Decision Rule for the metal recycling disposal option: If the nominal action level of 100

μg/100 cm2 cannot be achieved, the metal recycling option cannot be used to dispose of

drums.

6. Specify limits on decision errors: For each batch of 500 drums, under a worst case-scenario,

there must be 95% confidence that no more than 10% of the drums in the batch exceed the

nominal action level and a 95% confidence that no more than 10% false negative analytical

results are produced by the analytical method. It was expected that, with the safety factors built

into the statistical and analytical design, actual exceedances would be much less. After generation

of the statistical data for each batch of drums, the actual probability of exceeding the nominal
Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

8

action level will be determined from the analytical data sets, and the statistical confidence actually

achieved will be documented in the project report.

[The reader is cautioned that depending on the regulatory context, the use of a sampling

and analysis plan that permits any statistical exceedance of TSCA regulatory limits for

PCBs might not be acceptable to the regulating entity. Under the Oak Ridge Reservation

PCB Federal Facility Compliance Agreement, flexibility in setting statistical limits on

decision errors was permitted by Region 4 for this project evaluating an innovative drum

cleanup method.]

7. Optimize the Design:

C Optimization of the sampling and analysis plan will be carried out according to detailed

quality control and corrective action measures. With the exception of the use of periodic

field duplicates as described in the analytical QA/QC plan, a single sample will be taken

to characterize each drum, as long as the following assumption is demonstrated to be

valid: Any PCBs remaining after drum cleaning are uniformly distributed on the inner

surfaces of the drums.

Since it was discovered during the initial evaluation of the cleaning process that it could not

achieve even the 100 μg/100cm2 regulatory limit, it could be said the project was “optimized” by

aborting it so that no more resources than necessary were expended on an unworkable project.

The analytical Data Quality Objective (DQO) Summary Statement for this project is “Verify with

at least 95% confidence that no more that 10% of 7,000 drums remain contaminated at applicable

regulatory levels after being cleaned with the new process.”

Sampling Workplan

Monitoring of the drum clean-up process was divided into an initial intensive sampling phase for

process optimization followed by a production sampling phase for process control and

effectiveness verification. A discussion of each sampling phase is provided below, and follows

the decision tree graphics presented in Boxes 1 and 2, below.

Process Optimization: Initial Intensive Sampling (See Box 1)

The objectives of this phase were (1) to determine whether the CO2 process can achieve at least

one of the regulatory goals (100 μg/100 cm2 for metal recycling, or 10 μg/100 cm2 for free

release), and (2) to obtain process control information that will be used to monitor the clean-up

process during the subsequent production phase. 
Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

9

Legend

SD= Dexsil Sample Results in ug/100cm 2

SL = Laboratory Sample Results in ug/100cm 2

Process Fully Effective for

Laboratory Analysis Free Release

EPA Method 8082

Process Not Effective

Clean a 50-drum Batch Test All Drums

Dexsil Only

All S D < 5

and 95% UCL D <

10?

All S L < 10

10 < All S L < 100

Batch Fully

Compliant for

Metal Recycling

No

Yes

No

Production Phase: Process

Verification Control Chart for

Free Release using S D

Yes

Reoptimize Process

Calculate Average and

Standard Deviation using S D

Yes

No

Resample Noncompliant

Drums

Production Phase: Process

Verification Control Chart for

Metal Recycling using S D

Calculate Average and

Standard Deviation using S D

Box 2: Process Evaluation Decision Tree

Legend

SD= Dexsil Sample Results in ug/100cm2

SL = Laboratory Sample Results in ug/100cm 2

Clean a 25-drum Batch

Test All Drums

Dexsil and

EPA Method 8082

Move to

Process Evaluation Phase

Optimize Cleaning

Procedure

SD < 10

SL < 10

Is this the second

round of

processing?

No

Abort Project

Yes

No

Yes

Box 1: Process Optimization Decision Tree
Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

10

For this initial phase, 75 of the most contaminated drums were selected based on visual inspection

and records of prior contents. The clean-up technology vendor was permitted to process 25 of

the 75 drums in order to determine the optimum amount of CO2 scouring time needed to remove

surficial contamination to acceptable levels (see Box 1). Residual contamination during this

optimization stage was measured by taking wipe samples from the inner surfaces of the

processed drums, and analyzing the wipes using the Dexsil PCB test kit. Duplicate samplings of

10 drums were sent to the laboratory for confirmatory analysis by gas chromatography. Wipe

sampling and the Dexsil PCB test kit are described in more detail in the Characterization

Technologies section, below.

Unfortunately, it quickly became clear that neither regulatory goal could be achieved. The

demonstration was discontinued because the process was deemed “ineffective” before the next

step of the process optimization and evaluation plan was reached. For the educational purposes of

this case study, however, further discussion of the project plan will continue in order to explain the

rationale of this study.

After optimization, the vendor was to process the remaining 50 drums using the optimized

conditions to demonstrate process effectiveness to DOE and EPA (see Box 2). The surfaces of

those 50 processed drums would then be wiped, and the sample results used to determine

whether or not the process can achieve the regulatory goal of 10 μg/100 cm2 for free-release of

the drums, or 100 μg/100 cm2 for metal smelting of the drums. The decision rules are as follows:

Acceptance Criteria for Process Effectiveness

(1) If the residual surficial contamination as measured by the Dexsil PCB test is less than 5

μg/100 cm2 for all 50 drums, then the process is deemed “fully effective for free

release.” There is an additional requirement in the workplan that “the upper 95%

confidence level on the mean of the 50 consecutively processed drums must be less than

the regulatory cleaning goals.” Depending on the variability present in the 50 sample

results, it is possible to have an upper 95% confidence level that is greater than the

regulatory cleaning goal, even though each of the 50 samples is less than the regulatory

cleaning goal. If the mean of the data were significantly less than the regulatory

cleaning goal, then this outcome might not occur. But if the mean of the data is close to

the regulatory goal with enough (expected) variability in the data, there is a good chance

that the upper 95% confidence level would exceed the regulatory limit.

(2) If one or more drums has residual levels above 5 μg/100 cm2

 as determined by the field

test, those drums will be re-sampled and the wipes will be sent to a fixed laboratory for

analysis by EPA Method 8082 (Polychlorinated Biphenyls (PCBs) by Capillary Column

Gas Chromatography) [8]. If the fixed lab analysis results are less than 10 μg/100 cm2

for all samples, then the re-sampled drums are considered acceptable and the process

deemed “fully effective for free release.” If the fixed lab analysis results are greater

than 10 μg/100 cm2 but less than 100 μg/100 cm2 for all samples, then the process is

deemed “fully effective for metal recycling.” If at least one of the fixed lab results is
Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

11

greater than 100 μg/100 cm2, then the process is deemed “ineffective” and the clean-up

vendor may be asked to re-optimize the process and demonstrate technology

effectiveness using another set of 50 drums. 

The original project design was directed at meeting the free release regulatory standard

of 10 μg/100 cm2. However, if the cleanup process was unable to meet that stringent

standard, the same design, with minimal modifications, could be used to meet the standard

for metal recycling of 100 μg/100 cm2. For example, 50 and 100 μg/100 cm2 could

replace 5 and 10 μg/100 cm2 as the field-specific and nominal regulatory action levels,

respectively.

The decision trees above (Boxes 1 and 2) establish the role and usefulness of the Dexsil kit as a

screening tool to select samples that require testing by Method 8082 to confirm regulatory

compliance during these initial phases of work which were designed to establish process

effectiveness. If the cleaning contractor had been able to satisfy the “full process effectiveness”

criteria for at least one of the two goals and had successfully processed a batch of 50 drums

according to the decision tree above, the mean and standard deviation (SD) of residual surface

contamination in these 50 drums, as determined by results of the Dexsil PCB test kit, would be

used as parameters for process control during the production phase. This is accomplished by the

development of a control chart. An example of a control chart is provided in Figure 1 using a

fictitious data set that might have resembled the data generated during the 50-drum processeffectiveness evaluation, had the cleaning process proven “fully effective for free release.”

Figure 2 shows a control chart that may have been created had the cleaning technology failed the

free-release goal, but was demonstrated “fully effective for metal recycling.” The Mean, Process

Warning Limit, and Process Control Limit for a control chart would be derived from the data

generated during the 50-drum Process Evaluation Procedure, during which the cleaning process

would be maximally optimized. Later, during the production phase of work, data collected from

each of 28 randomly selected drums from each 500-drum batch would be plotted on the chart as

a means of assessing whether the cleaning process continued to perform optimally as all 7,000

drums were cleaned (described in more detail below).
Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

12

Figure 1: Process Control Chart for Free Release

Figure 2: Process Control Chart for Metal Recycling
Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

13

Batch Compliant for

Free Release

Laboratory Analysis

EPA Method 8082

Process Not Effective

Clean a 500-drum

Batch

Test Sample

Drums

Dexsil Only

All SD < 5

All SL < 10

10 < All SL < 100 Batch Compliant for

Metal Recycling

No

Yes

No

Reoptimize Process

Plot Dexsil Data on

Control Chart: Free

Release

No

Resample Noncompliant

Drums

Select Random

Sample of 28 Drums

Yes

Plot Dexsil Data on

Control Chart: Metal

Recycling

Reoptimize

Cleaning Process

More than 3 S D> 2 SD or

More than 1 S D > 3 SD or

7 consecutive SD > Mean

Yes

No Process within Control Limits

Legend

SD= Dexsil Sample Results in ug/100cm 2

SL = Laboratory Sample Results in ug/100cm 2

Box 3: Production Phase Decision Tree

Process Verification and Control: Production Phase Sampling

Had the process been deemed “fully effective” either for free release or metal recycling,

production phase sampling would be conducted with random verification sampling to ensure that

the process remains in control and that process action limits, established during the Process

Evaluation Procedure and used to prepare the Process Control Chart, are not exceeded (see Box

3). 
Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

14

 The drums will be processed in batches of 500, and 28 drums per batch will be randomly selected

for wipe sampling and analysis using Dexsil PCB test kits, and the results plotted on a Control

Chart (28 sample results plotted on each chart, with one chart plotted per batch of 500 drums).

A discussion of two easily implemented protocols for random sampling of these drums appears in

Box 4. The number of samples per batch was determined based on the statistical design

proposed for this project, which was a nonparametric one-sided tolerance limit that does not

require a presumption about the normality of the distribution of the measurements [4]. Using a

sample size of 28 randomly selected drums allows one to state with 95% confidence that no more

than 10% of a 500-drum batch will have residual levels greater than the highest result in the set of

28 random samples. Stated another way, the statistical design assures that there is less than a 5%

chance that more than 50 drums out of a 500-drum batch will have a surficial PCB concentration

greater than the highest result within the set of 28 randomly selected samples. It is possible with

this statistical test to select more stringent tolerance limits, for example, instead of using the

criteria that no more than 10% of a 500-drum batch would have residual levels greater than the

highest result at the 95% confidence level, it is possible to specify that only 1% of a 500-drum

batch (or only 5 drums) would have levels greater than the highest result at the 95% confidence

level. Choosing this tolerance limit would raise the required number of randomly selected drums

to be sampled to about 298, rather than 28, substantially increasing the cost and effort involved. 

Because of all the other conservatively stringent controls in place for this sampling plan, EPA

Region 4 was comfortable permitting a less rigorous confidence level for this aspect of the

sampling design. The reader should also recall from previous discussions that this type of

statistical sampling design may not be acceptable to regulators under other PCB cleanup or

decontamination scenarios.

Note that the data from the 28 randomly sampled drums from each 500-drum batch serve at least

two, and possibly three, distinct purposes: 

1) Use of the data (specifically, using the highest result of the 28-sample data set) in determining

compliance with the nonparametric one-sided tolerance limit statistic used to predict residual

levels of PCBs in the 500-drum batch after cleaning [4] and ensure meeting the defined Decision

Error Limit (see the Acceptance Criteria for Processed Drums, p. 13); 

2) Plotting the 28 data points on control charts to permit close monitoring of the efficiency of the

cleaning process so that re-optimization of the CO2 scouring process can be performed at the

first indication of a loss of efficiency (see Process Control, below); and

3) The possible use of the data to calculate parametric or nonparametric statistical parameters, as

appropriate (such as a confidence limit on the 99th percentile for a “not-to-exceed” regulatory

standard) [8].

The decision tree in Box 3 assumes that the initial testing had demonstrated that the process
Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

15

could achieve the regulatory limit for free release, but routing batches of drums to the metal

recycling option is possible if some batches did not meet the criteria for free-release, but did meet

the less stringent recycling criteria.

The statistical procedure for selecting the number of drums that would be sampled in each batch for the one-sided nonparametric tolerance limit is as follows: [7]

n = log(alpha)/log(P) = log(0.05)/log(.90)

n = -1.3010/-0.0458 = 28

Where:

alpha = 1 - level of confidence desired; and

P = the percent of compliant drums.

A 500-drum batch is assembled (from the total of about 7,000 drums) in an area in preparation for the cleaning process.

A random number generator is used to select 28 numbers between 1 and 500. (For example, say that 34 and 79 are two

of the random numbers selected.) Before any drums are cleaned, the selected 28 random numbers are ordered on a list,

from lowest to highest in numerical order. Then the cleaning process is begun. As each drum is about to be subjected to

the cleaning process, it is assigned the next consecutive number (from 1 to 500). When the 34th drum is cleaned, it is

immediately sampled before being stacked with the rest of the cleaned drums. When the 79th is cleaned, it is sampled

before being stacked, and so on.

For example: 

Order of Sampling 1 2 3 4 5 ... 25 26 27 28

Order of Drum

Cleaning & Drum ID

Number

34 79 101 128 188 ... 305 420 452 463

Alternatively, all 500 drums could be numbered as they are assembled in preparation for cleaning. After all have been

assigned numbers, use a random number generator to select the numbers of the 28 drums to be sampled, and record those

numbers in the order in which they were chosen. Cleaning does not have to proceed in any particular order. When a

drum is cleaned which was previously selected for the set of 28, it is sampled before being stacked with the rest of the

cleaned drums. The order of cleaning of these numbered drums must be preserved, but the numbers themselves do not

have to be in order. 

For example: 

Order of Sampling

(after cleaning)

1 2 3 4 5 ... 25 26 27 28

Drum ID Number 305 251 301 34 101 ... 452 292 197 79

Box 4: Hypothetical Random Sampling Protocol
Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

16

Acceptance Criteria for Processed Drums

(1) If all 28 randomly-selected drums have residual contamination less than 5 μg/100 cm2

using the Dexsil test kits, the batch of 500 drums are deemed clean enough for free

release. Since the nonparametric statistical procedure used ensures that no more than

10% of the 500 drums in a batch would exceed the highest result in the data set, and

since the highest result is less than 5 μg/100 cm2, such a data set meets the defined

statistical goal given in Step 6 of the DQO Process that no more than 10% of the batch

exceed the regulatory limit of 10 μg/100 cm2 .

(2) If one or more of the 28 drums has residual contamination greater than 5 μg/100 cm2

using the Dexsil test kits, these drums will be re-sampled and the wipes analyzed using

EPA Method 8082. If all of the fixed lab analysis results are less than 10 μg/100 cm2,

then the 500 drums are deemed clean enough for free release. If at least one of the fixed

lab analysis results is greater than 10 μg/100 cm2 but less than 100 μg/100 cm2, then the

500 drums are deemed acceptable for metal recycling. If at least one of the fixed lab

analysis results is greater than 100 μg/100 cm2, then the drums are deemed unacceptable

for free release or recycling and the vendor may be required to re-process all 500 drums

until random sampling demonstrates that one of the regulatory limits has been achieved. 

Process Control

After the data from the 28 random samples are evaluated using the applicable decision tree, and

the corresponding 500-drum batch is deemed “clean,” the data from the 28 random samples will

be used to indicate whether process effectiveness is beginning to degrade. This is done by

plotting the data on a control chart. Each batch of 500 drums would have its 28 samples plotted on

a copy of the control chart generated during Process Evaluation, and the cleaning order must be

preserved when plotting the data on the chart. Deterioration of cleaning effectiveness would be

apparent if the results of any of the 28 random samples began to rise above the limits established

on control charts during process optimization. Even if those results were not yet exceeding the

regulatory limit, it would be a signal that the cleaning process might again need to be optimized,

and early corrective action could be implemented. The following criteria would have been used

as indicators of diminishing process effectiveness.

1. Three or more of the 28 samples exceeds0 + 2 SD (i.e., the Process Warning Limit),

where 0 and SD are the mean and standard deviation respectively of the residual levels

in the 50 drums used to initially demonstrate “full effectiveness” and prepare control

charts.

2. At least one of the 28 samples exceeds 0 + 3 SD (i.e., the Process Control Limit).

3. If any seven consecutive data points have residual levels greater than 0.
Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

17

On-Going Process Control Validation

The random sampling scheme used for process verification does not guarantee that none of the

500 drums will exceed the regulatory limits. However, the sampling scheme does ensure with a

95% confidence level that the maximum number of drums that can violate the regulatory limit in a

batch of 500 drums is 50, under a worst case scenario. It is possible that data from the 28

random samples in a batch might be used to project the probability that an individual drum within

that batch would exceed a regulatory limit. As the project proceeds, the data from each round of

28 random samples is added to the data collected during previous rounds. The mean and standard

deviations of these data are calculated, and the results compared with the process control limits

for the project. If the comparison shows a significant difference between the calculated mean or

standard deviations and the process control assumptions, this will serve as a warning that the

early assumptions about the variability of the concentrations in the drums to be cleaned may not

be valid.
Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

18

CHARACTERIZATION TECHNOLOGIES

Wipe Sampling

Residual PCB contamination in the processed drums is tested by wipe sampling, a standard EPA

technique for sampling contamination on smooth surfaces [5]. Wipe sampling is accomplished by

applying 2 mL of chromatographic-grade hexane to a sterile gauze pad, then using the soaked

gauze pad to wipe a pre-determined, pre-measured area (1000 cm2 or 12.5-in x 12.5-in) on the

surface of a drum. Pre-measured aliquots of hexane were provided by Dexsil in sealed glass

ampules to prevent contamination from external sources prior to use. After sampling, the hexane

was allowed to evaporate, and the wipe was then extracted and analyzed following procedures

for the Dexsil PCB test method (see below). 

As noted in the section on quality control measures below, a significant component of

measurement variability in wipe samples can be from heterogeneous analyte distribution of the

surface being sampled. This must be considered when establishing QC criteria for replicate

measurements and comparisons between different analytical methods (e.g., field vs lab) using

separately collected wipe samples.

As discussed elsewhere in this case study, a number of factors can complicate wipe sampling

(such as the amount and character of the sampled residue) and compromise analytical integrity. 

If complicating factors are anticipated during project planning, modifications to the wipe sampling

procedure can be evaluated to ensure the representativeness and comparability of the analytical

testing.

PCB Analysis Using the Dexsil L2000 PCB/Chloride Analyzer

The Dexsil L2000 PCB/Chloride Analyzer is a field-portable instrument designed to quantify PCB

concentration in soils, dielectric fluids, and surface wipes. For wipe samples, PCBs are extracted

from the wiped sample by solvating the wipe with 10 mL of isooctane for 30 seconds. Inorganic

chloride and water are removed from the isooctane extract by passing it through a Florisil

cartridge, then the extract is mixed with a reaction solution and metallic sodium (which

dechlorinates the PCB molecules). The free chloride released into the reaction solution is

measured with an ion-specific electrode. Only chloride which was part of any organic molecule

contributes to the signal (the Dexsil PCB kit is not specific for PCBs); inorganic chloride originally

present in the sample does not interfere. The output of the chloride-specific electrode is

electronically converted to the surficial PCB contamination (in μg/100 cm2) of a 1000 cm2 wipe

sample area. The free chloride concentration is converted to a Arochlor concentration based on

the analyst’s choice of one of four different settings—Aroclor 1242, Aroclor 1260, Askarel A

(60% Aroclor 1260/40% trichlorobenzene), and total chloride. The instrument does not report

Aroclor 1254. Aroclor identification can not be made because the measurement technique can

not distinguish among the PCB congeners. Hence, the user needs to use site history or previous

data to set the analyzer to convert the chloride concentration to the appropriate PCB congener. 

Alternatively, the user can set the analyzer to report results as Aroclor 1242, which has the
CHARACTERIZATION TECHNOLOGIES, CONT’D.

Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

19

lowest percentage of chlorine, to obtain the most conservative (highest) PCB sample

concentrations.

Quality Assurance/Quality Control Measures

The key to an effective QA/QC plan is that it take into consideration the limitations and strengths

of the sampling and analytical methods involved, and the goals of the project. To meet the goals

set forth in the preceding section, the Dexsil kit must be shown to produce data which meet the

needs of site-specific decision process. One of the most important needs is that the site-specific

results are consistently comparable (or consistently and predictably conservative) as compared to

the ‘reference methods’ by which the TSCA action levels were derived. Had the drum cleaning

method worked, that is, had the pelletized CO2 process been able to physically remove the oily,

often viscous, residue coating the inside surfaces of many of the drums, demonstrating

comparability between the wipe sample results obtained by the Dexsil kit and those obtained by a

traditional laboratory may have been a simple matter. 

Unfortunately, since the cleaning process was ineffective at removing the oily residue, wipe

sampling and analysis became a difficult task for a number of reasons which are discussed in

more detail later in this section. If good comparability between laboratory and field

measurements at all analyte concentrations is to expected to provide data defensibility, 

representative sampling and analysis issues must be addressed, or this aspect of the quality

assurance plan will fail.

Since it was not expected that the drum cleanup method would leave so much oily material, the

sampling and analytical difficulties encountered were not anticipated. Compliance with all aspects

of the QA/QC plan (as it was designed) could not be demonstrated in the limited data set

generated. However, since the first goal of the project was to establish whether or not the

innovative drum cleanup method could work, and since both the physical and analytical evidence

was overwhelming that it did not, compliance with the QA/QC plan was not relevant to the

decision to abort the pelletized CO2 demonstration project due to a lack of effectiveness. 

A defensible QA plan requires refinement of analytical and sampling procedures to cope with

matrix issues if the data are to be expected to support complex decision-making. This is best done

by a pilot study which establishes the optimum sample selection, collection, extraction, cleanup,

analysis and interpretation procedures to address site-specific conditions and decision goals. It

should be kept in mind that some studies have found variability due to sampling factors to routinely

be 3 or more times as large as variability stemming from the analytical method [9]. The

uncertainty stemming from variability in sample selection and collection needs to be quantified or

estimated to avoid undue efforts to eliminate insignificant analytical uncertainty, while the

sampling uncertainty remains substantial and unaddressed.
CHARACTERIZATION TECHNOLOGIES, CONT’D.

Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

20

Measurement Quality Objectives (MQOs)

Measurement Quality Objectives are the QC requirements an analytical method must be able to

achieve to meet the goals of the project as expressed in the Data Quality Objectives. In selecting

a field technique for monitoring the drum cleanup process, DOE set criteria (the MQOs) to

reduce the risk of violating regulatory limits. These criteria were: (1) if field results are biased,

these must be biased high (i.e., expected recoveries relative to the “true values” must be greater

than or equal to 100%), (2) the field technique should provide a rate of false negatives at less than

10% at a 95% confidence limit, (3) the detection limit should be well below 5 μg/100 cm2, and (4)

the field technique should provide quantitative results in μg/100 cm2 (as opposed to results in the

form of a concentration range or interval). Of the 6 field methods evaluated during the

Environmental Technology Verification (ETV) project co-sponsored by EPA and DOE [3], only

the Dexsil test kit satisfied these criteria and was thus selected for monitoring the drum cleaning

process. 

Analytical Data Quality Control

Quality control (QC) measures specified for the Dexsil field method are summarized in Table 1. 

The laboratory utilized the QC measures discussed in EPA Method 8082.

The performance data collected during the ETV evaluation of the Dexsil PCB test kit [3] and the

data needs of the project were used to establish realistic expectations for the precision criteria in

Table 1. It was recognized that measurement variability can be attributed to the following: (1)

analytical variability, as affected by operator proficiency and consistency, and by potential

variability in extraction efficiency which depends on the nature of the materials collected by the

wipe sample, and (2) spatial variability or a heterogeneous distribution of the analyte across the

inside surfaces of the drum. Analytical variability due to operator proficiency and consistency is

monitored through the use of control charts on the blank and standard results. In the ETV study,

replicate analyses of standards and well-mixed soils by the Dexsil field method showed relative

standard deviations (RSDs) of 14% and 23%, respectively [3]. These RSDs, which correspond

to relative percent differences (RPDs) of 19% and 33% (RPD = 2RSD), were obtained under

near-ideal conditions of sample-to-sample homogeneity. The choice of the precision limit follows

from the discussion below setting the accuracy MQO.

The lower accuracy limit (9.5 for the 10 μg/100 cm2 standard) was selected such that this value

would be rounded to the corresponding standard value. This corresponds to a lower recovery

limits of 95%, and ensures that field analytical results will not be biased low due to the

determinative step itself. The upper accuracy limits were derived from the recovery values

determined during the ETV demonstration [3]: the recovery for 10 ppm standards (equivalent to

the 10 μg/100 cm2 regulatory limit for the free-release scenario) was 207%, while the recovery

for 100 ppm standards was 91%. (Note that these recoveries were achieved in the absence of

other sources of variability in sample results, such as sampling heterogeneity or extraction
CHARACTERIZATION TECHNOLOGIES, CONT’D.

Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

21

inefficiencies.) A recovery of 207% for a 10 μg/100 cm2 standard is 20 μg/100 cm2, and thus is

equivalent to 100% RPD. Since under the free-release scenario outlined in Box 3, all results

greater than 5 μg/100 cm2 are sent to the laboratory for confirmation testing anyway, using an

initial RPD of 100% is reasonable. If sample heterogeneity and analytical performance permit

more stringent limits on duplicate precision, this will be determined during the preparation of an

analytical control chart (see Table 1). 

Table 1. Analytical Data Quality Indicators (DQIs), Measurement Quality Objectives

(MQOs), and Corrective Actions for Dexsil Field Method

Data Quality Indicator

(DQI) for Method

Measurement Quality Objective

(MQO)

Corrective Actions (if control limits

are exceeded)

Blanks: A field blank,

consisting of an unused wipe

or gauze pad soaked with 2

mL of chromatographic grade

hexane, will be analyzed by

the field method for every 20

field samples.

Blank results will not be greater

than the lowest action level (5.0

μg/100 cm2). Precision of blanks

will be less than 100% RSD. 

All blanks will produce a numerical

result, therefore a project-specific

MDL is recommended.

Permissible rate of false positive

results*: the MDL must be

determined before the rate of false

positives can be evaluated.

The development and use of an

analytical control chart for blanks is

recommended: after obtaining 20-30

blank results, the data is used to

calculate the mean and standard

deviation to prepare a control chart

to record subsequent blank results. 

If a blank result exceeds 5.0 μg/100 cm2 or

the 2 SD line of the control chart, a second

blank will be immediately run. If that

blank result is within the QC limits, the

method will be considered to be in control.

If the 2nd blank is also outside control

limits, troubleshooting 1 of the analyst and

equipment will be performed before other

drum wipe samples are analyzed.

Accuracy: A quality control

solution spiked at 10 μg/mL

(corresponds to 10 μg/100

cm2 regulatory limit for free

release) will be analyzed for

every 20 field samples. 

For a 10 μg/100 cm2 standard, the

result must be $9.5 and #30 μg/100

cm2. 

Permissible rate of false negative

results*: 0% (It is unacceptable for

the 10 μg/mL standard to produce a

result less than the MDL.)

The use of an analytical control

chart is recommended: after

obtaining 20-30 standard results, the

data is used to calculate the mean

and standard deviation to prepare a

control chart to record subsequent

standard results. 

If a standard result exceeds the criterion or

the 2 SD line of the control chart, a second

standard will be run immediately. If that

result is within the QC limits, the method

will be considered to be in control. If the

2nd standard result is also outside control

limits, troubleshooting 1 of the analyst and

equipment will be performed before other

drum wipe samples are analyzed.
CHARACTERIZATION TECHNOLOGIES, CONT’D.

Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

Table 1. Analytical Data Quality Indicators (DQIs), Measurement Quality Objectives

(MQOs), and Corrective Actions for Dexsil Field Method

Data Quality Indicator

(DQI) for Method

Measurement Quality Objective

(MQO)

Corrective Actions (if control limits

are exceeded)

22

Precision: A duplicate field

sample will be collected for

every 20 field samples.

Maximum acceptable relative

percent difference of 100% between

duplicates.

If the same drum is not resampled, the

next drum to be sampled will have

duplicate samples taken. If the criterion is

still exceeded, duplicate measurements of

blanks and the standard will be performed

to verify instrument performance. If

acceptable precision cannot be achieved

with the blanks and standards,

troubleshooting 1 of the analyst and

equipment will be performed before other

drum wipe samples are analyzed.

Table 1. Analytical Data Quality Indicators (DQIs), Measurement Quality Objectives

(MQOs), and Corrective Actions for Dexsil Field Method (continued).

Data Quality Indicator

(DQI) for Method

Measurement Quality Objective

(MQO)

Corrective Actions (if control limits

are exceeded)

Laboratory verification of

field analyses/Comparability: 

During the initial and

production phase of

sampling, 10% and 5%

respectively of all field test

kit results will be verified by

EPA SW-846 Method 8082. 

Under a free-release decision

tree, all Dexsil results >5 will

be verified.

Field results will be compared to lab

results to ensure conservatism; that

is, most field results must be equal

to or higher than laboratory results.

If field results are trending lower

than lab results, a the project

statistician will be consulted to

determine whether trend is

significant (that is, the integrity of

the decision-making process is in

question). Corrective action will be

implemented if the statistician

believes it is necessary.

If other QC measures are acceptable, a

re-evaluation of the extraction step of the

field procedure will be undertaken to

identify correctable extraction

inefficiencies for this project-specific

matrix. If modification of the method

cannot ensure conservative results, yet the

bias appears to be predictable and

relatively constant, consultation with a

statistician will determine if the field

method-specific action level may be

adjusted to restore the desired margin of

safety.
CHARACTERIZATION TECHNOLOGIES, CONT’D.

Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

Data Quality Indicator

(DQI) for Method

Measurement Quality Objective

(MQO)

Corrective Actions (if control limits

are exceeded)

23

1

 Troubleshooting of the analyst will involve an experienced chemist observing the analyst to verify that correct

procedures are being followed during sample collection, extraction, and analysis. Tiered troubleshooting of the

equipment should be performed by an experienced chemist and will involve any of the following depending on the

nature of the problem: (1) evaluate sources of contamination: open a new box or lot of wipe pads, open a new lot of

hexane or extraction solvent, (2) evaluate blank or standard integrity: prepare fresh blank or standard solutions with

new solvent, (3) evaluate reagent/kit integrity: open a new Dexsil test kit box or lot, assess the condition and

performance of the chloride-specific electrode, (4) resumption of drum sampling will not resume until acceptable

performance of the field method is obtained.

* A false negative result is one where the analyte is not detected above the reporting limit when it is actually

present above the reporting limit. A false positive result is one where the analyte is detected above the reporting

limit when it is not actually present.

One other factor needs to be considered when setting the initial upper limit on the 10 μg/100 cm2

standard: the standard used in this project is Aroclor 1260, yet the Dexsil instrument was set to

report its readings as Aroclor 1242, which will additionally bias the results high. So a reasonable

starting value for the upper limit on the field QC standard is 30 μg/100 cm2. This value can be

adjusted during the project if warranted by the applicable analytical control chart. Just as the

process control charts monitor possible drifting of performance that signals the need for reoptimization of process parameters, so too, the use of analytical control charts continually monitor

the analytical method for instrument drift or other causes of deteriorating analytical performance.

The laboratory method selected for verifying the field analyses was SW-846 Method 8082,

Polychlorinated Biphenyls (PCBs) by Capillary Column Gas Chromatography (GC/ECD). The

wipe samples for lab analysis were immediately immersed in 10 mL of hexane and transported to

the fixed laboratory where aliquots of the hexane extracts were injected into the GC/ECD for

PCB quantification. Thus, the laboratory and field methods were different in the following

aspects: (1) extraction solvent (hexane vs isooctane), (2) length of time for extraction solvent

exposure, and (3) determinative technique (GC/ECD vs. ion-specific electrode). 

An extensive evaluation of several PCB field technologies was performed under the ETV

program co-sponsored by EPA and DOE. Table 2 lists the performance characteristics obtained

from the ETV evaluation of the Dexsil PCB kit [3], and illustrates that the Dexsil PCB kit met the

criteria set by DOE for selecting a field method to monitor the drum clean-up process.

Table 2. Performance characteristics of the Dexsil L2000 PCB/Chloride analyzer based

on the EPA/DOE ETV study [3] and DOE criteria for selecting a field method to monitor

the drum clean-up process [2].
CHARACTERIZATION TECHNOLOGIES, CONT’D.

Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

24

Performance

Characteristics

ETV Study Result DOE Selection Criterion

Accuracy Average recovery in soil samples was 208%. Average

recovery in simulated extract samples (correspond

best to wipe samples) was 149%.

If the field method is biased, it

must be biased high (i.e.,

recoveries must be $100%).

Detection Errors PCBs were detected above the generic MDL for four

out of eight blank samples; there were no false

negative results.

There must be a low probability

of false negatives using the field

method.

Detection limits The method detection limit (MDL) following the EPA

definition was 7.1 ppm. After compensation for bias,

the resulting MDL agreed with Dexsil’s specified

MDL of 2 ppm. The latter is numerically equivalent

to 2 μg/100 cm2 of a 1,000 cm2 sample wipe area

extracted with 10 mL of isooctane.

The detection limit must be less

than the lowest action level. The

project-specific MDL may be

defined by a pilot study to

address matrix effects.

Measurement range Manufacturer-specified measurement range is between

2 and 2,000 ppm. Quantitative results were

determined for extract samples with levels of 10 and

100 ppm.

The field method should provide

quantitative results around the

critical values selected for the

project.

Precision The overall precision based on relative standard

deviations (RSDs) was 23% for soil samples and 14%

for extract samples. 

None specified

Cost Equipment purchase: $3,500;

$5 to $16 per sample (matrix dependent)

None specified
Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

25

PERFORMANCE EVALUATION

Sampling Results and Cleaning Process Performance

Over a period of four days, the drum-cleaning technology vendor was permitted to treat 20 to 25

drums to optimize the cleaning process. During this trial period, the Dexsil PCB test kit was used

to monitor residual PCB surface levels in the processed drums. Some of the drums were recleaned and re-sampled several times for a total of 27 field samples. The field testing provided

immediate feedback regarding the effectiveness of the cleaning process, and showed that the

process was unable to consistently and reliably achieve the action limit of 5 μg/100 cm2 (see

Table 3,[6]). Even reproducibly achieving an action limit of 50 μg/100 cm2 (appropriate for the

metal smelting goal) proved difficult, with several drums exceeding 2,000 μg/100 cm2 of residual

contamination. During the first day of the trial period, five out of six drums had residual levels

greater than 200 μg/100 cm2. Corresponding laboratory measurements later confirmed the field

test results (see Table 3). On the fourth and last day of the trial period, six out of eight drums had

residual levels measured by the Dexsil test kit as exceeding 200 μg/100 cm2, with some levels

exceeding 2,000 μg/100 cm2. These field results were also confirmed by laboratory analysis (see

Table 3). At this point, DOE aborted the project before additional resources were expended on a

drum cleaning process that was clearly not working. The production phase of the sampling

workplan described previously was never implemented.

Table 3. Residual PCB levels in processed drums measured using the Dexsil L2000

PCB/chloride analyzer and EPA SW-846 Method 8082 [6].

Sample ID Dexsil Test Method1 Method 8082

μg/100 cm2 as Aroclor 1242 μg/100 cm2 Aroclor2

July 7, 1998

1 4.8 11 1254

2 >200 5,397 1254

3 >200 2,123 1254

4 >200 1,169 1254

5 >200 1,857 1254

6 >200 1,810 1254

July 8, 1998

1 6.3 NP

2 3.9 NP

3 3.8 NP

4 4.8 NP
PERFORMANCE EVALUATION, CONT’D.

Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

Table 3. Residual PCB levels in processed drums measured using the Dexsil L2000

PCB/chloride analyzer and EPA SW-846 Method 8082 [6].

Sample ID Dexsil Test Method1 Method 8082

26

1 7.8 NP

Table 3. Residual PCB levels in processed drums measured using the Dexsil L2000

PCB/chloride analyzer and EPA SW-846 Method 8082 [6] (continued).

Sample ID Dexsil Test Method1 Method 8082

μg/100 cm2 as Aroclor 1242 μg/100 cm2 Aroclor2

July 9, 1998

2 >100 NP

3 14.1 NP

4 22.0 NP

6 4.0 NP

7 3.9 NP

8 82.7 NP

9 3.8 NP

July 15, 1998

1 >200 NP

2 >200 NP

3 >200 NP

4 >2,000 17,749 1254

5 >1,000 NP

6 3.2 5 1260

7 9.8 26.3 1254

8 >1,000 19,098 1260

1Although the Dexsil analyzer is capable of reporting quantitative results up to 2,000 μg/100 cm2

, field results during

this phase of the project were reported quantitatively only if the levels were below 100 μg/100 cm2. Over 100 μg/100

cm2, the results were reported variously as “>100", “>200", “>1,000" or “>2,000". 

2

 Aroclor identified in sample based on relative amounts of PCB congeners detected.

NP = Not Performed (No sample sent for laboratory confirmation.)
PERFORMANCE EVALUATION, CONT’D.

Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

27

Performance of Analytical Technology

The performance of the Dexsil test kit can only be evaluated based on the limited data set that

was collected before the clean-up project was aborted [6]. Table 4 shows the results of the field

blanks and of the 10 μg/100 cm2 standards used as QC samples. The field blank results are

comparable to those measured during the ETV evaluation of the Dexsil test kit [3] where the

average PCB level measured in unspiked simulated extract samples (analogous to field blanks)

was 2.3 ppm.

Table 4. Field analytical results of quality control samples [6].

Quality Control Sample Field Method Result 

(μg/100 cm2 reported as 

Aroclor 1242)

Applicable MQO 

(from Table 1)

(μg/100 cm2)

Blanks

Analyzed on July 7, 1998 2.0 <5.0

Analyzed on July 8, 1998 0.6 <5.0

Analyzed on July 9, 1998 3.1 <5.0

Analyzed on July 9, 1998 1.0 <5.0

Analyzed on July 13, 1998 2.3 <5.0

Analyzed on July 14, 1998 3.7 <5.0

Analyzed on July 15, 1998 2.4 <5.0

Summary of Blank Performance

 

Mean (0) = 2.5; SD = 1.0

Precision (RSD): 40%

Establish Control Chart

RSD#100%

10 μg/100 cm2 Arochlor 1260

Standard

Analyzed July 7, 1998 26.3 $9.5 and #30

Analyzed July 8, 1998 11.8 $9.5 and #30

Analyzed July 9, 1998 21.0 $9.5 and #30

Analyzed July 13, 1998 23.8 $9.5 and #30

Analyzed July 14, 1998 24.1 $9.5 and #30

Analyzed July 15, 1998 12.6 $9.5 and #30

Summary of Standard Performance Mean (0) = 19.9; SD = 6.2

Accuracy (as % recovery): 199%

Precision (RSD): 31%

Establish Control Chart

RSD#100%

In this study, the mean was 2.5 ppm, and the precision for the blank readings was 40%. Analysis
PERFORMANCE EVALUATION, CONT’D.

Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

28

of the QC standard samples showed that false negatives at the regulatory control limit of 10

μg/100 cm2 are unlikely. All recoveries for the 10 μg/100 cm2 standard samples were greater

than 100%. The high recoveries are consistent with the ETV study [3] which showed that the

Dexsil test results were biased high in both soil and simulated extract samples. High recoveries in

this study are also expected because Aroclor 1260 was used for the QC standard, yet the Dexsil

kit was set to report the result as Aroclor 1242. The precision of the Dexsil kit for the 10 μg/100

cm2 QC standard was 31%. The precision of neither the Dexsil test kit nor the laboratory method

with respect to the actual samples could be evaluated from the data set because no field

duplicates were collected.
PERFORMANCE EVALUATION, CONT’D.

Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

29

The comparability MQO (laboratory verification analyses) was evaluated by comparing the field

results with the corresponding ten laboratory analyses. In general, the lab analyses were

consistent with the field method results when compared against the field action level of 5 μg/100

cm2 (see Table 3), although the desired MQO that the field results be at least as high, or higher,

than the lab results (to maintain conservative decision-making in the field) was not achieved in this

initial limited data set. Had this project continued, corrective action would have been performed

before implementing the applicable decision tree.

A previous evaluation of the Dexsil PCB test kit (the ETV study) showed that results strongly

tend to be biased high with average recoveries of 149% for simulated extract samples at

concentrations of 10 and 100 μg/100 cm2 [3]. This bias was evident in this project in that the 10

μg/100 cm2 standard had recoveries up to 260%, as discussed previously. However, the data set

in Table 3 suggests that the Dexsil results are biased low compared to the laboratory results. 

Further, even lower results would be expected had the Dexsil analyzer been set to report results

as Aroclor 1260 (the Aroclor occasionally reported by the laboratory method and closer in

chlorine content to Aroclor 1254, which was the Aroclor most reported by the laboratory), instead

of Aroclor 1242. Reporting of Dexsil results as Aroclor 1242 was chosen to add additional

conservatism to the field results. Therefore, it is surprising that the quantitative Dexsil results

underestimated the confirmatory laboratory results. One can speculate that this negative bias

may be due to a less efficient extraction of PCBs from the matrices collected on the wipe pads

using isooctane as compared to hexane, which was the solvent used for Method 8082. In the

ETV study, wipe sample extracts were simulated by the use of spiked solvent aliquots, and as a

consequence, the efficiency of isooctane for extracting PCBs collected on wipes/gauze pads was

not evaluated. Extraction efficiency differences may be further exacerbated if the wipes are

saturated with oily residues, i.e., hexane may be more effective at extracting PCBs from viscous

residues than isooctane. In addition to differences in solvent, the extraction times were also

drastically different between the field and laboratory methods. The wipes were extracted for

only 30 seconds using the Dexsil method, while the wipes for laboratory analyses were immersed

in hexane for a much longer time as they were transported to the fixed analytical laboratory.

Another potential reason for the bias may be reflected in the sequence in which the laboratory

and field wipe sample duplicates were collected. Since a 1,000 cm2 area was required for each

wipe-sampling, it was difficult to allocate accurately delineated non-overlapping sample areas for

the field and lab samples due to the size of the drums. If the laboratory wipe samples were

collected first and the field sample areas overlapped with the lab sample areas, it is possible that

the laboratory wipe samples would have demonstrated higher PCB levels.

Had the cleaning procedure proved effective and the project gone forward, any significant

negative bias between field and laboratory results would have been addressed by troubleshooting. 
Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

30

COST COMPARISON

Table 5 lists estimated costs for the testing program that DOE had planned for verifying the drum

cleanup process. The calculations in this table assume that approximately 400 wipe samples will

be analyzed (7,000 drums processed in 14 batches of 500 from which 28 are wipe sampled). For

400 wipe samples, at least 60 QA/QC samples (blanks, standards and replicates) would have

been required according to the sampling plan using the Dexsil test kit. It is assumed that the same

number of QA/QC samples would have been required if a laboratory method were used. The

sampling program using the field method also includes laboratory verification of 40 samples

(10%), assuming that with an effective cleaning program, few field analyses would have

exceeded the criteria of the decision tree requiring additional laboratory confirmation. Under

ideal circumstances, the total cost of the sampling program using the Dexsil kit (including the

purchase of the Dexsil analyzer) is less than 50% of a similar program using a laboratory method. 

Had this project been executed to completion, considerable savings would have resulted from the

use of the field method for clean-up verification with the added benefit of immediate turn-around

of results.

Although the sampling program was not completed, use of the Dexsil test kit during the vendor’s

trial period was clearly advantageous for DOE because rapid feedback was provided to the

clean-up technology vendor that the process was not working. The immediate availability of

analytical results also allowed DOE to rapidly reach a decision to abort the project, thereby

avoiding expending more resources and accumulating more liability to the vendor.

Table 5. Comparison of costs for a sampling program using the Dexsil PCB field

method and EPA Method 8082.

Cost Element Dexsil PCB Method EPA Method 8082

Equipment cost (capital) $3,500 $0

Analysis of samples $12.50 x 400 samples =

$5,000

$50 x 400 samples = $20,000

Analysis of QA/QC samples $12.50 x 60 samples = $750 $50 x 60 samples = $3,000

Analysis of laboratory

verification samples

$50 x 40 samples = $2,000 $0

TOTAL $11,250 $23,000
31

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OBSERVATIONS AND LESSONS LEARNED

Because the project was aborted during its initial phase and the full sampling program was never

implemented, this case study represents a very limited data set from which to draw observations

and lessons learned in using the Dexsil PCB field method. However, the case study does

illustrate that the use of a field method enabled rapid decision-making by the data users. The

benefits of the field PCB method are identified as follows [6]:

• blank QC samples showed no false negative analytical results (a false negative analytical

result is one where the analyte is not detected when it is actually present);

C reduced per sample costs ($12.50 per sample vs. approximately $50 per sample using

Method 8082); and

• rapid turn-around for results (within an hour of the last sample taken).

Use of the field method proved itself by immediately identifying to DOE that the process was not

working as expected. Therefore, the process was stopped before DOE had assumed a larger

liability [6].

Lesson learned concerning process control tools:

C Depending on how the first 50 samples used to prove process effectiveness are distributed,

0 + 2SD and 0 + 3SD could possibly be greater than the action limit. If this were true,

then the statistical control charts may be superfluous.

Lesson learned concerning the analytical QA/QC plan:

C Had the project gone forward, the value of a detailed, well-planned and documented quality

assurance plan would have been vital to detecting, correcting or compensating for any

matrix interferences or other problems related to non-representative sampling and analysis. 

(On the other hand, had the cleaning procedure worked, matrix problems would not have

existed, since the contaminated matrix would have been removed.) Detailed QA plans and

project-specific standard operating procedures (SOPs) are critical to implementing field

analytical methods to produce reliable data which supports defensible decision-making. 

Clearly defined MQOs and corrective measures ensure that field analytical data will be of

known and documented quality.

C If a project’s data defensibility depends partly on good comparability between laboratory

and field measurements, representative sampling and analysis issues must be addressed, or

the data will not be able to support project decision-making.

C Although much of the technical detail of rigorous QA plans may seem complex, designing

and implementing statistically valid analytical quality assurance plans is a routine matter for

experienced analytical chemists and statisticians. Tapping into appropriate expertise during

project planning, and then at critical junctures during execution, will substantially increase
Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

33

the likelihood that projects will successfully meet the goals of public safety and confidence. 
Dexsil L2000 PCB/Chloride Analyzer for Drum Surfaces

34

REFERENCES

1. East Tennessee Technology Park Overview - Mission - Vision - Environmental Management

and Enrichment Facilities Programs - History;

http://www.ornl.gov/K25/techdemo/ettpover.htm; posted May, 1997.

2. Letter from Winston A. Smith of EPA Region 4 to Suzanne P. Riddle of DOE dated April 20,

1998. Enclosure: Sampling and Analysis Plan Certification of Cleanliness for Empty TSCA

Drums, Revision 1, DOE Oak Ridge Operations, Environmental Management Technical

Services Team.

3. Dindal, A.B.; Bayne, C. K.; Jenkins, R. A.; Billets, S.; Koglin, E. N. Environmental

Technology Verification Report: Electrochemical Technique/Ion Specific Electrode,

Dexsil Corporation, L2000 PCB/Chloride Analyzer. Environmental Protection Agency,

EPA/600/R-98/109, August 1998.

4. Walpole, R.; Myers, R. H. Probability and Statistics for Engineers and Scientists. New

York: MacMillan Publishing Co., Inc., 1978.

5. U.S. Environmental Protection Agency Environmental Response Team, Standard Operation

Procedures #2011, Chip, Wipe and Sweep Sampling, Rev. 0.0. November 1994.

6. Memorandum from Chip Davis, PCB Field Screening Coordinator for DOE, to Brian

Demonia and David Carden, DOE Program Managers, October 23, 1998.

7. Gibbons, Robert D. Statistical Methods for Groundwater Monitoring. New York. John

Wiley & Sons, Inc., 1994.

8. U.S. Environmental Protection Agency, 1986 and updates, Test Methods for Evaluating

Solid Waste-Physical/Chemical Methods, EPA Publication SW-846, Chapter 9, Office of

Solid Waste, Washington, D.C.

9. Jenkins, T.F., et al. Assessment of Sampling Error Associated with Collection and

Analysis of Soil Samples at Explosives-Contaminated Sites. US Army Corps of Engineers

Cold Regions Research and Engineering Laboratory. Special Report 96-15. September 1996.