September 2005 

Environmental Technology 

Verification Report 

TELEDYNE-API 

MODEL 101E AMBIENT 

HYDROGEN SULFIDE ANALYZER 

Prepared by 

Battelle 

Under a cooperative agreement with 

U.S. Environmental Protection Agency 
September 2005 

Environmental Technology Verification

Report

ETV Advanced Monitoring Systems Center 

TELEDYNE-API

MODEL 101E AMBIENT

HYDROGEN SULFIDE ANALYZER

by

Ann Louise Sumner

Amy Dindal

Zachary Willenberg

Karen Riggs

Battelle

Columbus, Ohio

Richard Pfeiffer

Jerry Hatfield

United States Department of Agriculture

National Soil Tilth Laboratory

Ames, Iowa

and

Eric Winegar

Applied Measurement Science 

Fair Oaks, California
Notice 

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

Development, has financially supported and collaborated in the extramural program described 

here. This document has been peer reviewed by the Agency. Mention of trade names or 

commercial products does not constitute endorsement or recommendation by the EPA for use. 

ii 
Foreword 

The U.S. Environmental Protection Agency (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, the EPA’s Office of Research and Development 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. 

The Environmental Technology Verification (ETV) Program has been established by the EPA to 

verify the performance characteristics of innovative environmental technology across all media 

and to report this objective information to permitters, buyers, and users of the technology, thus 

substantially accelerating the entrance of new environmental technologies into the marketplace. 

Verification organizations oversee and report verification activities based on testing and quality 

assurance protocols developed with input from major stakeholders and customer groups 

associated with the technology area. ETV consists of six verification centers. Information about 

each of these centers can be found on the Internet at http://www.epa.gov/etv/. 

Effective verifications of monitoring technologies are needed to assess environmental quality 

and to supply cost and performance data to select the most appropriate technology for that 

assessment. Under a cooperative agreement, Battelle has received EPA funding to plan, 

coordinate, and conduct such verification tests for “Advanced Monitoring Systems for Air, 

Water, and Soil” and report the results to the community at large. Information concerning this 

specific environmental technology area can be found on the Internet at 

http://www.epa.gov/etv/centers/center1.html. 

iii 
Acknowledgments 

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

verification test, analyze the data, and prepare this report. We would like to thank 

Dr. Raul Dominguez, Jr., South Coast Air Quality Management District; Dr. D. Bruce Harris, 

EPA; and Dr. William Ollison, American Petroleum Institute, for their technical review of the 

test/quality assurance plan and for their careful review of this verification report. We also thank 

Dr. Gary Norris, EPA, for his review of the test/quality assurance plan and Dr. Alan Vette, EPA, 

for review of this report. We also would like to thank Mr. Kenwood Scoggin and 

Dr. Steven Trabue, U.S. Department of Agriculture (USDA), for their assistance in performing 

reference sample analysis and Mr. Timothy Hart, USDA, for providing meteorological data. We 

thank the American Petroleum Institute for providing funding to Applied Measurement Science 

for their participation in this verification test and the USDA Agricultural Research Service for 

providing logistical support. 

iv 
Contents 

Page 

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

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

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

List of Abbreviations ........................................................ viii

1 Background ............................................................... 1

2 Technology Description ...................................................... 2

3 Test Design and Procedures ................................................... 3

3.1 Introduction ........................................................ 3

3.2 Site Description ..................................................... 3

3.3 Test Design ........................................................ 4

3.3.1 Accuracy, Bias, Precision, and Linearity ............................ 7

3.3.2 Span and Zero Drift ............................................ 7

3.3.3 Response Time ............................................... 8

3.3.4 Interference Effects ............................................ 8

3.3.5 Comparability ................................................ 8

3.3.6 Data Completeness ........................................... 11

3.3.7 Operational Factors ........................................... 11

4 Quality Assurance/Quality Control ............................................ 12

4.1 Reference Method Quality Control Results ............................... 12

4.1.1 Time-Integrated Reference Method Quality Control Results ............ 12

4.1.2 In Situ Reference Method Quality Control Results .................... 13

4.2 Audits ........................................................... 14

4.2.1 Performance Evaluation Audits .................................. 14

4.2.2 Technical Systems Audits ...................................... 14

4.2.3 Audit of Data Quality ......................................... 15

4.3 Quality Assurance/Quality Control Reporting ............................. 15

4.4 Data Review ...................................................... 15

5 Statistical Methods and Reported Parameters .................................... 17

5.1 Accuracy ......................................................... 17

5.2 Bias ............................................................. 17

5.3 Precision ......................................................... 18

5.4 Linearity ......................................................... 18

5.5 Span and Zero Drift ................................................. 18

5.6 Response Time .................................................... 18

5.7 Interference Effects ................................................. 19

v 
5.8 Comparability ..................................................... 19

5.9 Data Completeness ................................................. 20

6 Test Results .............................................................. 21

6.1 Accuracy ......................................................... 23

6.2 Bias ............................................................. 26

6.3 Precision ......................................................... 26

6.4 Linearity ......................................................... 27

6.5 Span and Zero Drift ................................................. 27

6.6 Response Time .................................................... 31

6.7 Interference Effects ................................................. 32

6.8 Comparability ..................................................... 34

6.8.1 Time-Integrated Comparability .................................. 34

6.8.2 In Situ Comparability .......................................... 35

6.9 Data Completeness ................................................. 38

6.10 Operational Factors ................................................. 38

7 Performance Summary ..................................................... 40

8 References .............................................................. 43

Appendix A. Model 101E Checklist ............................................ A-1

Appendix B. Model 101E and Time-Integrated Comparability Data .................... B-1

Appendix C. Model 101E and In Situ Comparability Data ........................... C-1

Figures 

Figure 2-1. Teledyne-API Model 101E Ambient H2S Analyzer ......................... 2

Figure 3-1. Test Site .......................................................... 4

Figure 3-2. Swine Barn Interior ................................................. 4

Figure 3-3. Test Site Lagoons ................................................... 5

Figure 3-4. Teflon Manifold .................................................... 5

Figure 6-1. Meteorological Conditions and Model 101E Ambient H2S Measurements ....... 22

Figure 6-2. Hourly Averaged Model 101E H2S Measurements Plotted as a 

Function of Wind Direction .......................................... 23

vi 
Figure 6-3. Model 101E Accuracy Results ........................................ 24

Figure 6-4. Model 101E Linearity Results ........................................ 28

Figure 6-5. Span and Zero Drift Control Chart ..................................... 31

Figure 6-6. Model 101E Response Time Results ................................... 32

Figure 6-7. Comparison of Time-Integrated Reference Measurements with 

Averages from the Model 101E ....................................... 35

Figure 6-8. Scatter Plot of Model 101E Results versus Time-Integrated Reference 

Measurements .................................................... 36

Figure 6-9. Comparison of Selected In Situ Reference Measurements with 

Model 101E Averages and Measurement Data ............................ 37

Figure 6-10 Scatter Plot of Model 101E Results versus In Situ Reference Measurement . . . . . 37

Tables 

Table 3-1. Test Activities ..................................................... 6

Table 3-2. H2S Concentrations and Order for Multipoint Challenges .................... 7

Table 3-3. Interferants and Approximate Concentrations for Interference Checks ........... 9

Table 4-1. Reference Method Quality Control Requirements and 

Target Acceptance Criteria ........................................... 13

Table 4-2. Summary of Data Recording Process ................................... 16

Table 6-1. Accuracy Results .................................................. 25

Table 6-2. Calculated Precision of the Model 101E ................................. 26

Table 6-3. Span and Zero Baseline Response ..................................... 29

Table 6-4. Span and Zero Drift Check Results .................................... 30

Table 6-5. Response Time Determinations ....................................... 33

Table 6-6. Interference Effect Evaluation ........................................ 33

vii 
CCV 

List of Abbreviations 

AFO animal feeding operation 

AMS Advanced Monitoring Systems 

API Advanced Pollution Instrumentation 

ASTM American Society for Testing and Materials 

continuing calibration verification 

CI confidence interval 

EPA U.S. Environmental Protection Agency 

ETV Environmental Technology Verification 

GC gas chromatography 

H2S hydrogen sulfide 

i.d. internal diameter 

Lpm liter per minute 

m meter 

mm millimeter 

ln natural logarithm 

NIST National Institute of Standards and Technology 

PE performance evaluation 

PFPD pulsed flame photometric detection 

pg picogram 

ppb part per billion 

ppm part per million 

%D percent difference 

%R percent recovery 

PMT photomultiplier tube 

QA quality assurance 

QC quality control 

QCS quality control samples 

QMP quality management plan 

RSD relative standard deviation 

scc standard cubic centimeter 

sccm standard cubic centimeter per minute 

SD standard deviation 

SO2 sulfur dioxide 

TSA technical systems audit 

UHP ultra-high purity 

USDA U.S. Department of Agriculture 

UV ultraviolet 

viii 
Chapter 1 

Background

The U.S. Environmental Protection Agency (EPA) supports the Environmental Technology 

Verification (ETV) Program to facilitate the deployment of innovative environmental technologies through performance verification and dissemination of information. The goal of the 

ETV Program is to further environmental protection by accelerating the acceptance and use of 

improved and cost-effective technologies. ETV seeks to achieve this goal by providing highquality, peer-reviewed data on technology performance to those involved in the design, 

distribution, financing, permitting, purchase, and use of environmental technologies. 

ETV works in partnership with recognized testing organizations; with stakeholder groups 

consisting of buyers, vendor organizations, and permitters; and with the full participation of 

individual technology developers. The program evaluates the performance of innovative technologies by developing test plans that are responsive to the needs of stakeholders, conducting 

field or laboratory tests (as appropriate), collecting and analyzing data, and preparing peerreviewed reports. All evaluations are conducted in accordance with rigorous quality assurance 

(QA) protocols to ensure that data of known and adequate quality are generated and that the 

results are defensible. 

The EPA’s National Exposure Research Laboratory and its verification organization partner, 

Battelle, operate the Advanced Monitoring Systems (AMS) Center under ETV. The AMS 

Center, in collaboration with the U.S. Department of Agriculture’s (USDA’s) National Soil Tilth 

Laboratory and Applied Measurement Science, recently evaluated the performance of the 

Teledyne-Advanced Pollution Instrumentation (API) Model 101E ambient hydrogen sulfide 

(H2S) analyzer in quantifying H2S in ambient air at a swine finishing farm. 

1
Chapter 2 

Technology Description

The objective of the ETV AMS Center is to verify the performance characteristics of 

environmental monitoring technologies for air, water, and soil. This verification report provides 

results for the verification testing of the Model 101E. Following is a description of the Model 

101E, based on information provided by the vendor. The information provided below was not 

verified in this test. 

The Model 101E measures H2S concentrations in ambient air by thermal conversion of H2S to 

sulfur dioxide (SO2) with a molybdenum catalytic converter and ultraviolet (UV) fluorescence of 

the SO2 gas. The SO2 gas is excited using a zinc lamp, and the UV fluorescence is measured using 

a photomultiplier tube (PMT). The Model 101E lower detectable limit is 0.4 parts per billion 

(ppb). An optical shutter compensates for PMT drift, and a reference detector corrects for changes 

in UV lamp intensity. The Model 101E software provides automatic alarms if operational 

parameter diagnostic limits are exceeded. 

Data can be recorded in the internal data acquisition system or transmitted to a data logger or 

chart recorder using either an RS-232 interface or analog outputs. The built-in data acquisition 

system uses the Model 101E’s internal memory and permits logging multiple parameters, 

including averaged or instantaneous (greater than 1 hertz) concentration values; calibration data; 

and operating parameters such as flow rate, pressure, and lamp intensity. Data are logged as onesecond to one-hour averages, depending on the data acquisition settings. Stored data are retrieved 

through a serial or Ethernet port or from the front panel, allowing performance of predictive 

diagnostics and enhanced data analysis by tracking 

parameter trends. Data files are saved as commadelimited text and can be opened in Microsoft Excel 

or other program for analysis. The analog outputs 

can be configured to provide instantaneous or 

averaged H2S concentration readings and/or 

operating parameters. For this test, H2S 

concentrations and operating parameters were 

logged as one-minute averages and retrieved 

through the Ethernet port to a laptop computer 

running Teledyne-API’s APICOM software. 

Figure 2-1. Teledyne-API Model 101E 

Ambient H2S Analyzer 

The Model 101E weighs 20.5 kilograms (45 pounds); and it is 178 millimeters (mm, 7 inches) 

high, 432 mm (17 inches) wide, and 597 mm (23 inches) deep. The Model 101E base cost is 

$12,100. As configured for this verification test, the cost would be $14,180. 

2
Chapter 3 

Test Design and Procedures

3.1 Introduction 

H2S is formed at animal feeding operations (AFOs) during the bacterial decomposition of sulfurcontaining organic compounds present in manure. Also known as a component of sewer gas, H2S 

has the characteristic odor of rotten eggs and, at high levels [greater than 500 parts per million 

(ppm)], can cause death from even brief exposure. As a result, H2S analyzers were identified as a 

priority technology category through the AMS Center stakeholder process. 

This verification test was conducted according to procedures specified in the Test/QA Plan for 

Verification of Ambient Hydrogen Sulfide Analyzers at a Swine Finishing Farm,

(1)

 with the 

exception of three deviations that are addressed later in this report. The testing was conducted at 

a large swine finishing farm near Ames, Iowa. Testing was conducted for six weeks between 

April 25 and June 3, 2005, during which time the Model 101E continuously measured H2S 

concentrations in ambient air or synthetic air samples of known concentration (“standards”). The 

performance of the Model 101E was evaluated in terms of 

P Accuracy 

P Bias 

P Precision 

P Linearity 

P Span and zero drift 

P Response time 

P Interference effects 

P Comparability 

P Data completeness 

P Operational factors. 

3.2 Site Description 

The layout of the swine finishing farm is shown in Figure 3-1. The farm had ten animal barns, 

arranged in two parallel rows of five, with each barn housing up to 2,000 swine. Figure 3-2 

shows the interior of a swine barn; natural ventilation was regulated by raising or lowering 

curtains, shown in the foreground. The urine and feces from the swine leave the barns through 

wood slats in the floor and are flushed through underground piping into a nutrient lagoon located 

on the southern end of the farm; supernatant liquid from the primary lagoon is pumped into a 

secondary storage lagoon and used to fertilize nearby fields. The primary H2S source was 

expected to be the lagoons. The perimeter of the farm is lined with trees, and agricultural fields 

3
surround the perimeter. A temperatureregulated instrument trailer was placed 

on-site during the test to house the 

monitoring equipment and to provide a 

sheltered work space. Figure 3-3 shows the 

test site as photographed from the south of 

the lagoons, showing the instrument trailer 

and swine barns in the background. The 

Model 101E was installed inside the 

instrument trailer, and a Teflon inlet line 

(sampling ambient air through the East 

window) was connected to a Teflon 

manifold and was used to sample ambient 

air. The Teflon inlet line was protected 

from rain by an inverted funnel. The Teflon 

manifold used for supplying ambient air 

and gas standards to the Model 101E is 

shown in Figure 3-4. Sample tubing 

lengths were minimized both for ambient 

air sampling and for delivery of gas 

standards. 

3.3 Test Design 

Table 3-1 shows the activities involved in 

preparing for and conducting the 

verification test. 

Curtain 

Figure 3-2. Swine Barn Interior 

Farm

Office

Entrance 

N 

Trailer 

Primary Secondary 

Nutrient Storage 

Lagoon Lagoon 

Figure 3-1. Test Site 

The Model 101E was installed 

at the test site by vendor 

representatives. Battelle and 

USDA staff worked with the 

vendor representatives to 

establish procedures for 

operating the Model 101E 

during this verification test. 

The vendor representatives 

trained Battelle and USDA 

staff to check several 

instrument parameters to 

verify the operation of the 

Model 101E and identify signs 

of malfunction. A checklist, 

provided by the vendor representatives and included as 

Appendix A, was completed 

daily (Monday through Friday) 

4
Figure 3-3. Test Site Lagoons 

by Battelle or USDA staff. In general, Battelle or USDA staff verified 

that the Model 101E power was on, checked for alarms, inspected the 

inlet filter, and downloaded the Model 101E data (recorded as oneminute averages) on a daily basis. In the event of an instrument 

malfunction, Battelle and/or USDA staff could contact the vendor 

representatives or Teledyne-API customer service and conduct minor 

troubleshooting procedures as necessary, but were not expected to 

make any major repairs. The vendor representatives remained on-site 

until the installation was complete. All the testing activities, which are 

described in the following sections, were conducted by Battelle and/or 

USDA staff. 

Individual data files (comma-delimited text) were opened in Microsoft 

Excel, where the results were analyzed using the procedures outlined in 

Chapter 5 of this report. Daily files containing only the Model 101E 

H2S measurement data were less than 100 kilobytes. Files containing 

all of the stored Model 101E data (approximately 7 days), which 

contained the H2S measurement data and operating parameters, were 

approximately 1 megabyte in size. 

Gas standard dilutions were supplied to the Model 101E during testing 

activities for 20 minutes using a programmable dilution system 

(Environics Series 4040, with silanized internal components) that 

supplied each mixture to the Teflon manifold at flow rates at least 1 

Lpm in excess of the Model 101E sampling flow rate (approximately 

0.65 Lpm). The Model 101E logged one-minute averages of the 

instantaneous H2S readings. The average Model 101E response to each 

gas standard was calculated from the last 5 minutes of data from each 

delivery period (5 data points). The last five minutes were selected 

because the Model 101E response appeared to be stable during that 

period (i.e., a general increase or decrease in the response was not 

apparent). These average Model 101E response values were used in the 

calculations described in Chapter 5 of this report. 

5

Figure 3-4. Teflon 

Manifold 
Table 3-1. Test Activities 

Week of Activities 

April 11 • Install Model 101E 

• Establish inlet connections 

April 18 • Training of USDA and Battelle staff by vendor representatives 

• Conduct trial operations 

April 25

(Testing Week 1)

May 2

(Testing Week 2)

May 9

(Testing Week 3)

May 16

(Testing Week 4)

May 23

(Testing Week 5)

May 30

(Testing Week 6)

• Zero air/H2S standard challenge for analyzer response (baseline) and 

analyzer response time 

• Multipoint H2S standard challenges for accuracy, bias, precision, linearity 

• One zero/span check 

• Three time-integrated reference samples collected and analyzed 

• Routine operation 

• Three zero/span checks 

• Three time-integrated reference samples collected and analyzed 

• Install in situ reference method instrumentation at test site 

• Routine operation 

• Two zero/span checks 

• Five time-integrated reference samples collected and analyzed 

• Routine operation 

• Repeat zero air/H2S standard challenge for analyzer response (baseline) 

and analyzer response time 

• Three zero/span checks 

• Four time-integrated reference samples collected and analyzed 

• Multipoint H2S standard challenges for accuracy, bias, precision, linearity 

• Routine operation 

• Two zero/span checks 

• Multipoint H2S standard challenges for accuracy, bias, precision, linearity 

• Gas standard challenges for interference check 

• Troubleshoot in situ reference method instrumentation 

• Begin in situ reference measurements 

• Routine operation 

• Three zero/span checks 

• Continue in situ reference method measurements 

• Demobilize in situ reference method instrumentation 

• Remove Model 101E from test site 

6
The Model 101E H2S readings when sampling ambient air were compared to concurrent 

measurements by two H2S reference methods. For comparison with the time-integrated reference 

method (described in Section 3.3.5.1), the Model 101E H2S readings were averaged to the same 

time period over which the reference method samples were collected (approximately 7.5 hours). 

For comparison with the in situ reference method (described in Section 3.3.5.2), Model 101E 

readings were averaged over 15-minute periods, centered on the in situ reference method sample 

times. The performance results of the Model 101E during this verification test are presented in 

Chapter 6 of this report and summarized in Chapter 7. 

3.3.1 Accuracy, Bias, Precision, and Linearity 

Three times during the verification test, the Model 101E was challenged with a certified 

compressed H2S gas standard [5.12 parts per million (ppm) H2S, Scott Specialty Gases] diluted 

in zero air to achieve measurements over a range of concentrations from approximately 0 to 300 

parts per billion (ppb). Three non-consecutive measurements were recorded at each of five 

nominal concentration levels. Each concentration was supplied to the Model 101E for 

20 minutes. Table 3-2 shows the nominal H2S concentrations supplied to the Model 101E and 

the order in which they were supplied. As Table 3-2 indicates, the H2S concentrations were 

supplied to the Model 101E in increasing order, then in random order, and finally in decreasing 

order. After the last measurement was recorded, the Model 101E was returned to sampling 

ambient air. 

Table 3-2. H2S Concentrations and Order for Multipoint Challenges 

Concentration 0 ppb 30 ppb 90 ppb 150 ppb 300 ppb 

1 2 3 4 5 

Measurement 

Number 

7 10 6 9 8 

15 14 13 12 11 

The Model 101E response to the series of H2S gas standards was used to evaluate accuracy, bias, 

precision, and linearity. The statistical procedures used are presented in Section 5. Accuracy was 

calculated at each concentration and for each replicate relative to the nominal H2S concentration. 

Bias was calculated for each series of multipoint H2S challenges. The Model 101E precision was 

demonstrated by the reproducibility of the average Model 101E response at each nominal H2S 

concentration. Linearity was assessed by establishing a multipoint calibration curve from the 

Model 101E response. 

3.3.2 Span and Zero Drift 

The baseline response of the Model 101E to zero air and a 30-ppb dilution of a compressed H2S 

gas standard was determined during the first week of testing. The Model 101E was challenged 

alternately with the diluted H2S gas standard and zero air, for a total of five replicates of both the 

gas standard and zero air. Each gas was supplied sequentially for 20 minutes and the average 

response calculated for each replicate using data from the last 5 minutes of each delivery period. 

7
The overall average and standard deviation of the Model 101E response to zero air and to the 

30-ppb H2S standard were calculated from the average response for the five replicates. Control 

charts showing the warning (± 2 SD) and action (± 3 SD) limits were constructed for the span 

and zero response for use in evaluating drift. The Model 101E was challenged with the zero air 

and 30-ppb H2S sequence again during the fourth week of testing, and the results are presented in 

this report; however, the action and warning limits were not adjusted. Thus, drift was evaluated 

for the full duration of the verification test relative to the Week 1 response. 

At least twice each week, zero air and a 30-ppb H2S standard were supplied to the Model 101E 

for 20 minutes for a total of 14 zero/span checks. The gas standard dilution system was not 

flushed with the H2S gas standard before performing eight of the span checks. Thus, the results 

of six span drift checks were used to evaluate span drift. Each response was compared to the 

Week 1 baseline response to determine whether drift occurred in the Model 101E sensitivity to 

zero air or the 30-ppb H2S standard. 

3.3.3 Response Time 

The data collected during the Week 1 and Week 4 zero/span baseline response checks were used 

to determine the Model 101E response time. The 95% rise time was calculated for changes from 

zero air to the 30-ppb H2S standard, and the 95% fall time was calculated for changes from the 

30-ppb standard to zero air. A minimum of three individual measurements was used to determine 

the average rise and fall times. 

3.3.4 Interference Effects 

The Model 101E was challenged with a series of gases (Table 3-3) that may be present at an 

AFO and could interfere with the Model 101E response to H2S. Each interferant was supplied at 

either 100 or 500 ppb, as listed in Table 3-3, in the presence and absence of 100 ppb of H2S. A 

100-ppb H2S standard was supplied to the Model 101E for 20 minutes, and the responses were 

recorded. The Model 101E was then supplied with zero air for five minutes. The first interferant 

was diluted with zero air and delivered to the Model 101E for 20 minutes. After the responses 

were recorded, the Model 101E was supplied with zero air for five minutes. A mixture of the 

first interferant at (SO2) 100 ppb with 100-ppb H2S in zero air was supplied to the Model 101E 

for 20 minutes. The Model 101E responses were recorded, and zero air was supplied to the 

Model 101E for approximately five minutes. This process was repeated for each interferant at 

the concentrations listed in Table 3-3. 

3.3.5 Comparability 

The comparability of the Model 101E response to ambient air was evaluated by comparing its 

response to two H2S reference methods (time-integrated and in situ), which were carried out by 

USDA and Applied Measurement Science. The two reference methods were based on American 

Society of Testing Materials (ASTM) Method D5504-01,(2)

 with the following substitution: 

pulsed flame photometric detection (PFPD) was used instead of sulfur chemiluminescence 

detection. Reference H2S measurements in ambient air were conducted using gas chromatography (GC) with PFPD using two sample collection techniques. Although the analytical 

approach of the two methods was the same, they differed in sample collection and handling. 

8
Table 3-3. Interferants and Approximate Concentrations for Interference Checks 

Interferant Approximate 

Concentration (ppb) 

Sulfur dioxide 100 

Carbonyl sulfide 100 

Carbon disulfide 100 

Methyl mercaptan 100 

Dimethyl sulfide 100 

Hydrocarbon blend 

(mixture of C1 to C6 alkanes) 500 

Ammonia 500 

The two reference methods were not conducted simultaneously; therefore the results of the two 

methods could not be compared. As discussed in Section 4.1, not all of the QC requirements of 

the time-integrated and in situ reference methods were satisfied and, consequently, the quality of 

the reference method data was not confirmed. Therefore, in addition to the linear regression 

analysis described in the test/QA plan,

(1) the reference method data were compared to the Model 

101E data in a more qualitative manner. The Model 101E data were compared to the reference 

method data to determine whether the measured H2S concentrations were statistically 

significantly different at the 95% confidence level, and the linear regression analysis was 

repeated including only those data that were not significantly different. 

3.3.5.1 Time-Integrated Comparability 

Time-integrated reference measurements were conducted by collecting ambient air samples over 

relatively long periods (up to eight hours) in evacuated 1.4-liter Silonite canisters (Entech 

Instruments, Inc.) and were taken to the USDA laboratory for analysis. Ambient air was drawn 

into the evacuated canisters from the same Teflon manifold to which the Model 101E was 

connected. The canisters were fitted with a silanized Entech flow controller and pressure gauge 

to restrict the air flow to approximately one to three standard cubic centimeters per minute 

(sccm), allowing the canisters to fill slowly over approximately eight hours. A performance 

evaluation (PE) audit of the canister sampling flow rate revealed that the flow rate varied 

between 1.01 and 2.52 sccm over 7.5 hours. The variability in the canister sampling flow rate 

could result in uneven weighting of the time-integrated air sample collected in the canister, 

potentially resulting in biased results. Samples were collected during the following time periods: 

April 29 to 30, May 4 to 5, May 11 to 13, and May 18 to 21. Up to three samples were collected 

over eight-hour intervals on each sampling day according to the following approximate 

schedule: 10:00 p.m. to 6:00 a.m., 6:00 a.m. to 2:00 p.m, and 2:00 p.m. to 10:00 p.m. 

The Silonite canisters were cleaned before sample collection using an Entech 3120a Canister 

Cleaning System by heating under vacuum at 120EC, filling with humidified nitrogen, and 

9
evacuating to a pressure of 50 millitorr. This process was repeated for 50 cycles. Canisters were 

then transported to the test site for sampling and returned to the laboratory for analysis. Canisters 

were sampled using an Entech 7500 Series Robotic Autosampler, which was connected to an 

Entech 7100A Preconcentrator and an Agilent 6890 GC with an OI Analytical PFPD. Canisters 

were heated to 100EC during sample transfer, and all transfer lines were maintained at 100EC. 

Helium carrier gas was used at a flow of 16 sccm. A sample of known volume [10 to 

400 standard cubic centimeters (scc)], depending upon the expected concentration, was 

withdrawn from the canister, trapped on glass beads at -20EC (the bead trap was subsequently 

desorbed at 10EC), and collected on a Tenax® trap at -80EC to reduce water in the system. The 

Tenax trap was heated to 180EC and the desorbed components were cryofocused at -150EC 

before a final heating and transfer to the GC column. The column was a GS-Gaspro, 60 meter 

(m) × 0.32 mm inner diameter (i.d.) capillary column (J & W Scientific). The column was held 

at 35EC for 0.5 minutes, ramped to 230EC at 12EC per minute, and held at 230EC for the 

remainder of the approximately 20-minute run. The test/QA plan(1)

 stated that samples would be 

analyzed within 24 hours of collection. It was not always possible to analyze the canisters within 

the 24-hour time frame; in some cases, samples could not be analyzed until 4 days after 

collection because of instrument availability. The longer holding times may have resulted in H2S 

loss in the canisters, and consequently to artificially low H2S reference measurement results. 

Sample degradation in the canister was not verified since a holding time study was not performed on ambient air samples. The test/QA plan(1)

 stated that the acceptability of the 24-hour 

holding time would be verified on an ambient air sample. A deviation report was filed to address 

the holding time issues. A multipoint calibration curve from approximately 150 to 2,300 

picograms (pg) for H2S was constructed daily (before reference analyses were conducted) by 

injecting several volumes of a diluted H2S compressed gas standard (5.12 ppm H2S, Scott 

Specialty Gases) onto the GC-PFPD. Instrument blanks (i.e., zero-volume injections) were 

included in each analytical run. Based on the instrument blank results, the quantitation limit 

(average blank result plus 10 times the standard deviation of the blank) for a 10-scc injection 

was 2.2 ppb. 

3.3.5.2 In Situ Comparability 

In situ reference measurements were conducted by Applied Measurement Science. The 

instrumentation for the in situ method was installed in the instrument trailer at the test site. Air 

samples were drawn from a Teflon tube whose inlet was collocated with the Teflon manifold 

sampling inlet at a flow rate of approximately 5 Lpm to reduce the residence time of ambient air 

in the inlet. Volatile compounds in the samples were cryotrapped, thermally desorbed, and 

injected directly onto a Varian 3800 GC with PFPD. The duration of sample collection was 

adjusted so that the mass of H2S was maintained, to the extent possible, within the range of the 

PFPD system, nominally from 30 pg to 3,000 pg per sample. Sample collection times varied 

between 6 seconds and 8 minutes. The column was a GS-Gaspro 30- m × 0.32-mm i.d. capillary 

column (J & W Scientific). Helium carrier gas was used at a flow of 2 sccm. The column was 

held at -10EC for 2 minutes, ramped to 200EC at 40EC per minute, and held at 200EC for the 

remainder of the approximately 20-minute run. Multilevel calibrations were performed using the 

same certified H2S gas standard (5.12 ppm H2S, Scott Specialty Gases) and programmable 

dilution system used for performing testing activities. In situ reference measurements were 

conducted as frequently as possible (usually every 16 minutes) over a four-day period at the end 

of the verification test. Due to technical problems with the reference method air sampling valve 

system, measurements could not be conducted over the ten days specified in the test/QA plan.(1) 

10
Of the ambient air measurements conducted by the in situ reference method, 41 of the 53 

reference measurements could be used for comparison to the Model 101E results. The other 12 

measurements were presented as upper (result below quantitation limit) or lower (saturated H2S 

peak) limits. 

3.3.6 Data Completeness 

Data completeness was assessed based on the overall data return achieved by the Model 101E. 

3.3.7 Operational Factors 

Operational factors such as maintenance needs, data output, consumables used, ease of use, and 

repair requirements were evaluated based on the observations of Battelle and USDA staff. 

11
Chapter 4 

Quality Assurance/Quality Control

QA/quality control (QC) procedures were performed in accordance with the quality management 

plan (QMP) for the AMS Center(3)

 and the test/QA plan for this verification test

(1)

 with the 

exception of three deviations, which have been addressed in this report. First, the time-integrated 

reference method canister flow rate was lower than expected. This deviation did not impact the 

quality of this verification test. The second deviation from the test/QA plan(1)

 involved the 

reference method QC requirements, which were not fully satisfied. Third, the pre-analytical 

holding time for ten of the 15 time-integrated reference samples was longer than 24 hours. As 

discussed in Section 4.1 and Section 3.3.5.1, the second and third deviations did impact the 

comparisons that were performed with the reference method data. 

4.1 Reference Method Quality Control Results 

Table 4-1 summarizes the reference method QC requirements. Both reference methods were 

required to analyze continuing calibration verifications (CCV), QC samples (QCS), and field 

blanks. The time-integrated H2S reference method was also required to repeat analysis of 10% of 

the samples to verify method precision. 

4.1.1 Time-Integrated Reference Method Quality Control Results 

It was determined that the USDA laboratory GC-PFPD system required calibration each day 

before analysis of reference samples. This eliminated the need for running CCV samples, so 

there was no expectation for agreement to previous calibration results. QCSs were not run as 

frequently as stated in Table 4-1, but often were included at the end of the analysis run. 

Approximately half of the analysis runs had at least one QCS that passed the requirement listed 

in Table 4-1. The other half either had failed QCSs or none were included in the run. Replicate 

H2S precision was not determined for the same injection volume. However, the results for four 

out of 13 comparisons of variable-volume injections from the same sample were within 30% of 

one another by percent difference (%D). Measurement accuracy results are discussed in more 

detail in Section 4.2.1. Briefly, four PE samples were submitted to the USDA laboratory; 

reference method results for two of the samples were within the acceptance criterion for 

measurement accuracy. The other two results were 38% and undetectable H2S levels. Finally, 

two field blank samples were submitted to the USDA laboratory for analysis, and both resulted 

in undetectable H2S levels by the GC-PFPD system. Since the QC requirements for 

12
Table 4-1. Reference Method Quality Control Requirements and Target Acceptance 

Criteria 

QC Parameter Addressed By Required Performance 

CCV CCV run before analysis of reference 

samples each day 

%D of CCV result within 30% 

of expected value 

QCS QCS run every 4 hours and after analysis 

of reference samples each day 

%D of QCS result within 30% 

of expected value 

Replicate H2S 

precision 

Analyze 10% of all samples twice(a) %D within 30% of one another 

Measurement 

accuracy 

Analyze H2S standard from independent 

source(b) 

Results within 30% of expected 

value 

Field blanks Analyze canisters filled with zero air 

recovered from the test site (weekly)

(a) 

Analyze zero air passed through sample 

manifold (weekly)

(c) 

If blank >30% of sample, H2S, 

data must be flagged 

(a)

 Time-integrated H2S reference method only. (b)

 This standard was provided as part of the PE audit. (c) In situ H2S reference method only. 

the time-integrated reference method were not satisfied, the results were not quantitatively 

compared to the Model 101E both quantitatively and qualitatively [i.e., to determine whether 

they were significantly different from each other at the 95% confidence level (see Section 5.8, 

Comparability)]. 

4.1.2 In Situ Reference Method Quality Control Results 

CCV samples were run each day when the in situ reference method was conducting ambient 

measurements. If results were not within 30% of the expected value by %D, a multilevel 

calibration curve was generated. At least once daily, a QCS or measurement accuracy sample 

was analyzed. Six QCS samples were analyzed, and all were within 30% of the expected 

concentration by %D. QCS samples from a second gas standard (110 ppb H2S, Air Liquide) were 

analyzed six times. Two results fell outside of the calibration curve, and one was outside of the 

acceptance criterion; three results met the acceptance criterion. One QCS from a third gas 

standard (4.78 ppm H2S, Scott Marrin) was made and was within 30% of the expected value. The 

measurement precision of four analyses of a 10-ppb H2S standard was 8.1% RSD, which would 

relate to a %D value less than 30%. Three out of four measurement accuracy samples delivered 

as PE audit samples were within the acceptance criterion. Once during the verification test, the in 

situ reference method sampled zero air delivered through the ambient air inlet. The measurement 

result was 3.1 ppb, which is approximately the same as the method quantitation limit for a 

50-cubic-centimeter sample (200 pg/sample). Since the QC requirements for the in situ reference 

method were not all satisfied, the results were compared to the Model 101E data both 

quantitatively and qualitatively [i.e., to determine whether they were significantly different from 

each other at the 95% confidence level (see Section 5.8, Comparability)]. 

13
4.2 Audits 

4.2.1 Performance Evaluation Audits 

A PE audit was conducted to assess the quality of the H2S reference method measurements. In 

the PE audit, key aspects of the reference measurements were checked by comparing them with 

an independent National Institute of Standards and Technology- (NIST-) traceable standard. The 

PE audit of the H2S reference methods was performed by supplying to each reference method a 

blind, independent, NIST-traceable H2S standard provided by Battelle. The output of a certified 

H2S permeation tube (VICI Metronics, held at 30EC) was diluted in ultra-high purity (UHP) zero 

air (approximately 2.7 to 3.9 Lpm) to produce H2S concentrations between 60 and 90 ppb. The 

PE samples were analyzed in the same manner as the ambient air samples, and the analytical 

results for the PE samples were compared to the nominal concentration. The target criterion for 

the PE audit was agreement of the analytical result within 30% of the nominal H2S 

concentration. If the PE audit results did not meet the tolerances required, they were repeated. 

PE audits of the reference methods were required to be performed once prior to the start of the 

test and two times during the test, at a minimum. A total of four PE audit samples each were 

submitted to the USDA laboratory and to the in situ reference method for analysis. The USDA 

time-integrated reference method results for the first and last PE audit samples met the 

acceptance criterion, while the other two did not. The in situ reference method result met the 

acceptance criterion for the first, third, and fourth PE audit sample. 

A PE audit of the ambient air sample flow rate for the time-integrated reference method was 

performed by comparing it to an independent flow measurement device. The target criterion for 

this PE audit was in agreement within the expected range (i.e., 2 to 3 sccm). The PE audit of the 

canister air sampling rate revealed that the actual flow rates for the Entech Flow Controller used 

for this verification test ranged from 1.01 to 2.52 sccm over 7.5 hours. The flow controller was 

not adjusted to increase the flow rates since this would have the undesirable effect of shortening 

the time-integrated sample duration. This deviation from the test/QA plan(1)

 was filed. This 

deviation did not impact the quality of this verification test since the actual flow rate is not used 

in the reference method analysis. However, variability in the canister sampling flow rate over the 

7.5-hour collection time would impact the comparability of the air collected in the canister and 

that sampled by the Model 101E. 

A PE audit of the programmable dilution system was performed by comparing its output to an 

independent flow measurement device. One mid-range flow rate was audited for each flow 

controller (i.e., 0.03, 0.3, and 5 Lpm) within the dilution system. The target criterion for this PE 

audit was agreement within 5% of the flow readings; all measured flows agreed within 5%. 

These audits were performed once during the verification test. 

4.2.2 Technical Systems Audits 

The Battelle Quality Manager performed a technical systems audit (TSA)on April 28 and 29, 

2005, to ensure that the verification test was being performed in accordance with the AMS 

Center QMP,

(3)

 the test/QA plan,

(1)

 ASTM method D5504-01,(2) and any standard operating 

procedures (SOPs) used by USDA or Applied Measurement Science. In the TSA, the Battelle 

Quality Manager toured the test site and the USDA Laboratory, observed the H2S reference 

14
method sampling and sample recovery, inspected documentation of H2S sample chain of 

custody, and reviewed Model 101E-specific record books. 

The Battelle Quality Manager also reviewed the reference methods used, compared actual test 

procedures to those specified by the test/QA plan,(1)

 and reviewed data acquisition and handling 

procedures. 

Observations and findings from this audit were documented and submitted to the Battelle 

Verification Test Coordinator for response. No findings were documented that required any 

corrective action. The records concerning the TSA are stored for at least seven years with the 

Battelle Quality Manager. 

4.2.3 Audit of Data Quality 

At least 10% of the data acquired during the verification test were audited. Battelle’s Quality 

Manager or his designee traced the data from the initial acquisition, through reduction and 

statistical analysis, to final reporting, to ensure the integrity of the reported results. All 

calculations performed on the data undergoing the audit were checked. 

4.3 Quality Assurance/Quality Control Reporting 

Each assessment and audit was documented in accordance with Sections 3.3.4 and 3.3.5 of the 

QMP for the ETV AMS Center.

(3)

 Once the assessment report was prepared, the Battelle 

Verification Test Coordinator ensured that a response was provided for each adverse finding or 

potential problem and implemented any necessary follow-up corrective action. The Battelle 

Quality Manager ensured that follow-up corrective action was taken. The results of the TSA 

were sent to the EPA. 

4.4 Data Review 

Records generated in the verification test were reviewed before these records were used to 

calculate, evaluate, or report verification results. Table 4-2 summarizes the types of data 

recorded. The review was performed by a technical staff member involved in the verification 

test, but not the staff member who originally generated the record. The person performing the 

review added his/her initials and the date to a hard copy of the record being reviewed. 

15
Table 4-2. Summary of Data Recording Process 

Data to Be 

Recorded Where Recorded How Often 

Recorded By Whom Disposition of 

Data 

Dates, times, and ETV laboratory Start/end of test Battelle if on-site; Used to organize 

details of test record books or procedure, and at USDA if Battelle and check test 

events, Model data recording each change of a not on-site results; manually 

101E forms test parameter or incorporated in 

maintenance, change of Model data spreadsheets 

down time, etc. 101E status as necessary 

Model 101E ETV laboratory At Model 101E Electronic data by Incorporated in 

calibration record books or calibration or vendor; Battelle if verification report 

information electronically recalibration on-site; USDA if as necessary 

Battelle not onsite 

Model 101E H2S Recorded Recorded Model 101E Converted to 

readings electronically by continuously vendor, for spreadsheet for 

each Model 101E transfer to statistical analysis 

and then Battelle if on-site; and comparisons 

downloaded to transfer to USDA 

computer at least if Battelle not onweekly site 

Reference sample Laboratory record Throughout USDA and Retained as 

collection books and sampling and Applied documentation of 

procedures, electronically by analysis processes Measurement reference method 

reference method analytical method Science performance 

procedures, 

calibrations and 

QA data, etc. 

Reference method Electronically Every sample Applied Entered into or 

H2S analysis from H2S analysis Measurement converted to 

results analytical method Science spreadsheets for 

calculation of 

Hard-copy Every sample USDA ambient H2S 

printouts and data analysis results and 

sheets statistical analysis 

and comparisons 

16
Chapter 5 

Statistical Methods and Reported Parameters

The statistical methods presented in this chapter were used to verify the performance parameters 

listed in Section 3.1. The average measured Model 101E response values (Y) used in the 

calculations presented in this section were calculated from the last 5 data points (five minutes) of 

each testing condition (e.g., H2S gas standard or other gas challenge). 

5.1 Accuracy 

Accuracy of the H2S Model 101E with respect to the individual H2S gas standards was assessed 

as the percent recovery (%R), using Equation 1: 

⎡ ⎛ Y X− ⎞⎤ (1) %R =

⎣

⎢1+ ⎝

⎜ X ⎠

⎟

⎦

⎥ ×100 

where Y is the average measured Model 101E response (as defined in Section 3.3.) and X is the 

nominal H2S gas standard concentration. The average, minimum, and maximum %R values are 

reported for each series of multilevel H2S challenges. A %R value of 100% indicates perfect 

agreement between the averaged measured Model 101E response and the nominal H2S gas 

standard concentration. 

5.2 Bias 

Bias of the Model 101E was defined as a systematic error in measurement that resulted in 

measured error that was consistently positive or negative compared to the true value. The bias 

was calculated as the average %D of the Model 101E compared to the nominal H2S gas standard 

concentration and was calculated for each series of multipoint H2S challenges, using Equation 2: 

%D = 1 ∑

k 

⎝

⎜

⎛ Y X−

⎠

⎟

⎞

× 100 (2) k i=1 X i 

where k is the number of valid comparisons, and Y and X are the same as in Equation 1. 

17
5.3 Precision 

The precision of the Model 101E was evaluated from the triplicate responses to each H2S gas 

standard supplied during the multipoint H2S challenges (outlined in Table 3-2). The precision 

was defined as the percent relative standard deviation (%RSD) of the averaged triplicate 

measurements and calculated for each H2S concentration listed in Table 3-2, using Equations 3 

and 4: 

∑ (Y− Y)

2 

(3) SD = n − 1 

%RSD = SDi 

i × 100 (4) Yi 

where Y is the average Model 101E response calculated from the last 5 data points (5 minutes) 

of each gas standard delivery period, Yi is the overall average of the Y values at H2S 

concentration i (i = 30, 90, 150, and 300 ppb), and n is the number of measurements (3). The 

overall average %RSD was calculated for each series of multipoint H2S challenges and included 

the %RSD for all H2S concentrations tested. 

5.4 Linearity 

Linearity was assessed by a linear regression analysis using the diluted H2S standard gas 

concentrations as the independent variable and results from the Model 101E being tested as the 

dependent variable. Linearity was expressed in terms of slope, intercept, and coefficient of 

determination (r

2

). 

5.5 Span and Zero Drift 

The baseline response of the Model 101E to zero air and the 30-ppb H2S standard was 

established during the first week of testing. The overall average (Y) and standard deviation (SD) 

of the Model 101E response to zero air and the 30-ppb H2S standard were calculated from the 

average Model 101E responses from each of the five replicate measurements conducted during 

the first week of testing. From these values, a control chart was constructed, and the Y± 2SD

“warning limit” and the Y± 3SD “action limit” were calculated. Span drift was defined as 

having occurred if three consecutive span checks fell either above or below the warning limit. 

Zero drift was defined as having occurred if three consecutive zero checks fell either above or 

below the warning limit. 

5.6 Response Time 

Response time was assessed in terms of both the rise and fall times of the Model 101E when 

sampling the 30-ppb H2S gas standard and zero air on the first day of testing. Rise time (i.e., 0% 

18
to 95% response time for the change in H2S concentration) was determined from the Model 101E 

response to a rapid increase in the delivered H2S concentration. Once a stable response was 

achieved with the H2S standard, the fall time (i.e., the 100% to 5% response time) was 

determined in a similar way, switching from the H2S standard back to zero air. 

5.7 Interference Effects 

The interference effects of the Model 101E were calculated in terms of the ratio of the response 

of the Model 101E to the interferant relative to the actual concentration of the interfering 

species. For example, if 100 ppb of an interfering species resulted in a 1-ppb change in the 

response of the Model 101E, the interference effect was reported as 1% (i.e., 1 ppb/100 ppb). 

Interference effects are reported separately for each interferant both in the absence and in the 

presence of H2S in zero air. 

5.8 Comparability 

The comparability of the Model 101E results and the time-integrated and in situ reference 

methods with respect to ambient air was assessed by linear regression using the reference 

method H2S concentrations as the independent variable and the results from the Model 101E as 

the dependent variable. The Model 101E H2S measurements were averaged over the appropriate 

sample collection period for each reference method (i.e., approximately 7.5 hours or 

15 minutes). Comparability was calculated separately for the time-integrated and in situ 

reference methods and was expressed in terms of slope, intercept, and r2

. 

The linear regression analysis was repeated for each reference method, including only the 

reference method results that were not significantly different from the Model 101E average 

results at the 95% confidence level. The 95% confidence interval (CI) was calculated for each 

Model 101E average, using Equation 5: 

t × SD 95%CI = Y ± (5) 

n 

where Y is the average Model 101E response over the sample collection period, SD is the 

standard deviation of the Model 101E data over the sample collection period, n is the number of 

Model 101E readings used in the average, and t is the t-value of the Student’s t-distribution for 

95% confidence level and the degrees of freedom (n-1). The calculated 95% CI for each Model 

101E average was compared to the corresponding reference measurement value to determine 

whether the results were statistically significantly different at the 95% confidence level. For 

comparison to the time-integrated reference method, the Model 101E readings used for each 

average (approximately 7.5 hours) were plotted as a histogram to determine whether they were 

normally distributed. Most of the samples (13 out of 14) were best represented by a log-normal 

distribution. For those samples, the natural logarithms (ln) of the Model 101E and reference 

measurements were used to calculate the 95% CI and to determine whether the results were 

significantly different at the 95% confidence level. This approach was also applied to the in situ 

H2S reference method, using the Model 101E averages over 15-minute intervals, centered on the 

19
in situ reference measurement times. The Model 101E readings used to compare to the in situ 

reference method were assumed to be normally distributed. 

5.9 Data Completeness 

Data completeness was calculated as the percentage of the total possible data return achieved 

over the entire field period. This calculation used the total hours of data recorded from each 

Model 101E, divided by the total hours of data in the entire field period. The field period was 

defined as beginning at 8:00 a.m. on April 25, 2005 and ending at 9:00 a.m. on June 3, 2005. No 

distinction was made in this calculation between data recorded during a specific test activity 

(e.g., data recorded for comparison to H2S reference method data) and that recorded during 

routine ambient air monitoring. 

20
Chapter 6 

Test Results

The results of the verification test of the Model 101E are presented in this section. The Model 

101E logged one-minute averages of the instantaneous H2S readings. The Model 101E zero 

value was set using UHP zero air and the span value was adjusted to a 400-ppb dilution from a 

certified compressed gas cylinder standard (100 ppm H2S, Scott Specialty Gases) that was 

independent of the gas standard used for performing this verification test (5.12 ppm H2S, Scott 

Specialty Gases). Although both standards were certified by the manufacturer to have accuracy 

better than ±5%, differences between the actual H2S concentration in the two cylinders may 

exist. Any differences between the two gas standards would be manifested in the accuracy and 

bias performance parameters evaluated during this test; other performance parameters such as 

linearity, precision, and interference effects would not be impacted by differences in the two gas 

standards because of the nature of these calculations. Gas standard dilutions for calibration and 

testing activities were prepared using the same dynamic dilution system. All Model 101E 

measurement data were analyzed and included in this report as output by the Model 101E. Any 

negative H2S concentration values should be considered to indicate measurements of H2S 

concentrations less than those in the zero air used to set the zero value and/or drift in the Model 

101E response. The Model 101E was calibrated twice prior to the start of the verification test 

(once after it was installed and again after the UV lamp was replaced, as described in Section 

6.10); no additional calibrations were performed over the duration of this verification test. 

Meteorological conditions collected by a nearby (less than 2 miles) meteorological station are 

presented in Figure 6-1. The ambient data set collected by the Model 101E is shown in the 

bottom panel, along with the wind direction, wind speed, and ambient temperature data. The 

average ambient H2S concentration measured by the Model 101E during the verification test was 

14.8 ppb, with a range of !2.2 to 843.9 ppb. The meteorological conditions, which were 

recorded as 1-hour averages, varied widely over the duration of the verification test. The average 

ambient temperature was 14.3EC, with a range of !4.9 to 29.0EC. The average Model 101E 

ambient H2S concentrations are shown in Figure 6-2 plotted on polar coordinates as a function of 

wind direction. When winds were from the south, the Model 101E was exposed to emissions 

from the nutrient lagoons. As shown in Figure 6-2, the highest H2S concentrations were observed 

during southwesterly winds, which passed across the primary nutrient lagoon before reaching the 

instrument trailer. During northerly winds, the Model 101E sampled barn emissions and 

measured much lower H2S concentrations. Winds were most frequently from the northwest and 

southeast, as shown by the diamonds in Figure 6-2. Under southerly winds, spikes in the 

measured H2S concentration were often observed at the start of rain, as shown in Figure 6-1. 

21
22

360 270 180 

90 

0

10

86420

20 10 

0 

800 Rain Events 600 400 200 

0 

5/1/2005 5/6/2005 5/11/2005 5/16/2005 5/21/2005 5/26/2005 

Figure 6-1. Meteorological Conditions and Model 101E Ambient H2S Measurements 

Hydrogen Sulfide (ppb) Temperature

Wind Speed Wi

nd Direction

(°C) (m•s 

-1) (de

grees) 
N

35 70 

4% 

8% 

W E

Averaged over 

15 degrees 

Centered at 

0 degrees 

ppb H2S 

S

Averaged Model 101E Hydrogen Sulfide Data 

Wind Direction Frequency (hourly averages) 

Number of Observations = 851 

Figure 6-2. Hourly Averaged Model 101E H2S 

Measurements Plotted as a Function of Wind 

Direction 

6.1 Accuracy 

Accuracy checks were conducted during Week 1, Week 4, and Week 5 of the verification test. 

The Model 101E was challenged with compressed H2S gas standards diluted in zero air at 

several concentrations (30 ppb to 300 ppb H2S). The H2S gas standards were diluted in zero air 

and delivered to the Teflon manifold at a flow rate of 3 to 4 Lpm, with a vent to ambient 

pressure. Accuracy checks were conducted during Week 1, Week 4, and Week 5 of the 

verification test. 

Figure 6-3 presents the H2S concentrations recorded by the Model 101E during each accuracy 

check gas challenge, along with the nominal H2S concentration levels supplied to the Model 

101E for Week 1, Week 4, and Week 5. The averages of the last five minutes (5 data points) of 

the measurements at each nominal H2S concentration and the calculated %R are presented in 

Table 6-1, along with the average %R for each week. The SD for each average measured 

concentration is also reported in Table 6-1 for reference purposes. As shown in Table 6-1, the 

Model 101E %R values ranged from 114% to 132%, with an average of 129% for the Week 1 

check. The Model 101E %R values for the Week 4 check ranged from 111% to 127% with an 

average of 124%. For the Week 5 check, the Model 101E %R values ranged from 113% to 

122%, with an average of 120%. Except for measurements of zero air, all of the Model 101E 

concentrations reported for Week 1 were higher than for Week 4, which were higher than 

Week 5. 

23
 Model 101E Measurement Data

 Nominal Hydrogen Sulfide Concentration 

400 

300 

200 

100 

0 

400 

300 

200 

100 

0 

400 

300 

200 

100 

0

Week 1 

Week 4 

Week 5 

00:00 01:00 02:00 03:00 04:00 05:00 

Elapsed Time (hours) 

Figure 6-3. Model 101E Accuracy Results 

H

ydrogen Sulfide (ppb) 

24
25

Table 6-1. Accuracy Results 

Week 1 Week 4 

H2S Gas Average(a) Average(a) Average(a) 

Standard Model 101E Model 101E Model 101E 

Measurement Concentration Response Response Response

Number (ppb) (ppb) SD (ppb) %R (ppb) SD (ppb) %R (ppb) 

1 0 -0.0 0.1 NA 0.5 0.1 NA 0.3 2 30 34.3 0.1 114 33.3 0.1 111 33.9 3 90 117.7 0.2 131 113.9 0.2 127 109.2 4 150 197.3 0.1 132 190 0.1 127 182.2 5 300 395 0.1 132 379.7 0.1 127 364.7 6 90 119 0.1 132 113.9 0.1 127 109.7 7 0 1.4 0.3 NA 0.9 0.1 NA 1.2 8 300 394.2 0.3 131 375.2 0.3 125 360.1 9 150 196.9 0.3 131 187.8 0.1 125 181.2 

10 30 38.5 0.3 129 36.4 0.2 121 35.6 

11 300 392.4 0.2 131 372.3 0.4 124 358.7 

12 150 196 0.5 131 186.6 0.4 124 180.6 13 90 117.8 0.1 131 111.8 0.1 124 108.3 14 30 38 0.1 127 36.2 0.1 121 35.5 15 0 0.6 0.0 NA 0.9 0.1 NA 1.2 

Average 129 124 Minimum 114 111 Maximum 132 127 Bias +2 (%D) 9 +24 

(a) Average Model 101E response calculated from the last 5 minutes of data collected during each gas standard delivery (n=5). NA = not applicable. 
6.2 Bias 

Bias in the Model 101E response to H2S gas standards was assessed for each of the accuracy 

checks presented in Section 6.1 and calculated separately for each sequence of multilevel H2S 

challenges. The Model 101E bias observed during the Week 1, Week 4, and Week 5 accuracy 

checks were +29%, +24%, and +20%, respectively. The consistently high bias is indicative of 

systematic error, which would also affect the Model 101E accuracy, and could be caused by a 

number of factors, including, but not limited to, differences in H2S gas standards used for 

calibration and testing activities, the gas standard dilution system, and Model 101E instrumental 

errors. The slow decrease in bias (from +29% to +20%) over the duration of the verification test 

is indicative of drift in the Model 101E sensitivity. The Model 101E bias values are presented in 

Table 6-1. 

6.3 Precision 

Table 6-2 presents the calculated precision of the Model 101E determined from the average 

Model 101E responses to the triplicate challenges at each H2S concentration level during the 

Week 1, Week 4, and Week 5 accuracy checks. The precision of the Model 101E reading varied 

from 0.3% to 6.3% during the Week 1 accuracy check, from 0.9% to 4.8% during the Week 4 

accuracy check, and from 0.4% to 2.7% during the Week 5 check. The highest %RSD values for 

each accuracy check were observed for the lowest concentration standard (30 ppb). The average 

precision calculated from each check was 1.9%, 2.0%, and 1.2% for Weeks 1, 4, and 5, 

respectively. 

Table 6-2. Calculated Precision of the Model 101E 

Week 1 Week 4 Week 5 

H2S Gas 

Standard 

Concentration 

(ppb) 

Overall Average 

Model 101E 

Response 

(ppb) %RSD 

Overall Average 

Model 101E 

Response 

(ppb) %RSD 

Overall Average 

Model 101E 

Response 

(ppb) %RSD 

30 36.9 6.3 35.3 4.8 35 2.7 

90 118.2 0.6 113.9 1.1 109.1 0.6 

150 196.7 0.3 188.1 0.9 181.3 0.4 

300 393.8 0.3 375.8 1.0 361.2 0.9 

Average %RSD 1.9 2 1.2 

26
6.4 Linearity 

Figure 6-4 shows the linearity results for the Week 1, Week 4, and Week 5 accuracy checks. For 

each check, a linear regression was calculated from the results presented in Table 6-1 (average 

Model 101E response versus the nominal H2S gas standard concentration) over the range of 0 to 

300 ppb. The 95% CI for the slope and intercept of the regression line were also calculated 

(shown in the following text within parenthesis). For Week 1, the slope of the regression line 

was 1.32 (± 0.02), with an intercept of -0.64 (± 2.6) and r2

 value of 0.9999. During Week 4, the 

linear regression showed a slope of 1.25 (± 0.02), an intercept -0.37 (± 3.5), and an r2

 of 0.9998. 

The linear regression analysis of the Week 5 data resulted in a slope of 1.20 (± 0.01), an 

intercept 0.24 (± 2.6), and an r2

 of 0.9999. Over the range of concentrations tested (0 to 300 ppb 

H2S), the Model 101E demonstrated a high degree of linearity. 

6.5 Span and Zero Drift 

The baseline response of the Model 101E to zero air and a 30-ppb H2S dilution was determined 

during the first week of the verification test and repeated during Week 4. The average responses 

of the Model 101E during each replicate delivery of zero air and 30 ppb H2S are shown in Table 

6-3. Each average utilized the last five data points for each zero air or H2S standard delivery. The 

warning ( Y± 2SD ) and action ( Y± 3SD ) limits were calculated for zero air and 30 ppb H2S 

and also are shown in the table. 

Span and zero drift checks were performed at least twice each week during the verification test, 

for a total of 14 drift checks, including the replicate challenges shown in Table 6-3 for Week 4. 

The gas standard dilution system was not flushed with the H2S gas standard before performing 

eight of the span checks prior to May 27, 2005. Results from these span checks are included in 

this report, but were not used to evaluate drift. The results of the span and zero drift checks are 

shown in Table 6-4. Each average utilized the last five data points for each zero air or H2S 

standard delivery. A control chart was prepared from the data shown in Tables 6-3 and 6-4 to 

demonstrate graphically whether drift occurred over the duration of the verification test. The 

control chart is shown in Figure 6-6. The Model 101E also was equipped with a zero air scrubber 

and H2S permeation tube, which allowed the Model 101E to perform automated internal span 

and zero checks. The Model 101E was configured to perform span and zero checks on a daily 

basis at 21:00, running zero air and the internal H2S permeation source for 20 minutes each. The 

last automated zero/span check was performed at the beginning of the fifth week of testing so 

that testing activities would not be interrupted by the automated checks. The average results of 

these automated span and zero checks are included in Figure 6-6. 

27
 Average Response Linear Fit 1:1 Line

400 

300 

200 

100 

0 

Analy

z

er Response (ppb) 

400 

300 

200 

100 

0 

400 

300 

200 

100 

0 

A 

B 

C

y = 1.32x - 0.64 

r 

2

 = 0.9999 

y = 1.25x - 0.37 

r 

2

 = 0.9998 

y = 1.20x + 0.24 

r 

2

 = 0.9999 

0 100 200 300 400

Nominal Hydrogen Sulfide (ppb)

Figure 6-4. Model 101E Linearity Results 

28
Table 6-3. Span and Zero Baseline Response 

Zero Response(a) 30-ppb Span Response(a) 

Min- Max- Min- MaxAverage SD imum imum Average SD imum imum 

Drift Check Date (ppb) (ppb) (ppb) (ppb) (ppb) (ppb) (ppb) (ppb) 

Week 1 

Wednesday -0.1 0.1 -0.1 0.0 35.2 0.4 34.6 35.4 

Week 1 

Wednesday 

0 0.1 -0.1 0.1 34.9 0.3 34.4 35.1 

Week 1 

Wednesday -0.1 0.1 -0.1 0.0 35.7 0.1 35.6 35.8 

Week 1 

Wednesday -0.1 0 -0.1 -0.1 35.7 0.1 35.5 35.8 

Week 1 

Wednesday 

0 0.1 -0.1 0.1 35.6 0.1 35.4 35.6 

Baseline Response -0.05 35.4 

Overall SD 0.03 0.3 

Warning Limit -0.1 – 0.0 34.7 – 36.1 

Action Limit -0.2 – 0.0 34.4 – 36.4 

Week 4 

Tuesday 

0.3 0.0 0.2 0.4 35.5 0.1 35.3 35.6 

Week 4 

Tuesday 

0.3 0.0 0.3 0.4 35 0.1 34.9 35.1 

Week 4 

Tuesday 

0.3 0.1 0.3 0.4 34.8 0.1 34.6 34.9 

Week 4 

Tuesday 

0.3 0.1 0.2 0.3 34.5 0.1 34.4 34.6 

Week 4 

Tuesday 

0.2 0.0 0.2 0.3 34.4 0.4 33.6 34.7 

Baseline Response 0.29 34.8 

Overall SD 0.05 0.4 

Warning Limit

(b) 0.2 – 0.4 34.0 – 35.7 

Action Limit

(b) 0.1 – 0.4 33.5 – 36.1 

(a)

 Statistics calculated from the last 5 data points (5 minutes) for each zero air or H2S standard challenge (n=5). (b) The warning and action limits for the Week 4 zero and 30-ppb H2S challenges are shown for reference purposes, but were not 

used for determining zero or span drift. 

29
Table 6-4. Span and Zero Drift Check Results 

Zero Check 30 ppb Span Check 

Mini- Maxi- Within Within Mini- Maxi- Within Within 

Check Average SD mum mum Warning Action Average SD mum mum Warning Action 

Number (ppb) (ppb) (ppb) (ppb) Limit? Limit? (ppb) (ppb) (ppb) (ppb) Limit? Limit? 

Week 1

Friday 

0.0 0.1 -0.1 0.0 Yes Yes 28(a) 0.3 27.7 28.3 (a) (a) 

Week 2

Monday -0.3 0.1 -0.4 -0.2 No No 14.7(a) 0.4 14.1 15.1 (a) (a) 

Week 2

Friday -0.2 0.2 -0.4 0.2 No No 12.2(a) 0.2 12 12.4 (a) (a) 

Week 

Saturd

2

ay -4.8 0.0 -4.8 -4.7 No No 25.7(a) 0.1 25.6 25.8 (a) (a) 

Week 

Monda

3

y 

0.7 0.0 0.7 0.8 No No 23.5(a) 0.1 23.5 23.6 (a) (a) 

Week 3

Friday 

0.4 0.1 0.3 0.4 No No 21(a) 0.6 20.4 21.9 (a) (a) 

Week 

Monda

4

y 

0.6 0.1 0.5 0.8 No No 36.3 0.1 36.2 36.3 No Yes 

Week

4(b) 0.4 0.1 0.2 0.3 No No 34.8 0. 4 34.4 35.5 Yes Yes 

Tuesday

Week 4

Thursday 

0.7 0.0 0.6 0.7 No No 31.5(a) 0.3 31.3 31.9 (a) (a) 

Week 4

Friday 

1.0 0.0 1.0 1.1 No No 34.8 0.1 34.7 34.9 Yes Yes 

Week 

Monda

5

y 

0.3 0.1 0.2 0.4 No No 24.7(a) 0.7 24 25.7 (a) (a) 

Week 5

Friday 

0.3 0.0 0.3 0.3 No No 34.5 0.1 34.4 34.6 No Yes 

Week 6

Sunday 

0.5 0.1 0.4 0.6 No No 35.5 0.1 35.3 35.6 Yes Yes 

Week 6

Tuesday 

0.0 0.0 0.0 0.1 No Yes 34.3 0.1 34.1 34.4 No No 

Week 

Thursd

6

ay 

0.3 0.1 0.2 0.4 No No 34.2 0.2 34.1 34.4 No No 

(a)

 Gas standard dilution system was not flushed before this span check was performed. (b)

 Data presented were for the average of five replicate challenges of zero air and 30 ppb H2S. 

30
 Span Drift Check Measurement Data Average Response Automated Span Check Results

 Dilution System Not Flushed Warning Limit Automated Zero Check Results

 Zero Drift Check Measurement Data Action Limit 

45 

40 

35 

30 

25 

20 

15

120 

110 

100 

90 

80 

70 

60 

Automated Span and Zero Checks H2S (ppb) 

Average Measured H2S (ppb) 

2 2 

0 0 

-2 -2 

-4 -4 

5/1/2005 5/11/2005 5/21/2005 5/31/2005 

Figure 6-5. Span and Zero Drift Control Chart 

Based on the data presented in Table 6-3 and Figure 6-5, drift in the Model 101E zero did occur 

during the verification test; zero drift is defined as three consecutive drift check results that fell 

outside of the warning limit of -0.1 ppb to +0.0 ppb established during the first week of the 

verification test. With the exception of one very low value (-4.8 ppb for Week 2, Saturday), the 

Model 101E response to zero increased during the verification test, but appeared to level off at 

Week 3. The results of the automated zero check appear to follow the same trend as the manual 

zero drift checks performed as a part of this verification test. The final zero span check result 

was 0.4 ppb greater than the average baseline zero response. 

The warning limit established for the Model 101E response to the 30-ppb H2S span gas was 34.7 

to 36.1 ppb. Drift in the Model 101E response to the 30-ppb H2S span gas did not occur during 

the verification test. The final span drift check result was 1.2 ppb less than the average baseline 

span response. 

6.6 Response Time 

Response time was determined during Week 1 and Week 4 from the amount of time required for 

the Model 101E to reach 95% of the change in response during the zero air and 30-ppb H2S span 

gas replicate deliveries shown in Figure 6-6. Table 6-5 presents a summary of the response time 

determinations for the Model 101E. The response time (both rise and fall, averaged for Week 1 

and Week 4) was 3 minutes. 

31
Model 101E Measurement Data Nominal Hydrogen Sulfide Concentration

H

ydrogen Sulfide (ppb) 

40 

30 

20 

10 

0 

40 

30 

20 

10 

0 

Week 1 

Week 4 

00:00 00:30 01:00 01:30 02:00 02:30 03:00 03:30 

Elapsed Time (hours) 

Figure 6-6. Model 101E Response Time Results 

6.7 Interference Effects 

The effect of potential interferant gases on the response of the Model 101E was assessed by 

supplying the Model 101E with a series of seven gases (listed in Table 6-6) in zero air and a 

100-ppb H2S standard. The response of the Model 101E during the introduction of these gases is 

summarized in Table 6-6. 

32
Table 6-5. Response Time Determinations 

Week 1 Week 4 

Replicate 0 ppb to 30 ppb 30 ppb to 0 ppb 0 ppb to 30 ppb 30 ppb to 0 ppb 

95% Rise Time Fall Time 95% Rise Time 95% Fall Time 

(minutes) (minutes) (minutes) (minutes) 

1 (a) 

2 4 (a) 

2 3 2 3 3 

3 3 3 4 3 

4 3 3 4 3 

5 3 4 4 3 

Average 3 3 4 3 

(a)

 The Week 1 sequence of zero/30-ppb H2S replicate challenges began with a 30-ppb H2S standard; the Week 4 

sequence began with zero air. 

Table 6-6. Interference Effect Evaluation 

Approximate Interference Effect (%) 

Interferant 

Interferant Concentration (ppb) Zero Air Matrix 100-ppb H2S Matrix 

Sulfur dioxide 100 0 0

Carbonyl sulfide 100 20 6

Carbon disulfide 100 6 9

Methyl mercaptan 100 33 33

Dimethyl sulfide 100 12 12

Hydrocarbon blend 500 (total) 0 0

Ammonia 500 0 0

No interference effect was observed in the Model 101E response to SO2, a blend of C1 to C6 

alkanes, and ammonia. The Model 101E showed an interference effect for carbonyl sulfide in 

zero air of 20% and in 100-ppb H2S of 6%. Carbon disulfide resulted in an interference effect of 

6% in zero air and 9% in the 100-ppb H2S matrix. The interference effect of methyl mercaptan 

on the Model 101E was 33% in both zero air and 100-ppb H2S. Dimethyl sulfide resulted in a 

12% interference effect in both matrices. 

33 
6.8 Comparability 

As stated previously, the Model 101E was calibrated with an H2S compressed gas cylinder that 

was independent of the standard used in the verification testing. The instrumentation for both 

reference methods was calibrated using the same gas standard used in the verification testing of 

the Model 101E. To reduce the potential impact on the comparability results due to differences 

in calibration gases, the Model 101E data were corrected using the results of the linearity checks 

(Section 6.4) closest in time to the reference sample collection date. Thus, both reference method 

and Model 101E calibrations were referenced to the same H2S gas standard for the comparability 

evaluations, and any differences observed between the Model 101E and reference method data 

can be attributed to the analytical approach rather than the calibration source. 

It should be noted that the reference method quality control requirements were not fully satisfied, 

and, therefore, the accuracy of the reference method results could not be verified. In addition, the 

swine finishing farm ambient air, which can contain high levels of ammonia and other small, 

polar molecules, was very challenging analytically and may have caused measurement artifacts 

resulting from contact of H2S and other gases with non-passivated surfaces in the air sampling 

system. The comparability results presented here should be considered cautiously in light of the 

reference method quality control results and the challenges associated with the complex ambient 

air matrix. 

6.8.1 Time-Integrated Comparability 

The results of 8 time-integrated reference method measurements were compared to the timeaveraged Model 101E responses over the same periods (approximately 7.5 to 8 hours, n=407 to 

498 data points) to determine the time-integrated comparability. One of these measurements was 

a grab sample, collected by allowing the canister to fill rapidly without a flow controller on the 

inlet (n=3). Six time-integrated reference method measurements were below the quantitation 

limit (2.2 ppb). An additional time-integrated measurement was performed, but the Model 101E 

data were not being logged to the Model 101E internal memory during that sample period. The 

maximum preanalytical holding time stated in the test/QA plan(1)

 was 24 hours; however, 

holding times exceeded 24 hours for 12 of the 15 time-integrated reference measurements. The 

long holding times may have resulted in degradation of H2S in the canisters. The reference 

method measurements were compared to the Model 101E data by linear regression analysis and 

by determining whether the measurements were significantly different at the 95% confidence 

level. 

Figure 6-7 shows the time-integrated reference H2S measurements (red and green traces), the 

Model 101E raw H2S data (blue trace), and the Model 101E averages for the reference 

measurement sample periods (black trace). As is evident in the figure by green traces for the 

reference measurements, the results for 5 of the 8 (63%) quantitative time-integrated reference 

measurements were not statistically significantly different from the Model 101E averages. (The 

grab sample is not shown and was not within the 95% CI of the Model 101E value.) The Model 

101E and time-integrated reference method data are presented in Appendix B. 

34
Hydrogen sulfide (ppb) 

100 

Model 101E Measurements:

 101E Measurement Data

 101E Averaged Data 

Time-integrated Reference Measurements:

80 Outside Model 101E 95% CI

 Within Model 101E 95% CI

 Quantitation Limit

 Canister sampling period 

60 

40 

20 

0 

06:00 12:00 00:00 06:00 

4/30/2005 5/5/2005 5/13/2005 5/21/2005 

Figure 6-7. Comparison of Time-Integrated Reference Measurements with Averages 

from the Model 101E 

A linear regression analysis of the Model 101E averages during the reference sampling periods 

versus the H2S concentration determined by the time-integrated reference method was 

calculated. The data are presented as a scatter plot in Figure 6-8 to illustrate the correlation 

between the reference results and the Model 101E data. The scatter plot includes reference 

method results that were within (green diamonds) and outside (red diamonds) the Model 101E 

95% CI. The slope of the regression line including all available quantitative results was 1.03 

(±1.10), with an intercept of -1.7 (± 31) and an r2

 value of 0.7807. When only the five results that 

were not significantly different at the 95% confidence level were included in the linear 

regression analysis, the slope was 0.22 (± 1.1), with an intercept of 4.7 (± 14) and an r2

 value of 

0.3673. 

6.8.2 In Situ Comparability 

The results of 41 in situ reference method results were compared to 15-minute averages (n=15) 

calculated from the Model 101E data that were centered in time on the in situ reference 

measurement times. The 95% CI was calculated for each Model 101E average and compared to 

the in situ reference measurement to determine if the results were significantly different at the 

95% confidence level. Figure 6-9 shows selected in situ reference measurements (red and green 

diamonds), the Model 101E H2S data, and the Model 101E 15-minute averages. Any upper and 

lower limits reported for the in situ reference method are also shown in Figure 6-9. As demonstrated by the green diamonds in Figure 6-9, 37% (15 of 41) of the quantitative in situ reference 

values were not significantly different from the corresponding Model 101E 15-minute averages. 

The Model 101E and in situ reference method data are presented in Appendix C. 

35
60 

50 

Average Model 101E Response (ppb) 40 

30 

20 

10 

0 

Results within 95% CI 

Results outside 95% CI 

1:1 Line 

All Results: 

y = 1.03x - 1.7 

r

2

 = 0.7807 

Results within 95% CI: 

y = 0.22x + 4.7 

r

2

 = 0.3673 

0 10 20 30 40 50 

Time-Integrated Hydrogen Sulfide Concentration (ppb) 

Figure 6-8. Scatter Plot of Model 101E Results versus Time-integrated Reference 

Measurements 

A linear regression analysis of the Model 101E averages during the reference sampling periods 

versus the H2S concentration determined by the in situ reference method is presented in 

Figure 6-10 as a scatter plot to illustrate the correlation between the reference results and the 

Model 101E data. The scatter plot includes reference method results that were within (green 

diamonds) and outside (red diamonds) the Model 101E 95% CI. The slope of the regression line 

including all available quantitative results was 0.16 (± 0.6), with an intercept of 26 (± 22) and an 

r

2

 value of 0.0313. When only the 15 results that were not significantly different at the 95% 

confidence level were included in the linear regression analysis, the slope was 1.06 (± 0.26), 

with an intercept of 2.2 (± 8.5) and an r2

 value of 0.9606. 

36

60 
Results within 95% CI: 

y = 1.06x + 2.2 

r

2

 = 0.9606 

All Results: 

y = 0.16x + 26 

r

2

 = 0.0313 

Results within 95% CI 

Results outside 95% CI 

1:1 Line 

Hydrogen Sulfide (ppb) 

350 

300 

250 

200 

150 

100 

50 

0 

Model 101E Measurements: 

Measurement Data

 15 Minute Average

 15 Minute Range 

In-situ Reference Measurements:

 Outside Model 101E 95% CI

 Within Model 101E 95% CI

 Upper Limit

 Lower Limit 

18:00 20:00 22:00 14:00 16:00 18:00 20:00 

6/1/2005 6/2/2005 

Figure 6-9. Comparison of Selected In Situ Reference Measurements with Model 101E 

Averages and Measurement Data 

90 

Average Model 101E Response (ppb) 80 

70 

60 

50 

40 

30 

20 

10 

0 

0 10 20 30 40 50 60 70 80 90 

In Situ Hydrogen Sulfide Concentration (ppb) 

Figure 6-10. Scatter Plot of Model 101E Results versus In Situ Reference 

Measurements 

37 
6.9 Data Completeness 

The Model 101E operated for 100% of the available time during the verification test; 88% of the 

available data were retrieved from the Model 101E, as discussed further in Section 6.10. The 

data loss is attributed to a glitch in the data download software or the on-board data acquisition 

parameters. 

6.10 Operational Factors 

The Model 101E was installed at the test site by the vendor representative, and installation was 

completed in less than one day. One calibration was performed on the Model 101E by USDA 

and Battelle staff prior to the start of the verification test and repeated after installation of a new 

UV lamp; no other calibrations were performed. The Model 101E could have been installed and 

operated by a user with minimal experience and access to the Model 101E manual, which was 

quite thorough. A checklist was provided by the vendor representatives to establish whether the 

Model 101E was in proper working order during the test. The checklist, shown in Appendix A, 

was completed by Battelle or USDA staff during daily checks of the Model 101E operating 

status. The inlet filter was changed once during the verification test; the filter change was 

completed in less than 15 minutes. The only other maintenance performed by Battelle or USDA 

was replacement of the UV lamp, which failed before the beginning of the verification test. A 

brief telephone call to Teledyne-API’s customer service support center diagnosed the problem 

quickly and a new lamp was received at the USDA laboratory the following day. Changing the 

lamp was simple and straightforward and took less than 30 minutes. The Model 101E was 

recalibrated approximately one day after the lamp installation. 

The Model 101E data were collected on a laptop computer provided by the USDA. The 

Teledyne-API proprietary software, APIcom was provided by the vendor representatives for use 

in downloading, viewing, saving, and graphing the Model 101E data. An ethernet router 

(provided by the vendor representatives) was used to connect the data output port to the laptop 

computer via an ethernet connection. Individual records could be downloaded individually (i.e., 

only H2S concentration data) or as combined files with additional parameters, such as detector 

values, Model 101E box temperature, etc. The Model 101E on-board memory stored 

approximately 7 days of data. Files containing 7 days of data for nine parameters were 

approximately 1 megabyte in size. 

Some difficulties were encountered with the data download process. On three occasions, more 

than 19 hours of data were lost. It was eventually discovered that the Model 101E stopped 

logging data after certain data download commands were employed (for download options 

“since last download” and “download all records”). The data logging could be restarted by 

scrolling through and resetting the data acquisition parameters from the Model 101E panel; 

curiously, none of the data acquisition parameters appeared to have changed as a result of this 

process. Teledyne-API customer support was contacted regarding the issue, but no problems 

were found in the Model 101E programs. Once the cause of the problem was determined, test 

operators were careful to confirm that the Model 101E was still logging data by downloading a 

few records to the laptop computer or by viewing the logged data from the Model 101E panel 

display after each data download. The APIcom software and router occasionally lost 

communication with the Model 101E, but this was relatively easily remedied by restarting the 

38
software or restarting the Model 101E and the laptop computer (to reset the Model 101E IP 

address). 

39
Chapter 7 

Performance Summary

The performance of the Model 101E was evaluated for its accuracy, bias, precision, linearity, 

span and zero drift, response time, interference effects, and comparability by evaluating the 

Model 101E response while sampling H2S and other gas standards at known concentrations and 

ambient air. The Model 101E was calibrated prior to this verification test with a 400-ppb dilution 

from an H2S gas standard (100 ppm H2S) that was independent of the gas standard (5.12 ppm 

H2S) used for performing the verification test. All gas standard dilutions were prepared using the 

same dynamic dilution system. The results of this evaluation are described below. 

The accuracy of the Model 101E was assessed over the range of 30 ppb to 300 ppb in terms of 

%R, which ranged from 114% to 132%, with an average of 129% for the Week 1 check. The 

Model 101E %R values for the Week 4 check ranged from 111% to 127%, with an average of 

124%. For the Week 5 check, the Model 101E %R values ranged from 113% to 122%, with an 

average of 120%. 

The Model 101E bias observed during the Weeks 1, 4, and Week 5 accuracy checks (30 ppb to 

300 ppb) was +29%, +24%, and +20%, respectively. The consistently high bias is indicative of 

systematic error, which would also affect the Model 101E accuracy, and could be caused by a 

number of factors, including, but not limited to, differences in H2S gas standards used for 

calibration and testing activities, the gas standard dilution system, and Model 101E instrumental 

errors. 

The precision of the Model 101E reading varied from 0.3% to 6.3% during the Week 1 accuracy 

check, from 0.9% to 4.8% during the Week 4 accuracy check, and from 0.4% to 2.7% during the 

Week 5 check. The average precision calculated from each check was 1.9%, 2.0%, and 1.2% for 

Weeks 1, 4, and 5, respectively. 

Linearity was evaluated in terms of slope, intercept, and r2

 over the range from 0 ppb to 300 ppb 

H2S. For Week 1, the slope of the regression line was 1.32 (± 0.02), with an intercept of -0.64 

(± 2.6) and r2

 value of 0.9999. During Week 4, the linear regression showed a slope of 1.25 

(± 0.02), an intercept -0.37 (± 3.5), and an r2

 of 0.9998. The linear regression analysis of the 

Week 5 data resulted in a slope of 1.20 (± 0.01), an intercept 0.24 (± 2.6), and an r2

 of 0.9999. 

Drift (defined as three consecutive drift check results that fell outside of the (±2 standard 

deviation) warning limit calculated for zero (-0.10 ppb to +0.0 ppb) and a 30-ppb span gas (34.7 

to 36.1 ppb). Eleven consecutive zero drift check results fell above the warning limit, indicating 

that drift occurred. The final zero drift check value was 0.4 ppb greater than the baseline 

40
response. Although four out of seven drift check results fell outside the warning limit, drift did 

not occur in the Model 101E response to the 30-ppb H2S span gas. The final span drift check 

value was 1.2 ppb lower than the baseline response. 

The average 95% response time was 3 minutes for both the rise time and fall time. 

No interference effect was observed in the Model 101E response to SO2, a blend of C1 to C6 

alkanes, and ammonia. The Model 101E showed an interference effect for carbonyl sulfide in 

zero air of 20% and in 100-ppb H2S of 6%. Carbon disulfide resulted in an interference effect of 

6% in zero air and 9% in the 100-ppb H2S matrix. The interference effect for methyl mercaptan 

was 33% in both zero air and 100-ppb H2S. Dimethyl sulfide resulted in a 12% interference 

effect in both matrices. 

Comparability was evaluated in terms of the slope, intercept, and r2

 of a linear regression 

analysis of the Model 101E averages versus the reference measurements and was calculated 

separately for the time-integrated and in situ reference methods. It should be noted that the 

reference method quality control requirements, such as for preanalytical holding time and 

analysis of quality control and performance evaluation standards, were not fully satisfied. 

Therefore, the accuracy of the reference method results could not be verified. In addition, the 

swine finishing farm ambient air, which can contain high levels of ammonia and other small, 

polar molecules, was very challenging analytically and may have caused measurement artifacts 

resulting from contact of H2S and other gases with non-passivated surfaces in the air sampling 

system. The comparability results presented here should be considered cautiously in light of the 

reference method quality control results and the challenges associated with the complex ambient 

air matrix. For the eight quantitative time-integrated reference measurements, the slope of the 

regression line was 1.03 (± 1.10), with an intercept of -1.7 (± 31) and an r2

 value of 0.7807. Five 

of the 8 (63%) time-integrated reference measurements were not significantly different from the 

corresponding Model 101E averages at the 95% confidence level. When only these five values 

were included in the linear regression analysis, the slope was 0.22 (± 1.1), with an intercept of 

4.7 (± 14) and an r2

 value of 0.3673. The regression line slope for 41 quantitative in situ 

reference measurements was 0.16 (± 0.6), with an intercept of 26 (± 22) and an r2

 value of 

0.0313. Fifteen of the 41 quantitative in situ reference values (37%) were not significantly 

different from the corresponding Model 101E 15-minute averages. The regression analysis of 

those 15 data points yielded a slope of 1.06 (± 0.26), an intercept of 2.2 (± 8.5), and an r2

 value 

of 0.9606. 

A user with minimal experience and the instruction manual could install and operate the Model 

101E. Daily checks of the Model 101E were simple and quick. Some difficulty was encountered 

in maintaining the ethernet connection between the laptop computer used for downloading data 

(using Teledyne-API's APICOM software), but it generally took less than 10 minutes to restore 

the connection. The Model 101E data logging was terminated when data were downloaded using 

certain commands, such as “download all records.” This resulted in loss of potential data. 

Teledyne-API customer support was contacted about this issue, but no cause could be 

determined. However, once the problem was identified, Battelle and USDA staff verified that 

data logging was occurring after each data download and were able to restore data logging if it 

had been terminated. Customer service telephone support was readily available and very helpful 

whenever contacted by Battelle or USDA staff. The only maintenance required during the 

41
verification test was one inlet filter change. A new UV lamp was installed prior to the start of the 

verification test; the installation was completed in less than 30 minutes. 

The Model 101E operated 100% of the time, and 88% of the data were retrieved. The loss of 

22% of the potential data was caused by the termination of data logging discussed above. 

42
Chapter 8 

References

1. Test/QA Plan for Verification of Ambient Hydrogen Sulfide Analyzers at a Swine Finishing 

Farm, Battelle, Columbus, Ohio, April 2005. 

2. ASTM International. Standard Test Method for Determination of Sulfur Compounds in 

Natural Gas and Gaseous Fuels by Gas Chromatography and Chemiluminescence. 

Designation: D5504-01, 2001. 

3. Quality Management Plan (QMP) for the ETV Advanced Monitoring Systems Center, 

Version 5.0, U.S. EPA Environmental Technology Verification Program, Battelle, 

Columbus, Ohio, March 2004. 

43

Appendix A

Model 101E Checklist

A-1
_____________________________________________________________________ 

_____________________________________________________________________ 

_____________________________________________________________________ 

Teledyne-API Model 101E 

ETV Verification of Ambient Hydrogen Sulfide Analyzers 

at a Swine Feeding Farm 

Observe Analyzer Front Panel 

9 Verify that power is on 

9 Check for alarms Alarm = ___________________ 

9 Visually inspect filter 

9 Clean 

9 Dirty (replace if dirty) 9 Replaced 

9 Download Data Download Time = ____________ 

9 Send data to Battelle (daily M-F) Most recent Date __________ 

9 Send data to Teledyne-API (at least weekly) Most recent Date __________ 

Action: If any of issues above fails, note in logbook and contact: 

(Vendor contact information) 

Operator Name: _______________________________________

Signature: ____________________________________________

Date: ____________________

Comments: ___________________________________________________________

Note: Please remember to sign and date this form in non-erasable ink. 

A-2
Appendix B

Model 101E and Time-Integrated Comparability Data

B-1
Start Date 

and Time 

4/29/05 

7:30 

4/29/05 

22:00 

4/30/05 

7:25 

Time-Integrated Reference Method 

Stop Date 

and Time 

Result 

(ppb) 

Distribution ln Result Holding time (hr) 

4/26/05 

15:0 

<2.2 lognormal NA 13 

4/30/05 

5:30 

6.0 lognormal 1.79 39 

4/30/05 

14:55 

<2.2 lognormal NA 28 

Final 

QCS

(a) (a) (a) 

Average 

Result 

(ppb) 

5.15 3.88 

(b) 

SD 

(ppb) 

9.62 2.91 

(b) 

Model 101E 

ln 

Average ln SD 

1.20 0.72 1.20 0.54 

(b) (b) 

n 

451 451 

(b) 

95

1.14 

1.15 

5/4/05 

21:45 

5/5/05 

11:00 

5/5/05 

5:15 

5/5/05 

18:30 

23.7 57.4 

lognormal 

normal 

3.17 

NA 

43 

33 

Pass 

Pass 

9.14 

53.19 

7.51 

16.55 

1.95 

(c) 

0.81 

(c) 

451 

451 

1.88 

51.67 - 

5/5/05 

21:45 

5/6/05 

5:15 

34.0 lognormal 3.53 23 Pass 55.29 13.91 3.98 0.24 451 3.96 

5/11/05 

21:45 

5/12/05 

5:52 

<2.2 lognormal NA 97 Fail 1.47 0.97 0.20 0.29 488 0.15 

5/12/05 

5:55 

5/12/05 

13:25 

<2.2 lognormal NA 88 Fail 7.10 7.78 1.69 0.62 447 1.63 

5/12/05 

14:00 

5/12/05 

22:00 

5.0 lognormal 1.61 75 Fail 5.73 14.27 1.27 0.77 498 1.20 

5/12/05 

22:00 

5/13/05 

6:00 

<2.2 lognormal NA 68 Fail 6.91 7.25 1.53 0.92 480 1.45 

5/13/05 

7:10 

5/18/05 

15:11 

5/19/05 

15:00 

5/20/05 

14:13 

5/13/05 

15:05 

5/18/05 

15:14 

5/19/05 

22:30 

5/20/05 

21:43 

10.6 34.3 

<2.2 

<2.2 

lognormal 

normal 

lognormal 

lognormal 

2.36 

NA 

NA 

NA 

50 

5 

46 

25 

Fail 

Pass 

(a) (a) 

10.74 

29.14 

5.73 1.50 

13.86 

0.10 

2.03 0.69 

1.86 

(c) 

1.70 0.32 

0.88 

(c) 

0.30 0.42 

470 

3 

408 407 

1.78 

28.90 - 

1.67 0.27 

5/21/05 

10:05 

5/21/05 

17:35 

9.5 lognormal 2.25 44 Fail 6.33 7.31 1.45 0.82 447 1.37 

B-2

ln = natural logarithm (a) No final QCS data provided. (b) Model 101E data not logged by internal memory during this sample. (c) Model 101E data were normally distributed, so the natural logarithm was not calculated. 
Appendix C

Model 101E and In Situ Comparability Data

C-1
In situ Reference Method Model 101E (ppb) Reference 

Result at Result 

Sample Result Final Sample Average Within 

Midpoint (ppb) QCS Midpoint Result SD 95% CI 95% CI? 

5/30/05 14:04 1.51 42.18 14.24 21.24 1.97 - 26.50 No 

5/30/05 14:20 <1.48 1.93 2.57 0.86 2.10 - 3.04 NA 

5/30/05 14:36 <1.48 4.68 2.80 1.64 1.89 - 3.70 NA 

5/30/05 15:26 2.69 4.14 3.71 2.05 2.57 - 4.85 Yes 

Pass 

5/30/05 15:49 <1.78 

5/30/05 19:08 <1.48 

4.53 

0.60 

2.76 1.32 

0.57 0.22 

2.03 - 3.50 

0.45 - 0.70 

NA 

NA 

5/30/05 19:24 <1.48 1.80 1.39 1.06 0.80 1.97 NA 

5/30/05 21:42 12.79 196.72 155.68 86.62 107.71 - 203.66 No 

5/30/05 21:56 168.62 1.19 2.60 3.48 0.67 - 4.52 No 

5/30/05 22:12 2.95 4.35 2.82 1.25 2.13 - 3.51 Yes 

5/31/05 11:20 0.38 0.69 0.42 0.22 0.30 0.54 Yes 

(a) 5/31/05 11:48 0.37 1.14 1.12 0.37 0.91 - 1.32 No 

5/31/05 22:17 2.96 -0.04 0.04 0.07 0.01 - 0.08 No 

6/1/05 17:55 10.21 13.28 25.99 14.15 18.15 - 33.82 No 

6/1/05 18:02 19.28 35.79 27.97 11.38 21.66 - 34.27 No 

6/1/05 18:20 >42.49 91.90 45.45 28.69 29.56 - 61.34 NA 

6/1/05 18:35 17.05 58.21 18.40 16.33 9.35 - 27.44 Yes 

6/1/05 19:05 3.37 2.20 16.33 14.73 8.17 - 24.49 No 

6/1/05 19:21 14.59 23.84 19.28 8.14 14.77 - 23.79 No 

6/1/05 19:42 5.04 17.25 29.71 14.68 21.58 - 37.84 No 

(a) 6/1/05 20:03 35.18 42.82 63.70 32.15 45.90 - 81.51 No 

6/1/05 20:24 >42.85 89.75 113.04 26.30 98.47 - 127.61 NA 

6/1/05 20:45 >42.85 146.08 150.83 42.35 127.38 - 174.29 NA 

6/1/05 21:05 >42.85 251.48 197.34 83.40 151.15 - 243.53 NA 

6/1/05 21:26 >42.85 177.01 140.52 58.50 108.12 - 172.92 NA 

6/1/05 21:56 3.09 2.04 2.24 0.70 1.85 - 2.63 No 

6/1/05 22:43 0.44 0.36 0.45 0.24 0.31 - 0.58 Yes 

6/1/05 23:16 1.85 1.74 1.06 0.54 0.73 - 1.37 No 

6/2/05 11:53 59.55 51.85 36.29 24.27 22.85 - 49.73 No 

6/2/05 12:08 9.40 4.88 34.30 31.13 17.06 - 51.54 No 

6/2/05 12:25 60.56 69.88 64.24 30.20 47.51 - 80.96 Yes 

6/2/05 12:46 7.83 1.13 22.42 25.92 8.06 - 36.78 No 

6/2/05 13:08 45.65 97.29 55.77 36.33 35.65 - 75.89 Yes 

6/2/05 13:23 41.57 70.48 47.08 18.59 36.79 - 57.38 Yes 

6/2/05 13:39 46.60 Pass 77.87 20.63 21.12 8.94 - 32.33 No 

6/2/05 13:55 88.07 101.18 41.79 47.62 15.42 - 68.17 No 

6/2/05 14:11 7.99 4.48 30.36 28.47 14.59 - 46.13 No 

6/2/05 16:06 7.83 50.79 15.28 13.62 7.74 - 22.82 Yes 

6/2/05 16:22 47.66 40.22 40.21 21.91 28.08 - 52.35 Yes 

6/2/05 16:38 <7.69 7.50 6.15 3.59 4.16 - 8.14 NA 

6/2/05 16:54 7.80 8.70 8.08 5.55 5.00 - 11.15 Yes 

6/2/05 17:11 8.32 107.99 43.11 35.44 23.48 - 62.74 No 

C-2
In situ Reference Method Model 101E (ppb) Reference 

Sample 

Midpoint 

Result 

(ppb) 

Final 

QCS 

Result at 

Sample 

Midpoint 

Average 

Result SD 95% CI 

Result 

Within 

95% CI? 

6/2/05 17:28 8.70 10.39 51.90 34.87 32.59 - 71.21 No 

6/2/05 17:44 39.82 31.04 51.08 26.39 36.47 - 65.70 Yes 

6/2/05 18:00 13.12 49.37 48.38 20.66 36.94 - 59.82 No 

6/2/05 18:16 62.63 86.63 68.35 20.83 56.81 - 79.89 Yes 

6/2/05 18:31 18.32 Pass 30.98 43.62 22.55 31.13 - 56.11 No 

6/2/05 19:05 18.01 7.61 26.89 25.11 12.98 - 40.80 Yes 

6/2/05 19:20 45.34 27.28 29.17 8.36 24.54 - 33.80 No 

6/2/05 19:35 7.87 9.98 30.88 16.99 21.47 - 40.29 No 

6/2/05 19:51 21.67 18.13 27.83 13.28 20.48 - 35.19 Yes 

6/3/05 4:33 1.56 (a) 0.81 0.88 0.22 0.74 - 1.00 No 

(a)

 QCS not analyzed at end of sampling on this date because the liquid nitrogen supply ran out. 

C-3