July 2004
Environmental Technology
Verification Report
Omnisens
TGA310 Ammonia Analyzer
Prepared by
Battelle
Baireiie
itte li usincss of Innovation
In collaboration with the
U.S. Department of Agriculture
Under a cooperative agreement with
SEPA U.S. Environmental Protection Agency
ETV ExV ElV
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July 2004
Environmental Technology Verification
Report
ETV Advanced Monitoring Systems Center
Omnisens
TGA310 Ammonia Analyzer
by
Ken Cowen
Ann Louise Sumner
Amy Dindal
Karen Riggs
Zack Willenberg
Battelle
Columbus, Ohio 43201
and
Jerry Hatfield
Richard Pfieffer
Kenwood Scoggin
USDA National Soil Tilth Laboratory
Ames, Iowa 50011
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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.
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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 seven environmental technology 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/center 1. html.
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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
Ernie Bouffard, Connecticut Department of Environmental Protection; Rudy Eden, South Coast
Air Quality Management District; Roy Owens, Owens Corning; and Jim Homolya, Bruce Harris,
and Linda Sheldon, U.S. Environmental Protection Agency, for their careful review of the
verification test/QA plan and this verification report. We also thank Amy Morrow and Diane
Farris of the U.S. Department of Agriculture National Soil Tilth Laboratory for their assistance
in performing the reference sample analysis.
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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 Test Design 3
3.2 Site Description—Phase II 4
3.3 Test Procedures 5
3.3.1 Accuracy, Linearity, Precision, and Response Time 5
3.3.2 Calibration and Zero Drift 5
3.3.3 Interference Effects 5
3.3.4 Comparability 6
4 Quality Assurance/Quality Control 8
4.1 Equipment Calibrations 8
4.1.1 Reference Method Sampling Equipment 8
4.1.2 Analytical Equipment 8
4.1.3 Meteorological Equipment 9
4.1.4 Ammonia Dilution System 9
4.2 QC Samples 9
4.2.1 Field Blanks 9
4.2.2 Denuder Breakthrough Checks 10
4.2.3 Duplicate Samples 12
4.2.4 Laboratory Blanks 12
4.2.5 Calibration Checks 13
4.2.6 Gas Standard Dilution Checks 13
4.3 Audits 14
4.3.1 Performance Evaluation Audit 14
4.3.2 Technical Systems Audit 15
4.3.3 Audit of Data Quality 15
4.4 QA/QC Reporting 15
4.5 Data Review 16
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5 Statistical Methods and Reported Parameters 17
5.1 Relative Accuracy 17
5.2 Linearity 17
5.3 Precision 17
5.4 Response Time 18
5.5 Calibration and Zero Drift 18
5.6 Interference Effects 18
5.7 Comparability 18
6 Test Results 19
6.1 Relative Accuracy 19
6.2 Linearity 22
6.3 Precision 22
6.4 Response Time 23
6.5 Calibration and Zero Drift 23
6.6 Interference Effects 24
6.7 Comparability 25
6.8 Ease of Use 26
6.9 Data Completeness 28
7 Performance Summary 29
8 References 31
Appendix A. TGA310 Checklist A-2
Figures
Figure 2-1. TGA310 Ammonia Analyzer 2
Figure 3-1. Phase II Test Site 4
Figure 3-2. Reference Method Sampling Cartridge 6
Figure 4-1. Denuder Breakthrough During Phase II as a Function of
Integrated Ammonia Concentration 11
Figure 4-2. Analysis of Diluted Ammonia Standards Using the Denuder Reference
Method 14
Figure 6-1. Phase II Meteorological Conditions and TGA310 Ambient NH3 Measurements 20
Figure 6-2. Phase II Accuracy Results for the TGA310 21
Figure 6-3. Results of Linearity Check of the TGA310 During Phase II 22
Figure 6-4. Comparison of Ambient Reference Measurements with Averages from
the TGA310 During Phase II 25
Figure 6-5. Scatter Plot of the TGA310 Results versus Ambient Reference
Measurements During Phase II 26
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Tables
Table 4-1. Minimum Detectable Ambient NH3 Concentrations During Phase II 10
Table 4-2. Denuder Breakthrough Checks During Phase II 12
Table 4-3. Duplicate Sampling During Phase II 13
Table 4-4. Data Recording Process 16
Table 6-1. Relative Accuracy Results 21
Table 6-2. Calculated Precision of the TGA310 23
Table 6-3. Response Time Determinations 23
Table 6-4. Calibration and Zero Checks During Phase II 24
Table 6-5. Interference Effect Evaluation 25
Table 6-6. Activities Performed During Phase II 27
Table 7-1. Performance Summary of the TGA310 30
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List of Abbreviations
AFO
animal feeding operation
AMS
Advanced Monitoring Systems
CI
confidence interval
DL
detection limit
EPA
U.S. Environmental Protection Agency
ETV
Environmental Technology Verification
FIA
flow injection analysis/analyzer
kg
kilogram
L
liter
Lpm
liters per minute
Hg
microgram
|j,m
micrometer
mg
milligram
mL
milliliter
mm
millimeter
NIST
National Institute of Standards and Technology
nh3
ammonia
nh4
ammonium
PC
personal computer
ppb
part per billion
%D
percent difference
QA
quality assurance
QC
quality control
QMP
quality management plan
RA
relative accuracy
RPD
relative percent difference
RSD
relative standard deviation
SD
standard deviation
TSA
technical systems audit
USD A
U.S. Department of Agriculture
viii
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Chapter 1
Background
The U.S. Environmental Protection Agency (EPA) supports the Environmental Technology
Verification (ETV) Program to facilitate the deployment of innovative environmental tech-
nologies 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 high-
quality, 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 tech-
nologies 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 peer-
reviewed 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) National Soil Tilth
Laboratory, recently evaluated the performance of the Omnisens TGA300 Series Model TGA310
ammonia (NH3) analyzer.
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Chapter 2
Technology Description
The objective of the ETV AMS Center is to verify the performance characteristics of environ-
mental monitoring technologies for air, water, and soil. This verification report provides results
for the verification testing of the TGA310. The following is a description of the TGA310, based
on information provided by the vendor. The information provided below was not subjected to
verification in this test.
The TGA310 (Figure 2-1) is a trace gas analyzer that uses photoacoustic spectroscopy to
measure ammonia concentrations in the atmosphere. In photoacoustic spectroscopy, absorbed
infrared (IR) energy generates a temperature increase and an associated pressure increase,
resulting in an acoustic wave that can be detected with a microphone. Sound intensity is directly
proportional to the gas concentration. The amount of absorbed energy is determined by
measuring the photoacoustic signal. In the TGA310, the light from a modulated carbon dioxide
laser, with a wavelength coinciding with the wavelength of ammonia, travels through a
photoacoustic sensing cell, through which ambient ammonia is continuously sampled.
The TGA310 has a 0.1-part-per-billion detection limit and allows real-time continuous
detection. Monitoring is possible at air flow rates up to 5 liters per minute (Lpm). The TGA310
features a graphical user interface. A built-in personal computer (PC) incorporates a touch-
screen display, and the measured ammonia concentration is highlighted on a real-time basis. The
evolution of ammonia concentration is displayed on a chart and can be checked at any time for
long-term trends analysis. The user gets an immediate view
of the trend by checking the displayed concentration
curves.
Measurement data are automatically stored in a designated
file, allowing unattended measurements. Historical data can
be retrieved remotely from the disk for data analysis.
Calibration data are stored on the built-in disk drive, and
default values can be retrieved at any time. Events such as
run up and run down times, alarms, system messages, and
setup modifications are stored in a log file.
The TGA310 requires 600 Watts of power from 110/230
Figure 2-1. TGA310 Ammonia volts alternating current. Its dimensions are 600 millimeters
Analyzer (mm) by 600 mm by 210 mm, excluding the PC, and it
weighs less than 70 kilograms. The TGA310 costs $42,000.
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Chapter 3
Test Design and Procedures
3.1 Test Design
Livestock agriculture is thought to be the primary source of atmospheric NH3 in the United
States and accounts for approximately 70% of NH3 emissions in the United States.(1) As a result,
a means to accurately quantify these emissions is needed. The objective of this verification test
was to verify the TGA310's performance in measuring gaseous NH3 in ambient air at animal
feeding operations (AFOs).
This verification test was conducted according to procedures specified in the Test/QA Plan for
Verification of Ambient Ammonia Monitors at Animal Feeding Operations,(2) with the exception
of six deviations that are addressed later in this report. The verification test was conducted in
two phases, each at separate AFOs. The first phase of testing was conducted between September
8 and October 3, 2003, at a swine finishing farm near Ames, Iowa. The second phase was con-
ducted between October 20 and November 14, 2003, at a cattle feedlot in Carroll, Iowa. These
sites were selected to provide realistic testing conditions, which were expected to exhibit a wide
range of NH3 concentrations during the test periods.
The verification test was designed to evaluate the following performance parameters:
¦ Relative accuracy
¦ Linearity
¦ Precision
¦ Response time
¦ Calibration/zero drift
¦ Interference effects
¦ Comparability
¦ Ease of use
¦ Data completeness.
The TGA310 was not available during Phase I of the verification test. However, during Phase II
of the verification test, the TGA310 response to a series of NH3 gas standards of known con-
centration was used to quantify relative accuracy (RA), linearity, precision (repeatability), and
calibration/zero drift. The TGA310 response time, the time to reach 95% of the stable signal,
was also assessed during the delivery of the NH3 standards. During Phase n, interference effects
were quantified from the TGA310 response to various chemical species that may be present at
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AFOs; the potential interferent gases were delivered both in the presence and absence of NH3.
The TGA310 response to ambient air was also evaluated during Phase II as the comparability to
simultaneous determinations by an ambient NH3 reference method (acid-coated denuders).
Additionally, the ease of use of the TGA310 was evaluated based on operator observations. Data
completeness was determined based on the amount of data collected as a percentage of the
amount of data that could have been collected.
3.2 Site Description—Phase II
During Phase n, the TGA310 was installed by a vendor representative. Battelle and USD A staff
worked with the vendor representative to establish procedures for operating the TGA310 during
this verification test. The vendor representative trained Battelle and USDA staff to check several
instrument parameters to verify the operation of the TGA310 and identify signs of malfunction,
which was done on a daily basis. A checklist, provided by the vendor representative and
included as Appendix A, was completed by Battelle and USDA staff during daily monitor
checks. In the event of an instrument malfunction, Battelle and/or USDA staff could contact the
vendor representative and conduct minor troubleshooting procedures upon request as necessary,
but were not expected to make any major repairs. The vendor representative remained on-site
until the installation was complete. All the testing activities were conducted by Battelle and
USDA staff.
Figure 3-1 shows a schematic diagram of the
cattle feedlot during Phase II of the verification
test. A temperature-regulated instrument trailer
was used to house the monitoring equipment and
to provide a sheltered workspace. The TGA310
was installed in this instrument trailer with a
Teflon sample line used to supply outside air to
the inlet of the TGA310. Outside the trailer, the
inlet of the sample line was positioned
approximately 1.5 meters from ground level. The
instrument trailer was in a harvested corn field
surrounded on three sides by cow pens. The farm
was surrounded on all sides by corn fields, most
of which had been harvested. Approximately
2,000 to 3,000 head of cattle were on the farm
during the verification test.
Trailer
Gravel drive
1*
rrT
Figure 3-1. Phase II Test Site
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3.3 Test Procedures
3.3.1 Accuracy, Linearity, Precision, and Response Time
During the first week of Phase n, the TGA310 was independently supplied with compressed
NH3 gas standards to achieve NH3 concentrations over a range from 0 to 2,000 parts per billion
(ppb) to simulate the approximate range expected in ambient air during Phase n. The gases
delivered to the TGA310 were prepared by diluting higher-concentration NH3 standard gases
(i.e., 100 to 500 parts per million) in zero air using a calibrated dilution system provided by the
USD A.
The NH3 gas was supplied to the TGA310 for approximately 30 minutes at each concentration
level. Accuracy, linearity, and precision were established based on the continuous digital data
set recorded by the TGA310 during the periods when the NH3 gas was supplied. Data were used
for the calculations once the signal had stabilized at a constant concentration (i.e., the signal did
not appear to be increasing or decreasing with time). The time required to reach 95% of the
stable reading for each concentration was also recorded for the TGA310. These data were used
to assess the response time of the TGA310.
3.3.2 Calibration and Zero Drift
On Tuesday, Wednesday, and Friday of the first week of testing, and Monday, Wednesday, and
Friday of the last week of testing during Phase n, the TGA310 was supplied with an NH3 gas
standard at nominally 1,000 ppb and zero air to check the calibration and zero drift of the
TGA310, respectively. Zero air and the 1,000-ppb NH3 standard were each supplied to the
TGA310 for approximately one hour, during which time the measured concentrations were
recorded by the TGA310.
3.3.3 Interference Effects
Once during Phase n, the TGA310 was independently supplied with a series of potential
interference gases (hydrogen sulfide, nitrogen dioxide, 1,3-butadiene, and diethylamine) to
assess any impact the gases have on the TGA310 response. The interferent gases were supplied
from diffusion tubes (VICI Metronics, Poulsbo, Washington) at concentrations of approximately
150 to 460 ppb in zero air and a 500-ppb NH3 standard as carrier gases.
The process for supplying the interferent gases was as follows: zero air was supplied to the
TGA310 until a stable reading was achieved. The interferent gas was added to the zero air flow
and supplied to the TGA310 until a stable reading was observed (at least two minutes). The
TGA310 was flushed for at least two minutes with zero air, and the next interferent gas was
delivered. This process was repeated for the four interferent gases. A 500-ppb NH3 standard was
then supplied to the TGA310 until a stable reading was achieved. The interferent gas was added
to the NH3 standard for delivery to the TGA310, and the process outlined above was repeated,
delivering the 500-ppb NH3 standard for at least 2 minutes between each interferent gas.
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3.3.4 Comparability
The comparability of the TGA310 with a standard reference method was established by
comparing the average TGA310 readings with time-integrated NH3 samples collected using
citric-acid-coated denuders. The reference samples were collected based on procedures
described in the EPA Compendium Method 10-
4.2, Determination of Reactive Acidic and Basic
Gases and Acidity of Fine Particles (<2.5 jnm).(i)
For this test, NH3 samples were collected using a
ChemComb Model 3500 Speciation Sampling
Cartridge (Rupprecht & Patashnick Co., East
Greenbush, New York). Figure 3-2 shows a
schematic illustration of the ChemComb sampling
cartridge. Samples were collected by drawing
ambient air through an impactor at a nominal rate
of 10 Lpm to remove particulate matter with
aerodynamic diameters greater than 2.5 micro-
meters (|im). The air was passed through two or
more citric-acid-coated denuders to collect
gaseous NH3. A single Teflon filter was used to
collect the particulate matter that passed through
the denuder. During Phase n, automated Parti sol
Model 2300 speciation samplers (Rupprecht &
Patashnick Co., East Greenbush, New York) were
used. The Partisol samplers were equipped with
mass-flow controlled sampling systems that were
pressure- and temperature-corrected.
The procedures that were used for preparing and
coating the denuders were based on the procedures
given in the ChemComb Operating Manual(4) and the test/QA plan(2). The denuders were coated
in an NH3-free glove box at a USDA National Soil Tilth Laboratory facility in Ames, Iowa, and
stored in an NH3-free glove box until they were installed in the ChemComb sampling cartridge
and transported to the test site. Cartridges were assembled in the laboratory and transported to
the test site. All denuders were used within 72 hours of being coated and within 24 hours of
being transported to the field.
Reference samples were collected during the second and third weeks of testing during Phase n.
To capture diurnal variations in NH3 concentrations, sampling was conducted on the following
schedule: 8:00 a.m. to 12:00 p.m., 12:00 p.m. to 2:00 p.m., 2:00 p.m. to 4:00 p.m., 4:00 p.m. to
8:00 p.m., and 8:00 p.m. to 8:00 a.m., so that five sets of samples were collected in each 24-hour
period. The short-term (two-hour and four-hour) sampling captured the midday peaks in NH3
concentrations, whereas the 12-hour sampling captured overnight, generally low, concentrations.
The ChemComb sampling cartridges for a full day of sampling were installed in the Partisol
speciation samplers before the first sampling period. The Partisol samplers automatically
To Pump
J,
I
t
Teflon filter
Denuder
Coating: 1% citric acid
Impactor
i r
Inlet
Figure 3-2. Reference Method Sampling
Cartridge
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switched the ambient air flow to each cartridge according to the schedule defined above. As a
result, the ChemComb samplers were exposed to the ambient environment for approximately
24 hours. After the final sampling period, all of the sampling media were retrieved and
transported to the USDA laboratory for extraction and analysis. Reference sampling for single-
point monitors was conducted at one location near the monitor inlets at the instrument trailer.
Duplicate samples were also obtained at this site. Two additional sampling locations were
positioned approximately 44 and 74 meters from the instrument trailer for use in the verification
testing of open-path monitors, but duplicate samples could not be obtained at these locations due
to limitations of the Partisol samplers. The sampling schedule for Phase II deviated from the
test/QA plan in that sampling was conducted every other day, including weekends, during the
two-week sampling period. The schedule allowed sufficient time for sample transportation and
processing between sampling days. The test/QA plan called for sampling every day, Monday
through Friday, during the sampling period.
Extraction and analysis of the denuders were performed as described in the test/QA plan,(2) with
one exception. The water volume used to extract the denuders was increased from 10 milliliters
(mL), as specified in the test/QA plan, to 20 mL. The volume was increased to accommodate the
sample volume requirements of the analysis method described below. A deviation was filed to
address this change, which does not impact the quality of the reference data. Samples were
extracted in an NH3-free glove box and stored in acid-washed scintillation vials to prevent
contamination. The samples were analyzed by USDA by flow injection analysis (FIA) using a
Lachat QuikChem Automated Flow Injection Ion Analyzer (Lachat Company, Loveland,
Colorado) according to QuikChem Method No. 10-107-06-2-A. This method involves heating
the NH3 sample with salicylate and hypochlorite in an alkaline phosphate buffer, which
produces an emerald green color proportional to the NH3 concentration. The color was
intensified by adding sodium nitroprusside and monitored photometrically.
When possible, samples were analyzed within 24 hours of extraction, as specified in the test/QA
plan. When analysis within 24 hours of extraction was not possible, the samples were stored
frozen until the analysis could be performed, in accordance with the test/QA plan.
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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(5) and the test/QA plan for this verification test.(2)
Six deviation reports were filed during this test and have been addressed in this report. In
summary, a change was made in the reference sampling schedule and equipment for Phase II
(Section 3.3.4), the denuder extraction volume was increased (Section 3.3.4), some percent
difference values measured for duplicate reference samples exceeded 10% (Section 4.2.3),
laboratory blank thresholds were redefined (Section 4.2.4), the order in which laboratory blanks
and calibration check standards were submitted for analysis was changed (Section 4.2.4 and
4.2.5), and not all of the test data were reviewed within two weeks of the end of the test phase
(Section 4.5). None of these deviations have impacted the quality of this verification test.
4.1 Equipment Calibrations
4.1.1 Reference Method Sampling Equipment
Reference method sampling was conducted based on the procedures described in the EPA
method(3) and the ChemComb operating manual.(4) A single-point calibration of the flow rate
through each of the sampling systems (i.e., pump, flow controller, filter pack, denuder,
impactor) was performed prior to starting Phase II using a flow meter with a National Institute of
Standards and Technology (NIST)-traceable calibration. For Phase n, flows were controlled by
the pressure- and temperature-corrected mass flow controllers used in the USDA's Partisol
samplers. These samplers shut off automatically if the flow deviated by ± 5% from the 10 Lpm
setpoint for more than 5 minutes, and the data were flagged. Actual sample volumes were
recorded by the samplers.
4.1.2 Analytical Equipment
The reference samples were analyzed in the USD A laboratory using FLA. A five-point
calibration was measured on the FLA for the reference sample analysis prior to each analytical
session by the USDA staff performing the analysis. The calibration was conducted according to
the manufacturer's recommendations and included concentrations of NH3 standard solutions
throughout the operating range of the FLA. The calibration was acceptable if the coefficient of
determination (r2) of the calibration curve was greater than 0.99. The FLA detection limit (DL)
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was 0.03 milligrams per liter (mg/L) and was determined as three times the standard deviation of
repeated measurements of a low-level NH3 standard. Any analytical results that fell below the
FIA DL were used without any further adjustment.
Calibration check standards were analyzed after every fifteenth sample in the batch. These
calibration checks were considered acceptable if the measured concentration agreed within 10%
of the standard solution concentration. If a calibration check failed to agree within 10% of the
standard concentration, the FIA was recalibrated; and all analyses since the last acceptable
calibration check were repeated. All calibration results were documented for inclusion in the
verification test data files.
4.1.3 Meteorological Equipment
The sensors used for meteorological monitoring had been calibrated by the manufacturer (Met
One Instruments, Inc., Grants Pass, Oregon) within one year of their use in this verification test.
The calibration results were included in the verification test data files.
4.1.4 Ammonia Dilution System
The USDANH3 dilution system (Environics, Tolland, Connecticut) employs three heated mass
flow controllers and valves dedicated for the dilution of compressed NH3 mixtures. The output
flow rates were verified using an independent, NIST-traceable flow meter and agreed to within
10%.
4.2 QC Samples
4.2.1 Field Blanks
At least 10%) of all reference samples collected were field blanks. The field blanks were collected
by installing the sampling media (i.e., denuder and filters) in the sampling train without drawing
any air through the train. The media were recovered and handled as normal samples. Field
blanks were collected at each of the sampling locations and during each of the sampling periods
(e.g., 8:00 a.m. to 12:00 p.m.). Field blank results were used to detect potential sample
contamination, (defined in the test/QA plan as field blank values greater than 5% of any
reference samples for that day) and also to determine the reference method DL.
The reference method DL was determined from the field blank results and reported in terms of
an NH3 mass corresponding to three times the standard deviation of the NH3 mass collected on
the field blanks. The reference method DL was more than six times higher than the equivalent
FIA DL (0.6 microgram [|ig] NH3 per 20-mL sample).
The reference method DL, reported as an NH3 mass, was used to determine the minimum
detectable NH3 concentrations for Phase n. Since the mass of NH3 collected by the reference
method is a function of the sampling time, flow rate, and the ambient NH3 concentration, the
minimum (time-integrated) ambient NH3 concentration detectable by the reference method
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varies depending on the sample period duration. (This assumes a constant flow rate.) For
example, to collect 100 |ig NH3, the time-integrated ambient NH3 concentration must be 20 ppb
for a 12-hour sample and 120 ppb for a two-hour sample. Accordingly, the minimum ambient
NH3 concentrations that could be detected from the collection of 2-, 4-, and 12-hour samples at a
nominal flow rate of 10 Lpm were calculated from the reference method DL for Phase n.
A total of 14 field blanks were collected in Phase n. The average NH3 mass collected on these
blanks was 2.5 |ig NH3, and the range was 0.5 to 4.6 |ig NH3. The mass collected on the field
blanks ranged from 1.2% to 55.0% of the smallest reference sample mass collected on the same
day, with an average of 19.2%. These percentages are not indicative of unusually high levels of
contamination, but rather are a result of relatively low ambient NH3 levels at the AFO. The
impact of these blank levels on the results of this verification test may be manifested as a small
positive bias of the reference method results relative to the readings of the technologies being
verified. This bias would be most pronounced on days with low ambient NH3 concentrations.
The highest field blank percentages were measured on days when the integrated ambient NH3
levels were as low as 6 ppb, which is approaching the 4.9-ppb minimum detectable ambient NH3
concentration for a two-hour sample. Assuming an ambient air sample volume of 1.2 cubic
meters, the smallest volume collected during Phase n, the maximum field blank value corre-
sponds to an ambient concentration of 5.5 ppb. Thus, the sample handling may account for up to
5.5 ppb of the measured values.
The standard deviation of the NH3 collected from field blanks for Phase II was 1.4 |ig, which
resulted in a 6.6 |j,g NH3 Phase II reference method DL. The minimum detectable ambient NH3
concentrations for 2-, 4-, and 12-hour samples (at a nominal flow rate of 10 Lpm) are shown in
Table 4-1. During Phase n, one measured NH3 concentration in ambient air fell below the
minimum detectable NH3 concentration, as summarized in Table 4-1.
Table 4-1. Minimum Detectable Ambient NH3 Concentrations During Phase II
2-Hour
4-Hour
12-Hour
Sample
Sample
Sample
Minimum detectable NH3 concentration
7.9 ppb
4.0 ppb
1.3 ppb
Number of reference samples collected
56
56
29
Number less than minimum detectable NH3
2
0
0
concentration
4.2.2 Denuder Breakthrough Checks
Use of backup denuders is called for in the test/QA plan during periods when breakthrough
greater than 10% of the front denuder is observed or expected. These backup denuders were
used to check the degree of NH3 breakthrough. The breakthrough checks were conducted at each
of the sampling locations and included checks during each of the five sampling periods (i.e.,
8:00 p.m. to 8:00 a.m., 8:00 a.m. to 12:00 p.m., etc.). Figure 4-1 shows the percentage of NH3
10
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240 -
220 -
60
40
20 -
V
~V^ ~
~ -~
~ 2 Hour Denuder 2
0 2 Hour Denuder 3
4 Hour Denuder 2
4 Hour Denuder 3
¦ 12 Hour Denuder 2
~ 12 Hour Denuder 3
of _
—I ~T
50 100 150 200 250
Integrated Ammonia Concentration (ppb)
300
350
Figure 4-1. Denuder Breakthrough During Phase II as a Function of Integrated
Ammonia Concentration
collected on the backup denuders relative to the front denuder (i.e., breakthrough) as a function
of the average NH3 concentration for each of the sampling period lengths (combined data from
both sampling locations). The solid symbols in this figure represent the first backup denuder
(identified as Denuder 2 in the legend), and the open symbols represent the second backup
denuder (identified as Denuder 3 in the legend). Data for all three Phase II sampling locations
are included here.
In general, breakthrough onto the first backup denuder (Denuder 2 in the figure legend) was low,
with an average breakthrough of 8.6%. As shown in the figure, many of the high breakthrough
values (i.e., greater than 10%) observed on the first backup denuder occurred at very low NH3
concentrations where the mass of NH3 collected was similar to that collected for field blanks.
The high values do not indicate that breakthrough occurred, but rather that the measurements
were near the DL of the reference method. High breakthrough of the first backup denuder also
occurred at higher NH3 concentrations and/or long sample durations. Although these high
breakthrough values may indicate that breakthrough of the first backup denuder occurred, the
second backup denuder (Denuder 3 in the figure legend) was in place to collect the remaining
NH3. With the exception of one sample that occurred at a low ambient NH3 concentration,
breakthrough observed on the second backup denuder was always less than 10% of the amount
collected on the front denuder. Thus, it is unlikely that NH3 was lost as a result of breakthrough
of the first or second backup denuders. Table 4-2 summarizes the results of the breakthrough
checks for Phase n.
11
-------
Table 4-2. Denuder Breakthrough Checks During Phase II
2-Hour Samples
4-Hour Samples
12-Hour Samples
1st Backup
Denuder
(%)
2nd Backup
Denuder
(%)
1st Backup
Denuder
(%)
2nd Backup
Denuder
(%)
1st Backup
Denuder
(%)
2nd Backup
Denuder
(%)
Percent of reference
samples with denuder
100
18
100
18
100
24
Average concentration as
% of concentration on
front denuder
8.6
4.1
4.4
2.8
5.2
1.1
Maximum concentration
as % of concentration on
front denuder
[233.3](a)
53.8
11.3
17.2
7.5
45.9
2.5
Percent of samples with
breakthrough greater than
10% of front denuder
29
10
10.7
0
17.2
0
(a) Suspect value rejected based on Q-test and not included in other calculations. This value corresponded to an NH3
concentration that was less than the minimum detectable NH3 concentration.
4.2.3 Duplicate Samples
For at least 10% of the reference samples, duplicates were collected using a collocated sampling
train (within 1 meter). The relative percent difference (RPD) between the duplicate samples was
calculated by dividing the absolute difference of the sample concentrations by the average of the
sample concentrations.
Table 4-3 summarizes the results of the duplicate sampling for Phase n. During Phase n,
duplicate samples were collected during every sampling period at the sampling location next to
the trailer, resulting in a total of 35 duplicate measurements. The absolute RPD varied between
0.7% and 32%, with an average of 7%. The absolute RPD for 7 of the duplicate samples
exceeded the QA limit of 10% specified in the test/QA plan. To verify the quality of the
reference method, NH3 gas standards were delivered to the reference method. Repeated delivery
of the same concentration standard gave an average RPD of 1.3%. Thus, it is probable that the
exceedences were caused by non-uniformity in the air sampled and did not impact the quality of
the reference method itself. However, some contributions may result from small variations in
sampling flow rates and analytical uncertainties.
4.2.4 Laboratory Blanks
Laboratory blank solutions were prepared for the FIA using distilled, deionized water. In each
analytical batch, at least 10% of the number of reference samples analyzed were laboratory
blanks and were submitted to the laboratory as blind samples. The analysis of the laboratory
blanks deviated from the test/QA plan in that, rather than submitting the blanks routinely (e.g.,
every tenth sample), the blanks were interspersed among the other samples and submitted as
12
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Table 4-3. Duplicate Sampling During Phase II
RPD (%)
Absolute Difference
(PPb)
Average
7
5
Maximum
32
18
Minimum
0.7
0.6
Number of duplicate samples
35
Number with RPD >10%
7
blind samples. (Note: The test/QA plan indicates that laboratory blanks should not exceed 5% of
any concentration measured on that day. As written, this threshold includes field blanks and
backup denuder samples. A deviation report has been filed to change this threshold so that it
applies only to composite reference samples and does not include samples that would be
expected to have low concentrations, such as field blanks.) During Phase n, a total of 27
laboratory blank samples were analyzed. The analytical results from the laboratory blanks
indicated no apparent drift in the baseline of the FIA, and none of the blank values was greater
than 5% of the lowest measured reference sample on that day.
4.2.5 Calibration Checks
In addition to analyzing every 15th calibration check samples, as described in Section 4.1.2, at
least 10% of the samples were submitted to the laboratory as blind calibration check samples.
These blind calibration check samples were prepared by diluting NIST-traceable NH4+ standard
stock solution.
During Phase n, 24 calibration check samples were prepared from four different standard
solutions. Measured concentrations for six of these calibration check samples differed from the
delivered standard concentration by more than 10%, and the full set of measured values was on
average 4.4% lower than the delivered concentration. Of the six calibration check samples that
failed, five were prepared from two of the four standard solutions. It is possible that the failures
may be attributable to inadvertent dilution or degradation of the standard solutions used, since
these standards were prepared prior to submission of the first samples and failed consistently
only near the end of the analysis period. The sixth calibration check sample that failed may be
associated with a transcription error in the submission log.
4.2.6 Gas Standard Dilution Checks
At each of the nominal NH3 levels to be used for the accuracy and linearity checks, at least one
sample of the dilution of the NH3 gas standard was collected using the reference method. These
samples were analyzed as regular samples and used to check the accuracy of the dilution system.
13
-------
Figure 4-2 shows the measured NH3 captured by the sampling cartridges versus the NH3
delivered during the dilution checks.
~ Reference Measurement
- 1:1 Line
y = 0.989x + 0.000
r2 = 1.000
CL
CL
"O
0
2
4
6
8
10
12
14
Standard Ammonia Concentration (ppm)
Figure 4-2. Analysis of Diluted Ammonia Standards Using the Denuder
Reference Method
A dilution check was conducted before Week 2 of Phase I. However, the sampling line was
thought to have not been flushed with the diluted NFL, sample prior to collecting the check
samples, and the measured concentrations did not agree within 10% of the expected concen-
tration. Consequently, the dilution check was repeated prior to Phase n, and the results are
shown in Figure 4-2. The average RA of the measured concentrations was 4% and indicates that
the NH3 gas standards as delivered by the dilution system were accurate with respect to the
reference method.
4.3 Audits
4.3.1 Performance Evaluation Audit
A performance evaluation audit was conducted to assess the quality of the measurements made
in this verification test. This audit addressed only those measurements that factor into the data
used for verification, i.e., the sample flow rate and the analytical laboratory measurements. This
audit was performed once during the verification test by analyzing a standard or comparing a
reading to a reference that was independent of standards used during the testing.
14
-------
The flow rates of the reference method sampling assemblies were audited once during testing
using a flow meter independent of the meter used to calibrate the flow rate. During Phase I,
agreement between the audit flow rate and the nominal flow rate indicated a bias in the
calibrated flow rates. The flow rates were recalibrated. The bias was later attributed to a faulty
audit flow meter, and the original flow calibrations were verified against a second audit flow
meter.
The performance of the FIA was audited by analyzing an NH4+ standard independent of those
used for the calibration, but were the same as those used for the calibration checks described in
Section 4.2.5. These samples were provided as blind audit samples, and the operator of the FIA
was not aware of the concentrations of the samples. In several cases, agreement between the
measured concentration and the standard concentration was not within ± 10% (ranged from -
43% to 64%). The cause of the discrepancy was investigated but could not be identified. It is
possible that some of the discrepancy is attributable to uncertainties associated with dilution of
the stock 1,000 mg/LNH4+ standard solution. Multiple solutions were prepared, and only some
of those solutions showed discrepancies with the analytical results. The RA between the
reference samples collected during the gas standard dilution check (performed between Phases I
and II) and their expected values provide additional verification of the accuracy of the FIA.
4.3.2 Technical Systems Audit
Battelle's ETV Quality Manager performed a technical systems audit (TSA) of the performance
of this verification test during the test. The purpose of this TSA was to ensure that the verifica-
tion test was being performed in accordance with the test/QA plan(2) and that all QA/QC
procedures were implemented. As part of the audit, Battelle's ETV Quality Manager reviewed
the reference sampling and analysis methods used, compared actual test procedures to those
specified in the test/QA plan, and reviewed data acquisition and handling procedures. Observa-
tions and findings from this audit were documented and submitted to the Battelle Verification
Test Coordinator for response. The records concerning the TSA are permanently stored with the
Battelle Quality Manager.
4.3.3 Audit of Data Quality
At least 10%) of the data acquired during the verification test was audited. Battelle's Quality
Manager 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 during the technical review process.
4.4 QA/QC Reporting
Each audit was documented in accordance with Sections 3.3.4 and 3.3.5 of the QMP for the
ETV AMS Center.(5) Once the audit 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.
15
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4.5 Data Review
Records generated in the verification test were reviewed before these records were used to
calculate, evaluate, or report verification results. Table 4-4 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. In some
cases, entries in the laboratory record books or on field data sheets were not reviewed within two
weeks. A deviation report was filed to address this.
Table 4-4. Data Recording Process
Data to be Recorded
Responsible
Party
Where Recorded
How Often
Recorded
Disposition of
Data(a)
Dates, times of test
events (site activities,
etc.)
USD A/
Battelle staff
Laboratory record
books/field data sheet.
Start/end of test, and
at each test activity.
Used to organize/
check test results;
manually
incorporated in data
spreadsheets as
necessary.
Reference method
sampling data
USD A/
Battelle staff
Laboratory record
books, chain-of-
custody forms, or file
data sheets as
appropriate.
At least at start/end
of reference sample,
and at each change
of a test parameter.
Used to organize/
check test results;
manually
incorporated in data
spreadsheets as
necessary.
Meteorological
conditions
Battelle
Meteorological station
data logger.
Continuously.
Used to assess
meteorological
conditions during
testing as necessary.
Ammonia analyzer
readings
Vendor or
designee
Data acquisition
system (data logger,
PC, laptop, etc.).
Continuously at
specified acquisition
rate throughout
analyzer operation.
Electronically
transferred to
spreadsheets.
Reference sample
analysis and results
USD A/
Battelle staff
Laboratory record
books, data sheets, or
data acquisition
system, as
appropriate.
Throughout sample
handling and
analysis process.
Transferred to
spreadsheets.
(a) All activities subsequent to data recording
were carried out by Battelle.
16
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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.
5.1 Relative Accuracy
The percent difference (%D) of the average TGA310 response to each NH3 gas standard was
calculated according to Equation 1:
%D = ZziLx100 «
where x is the average TGA310 response to an NH3 gas standard of nominal concentration xn.
During Phase n, the RA with respect to all of the gas standards (n) delivered to the TGA310 was
calculated using Equation 2:
Average RA = - ^ |%D, \j x 100
(2)
5.2 Linearity
Linearity was assessed by a linear regression analysis using the compressed gas standard con-
centrations as the independent variable and results from the TGA310 as the dependent variable.
Linearity was expressed in terms of slope, intercept, and r2 value. The 95% confidence interval
(CI) for the slope and intercept was also calculated.
5.3 Precision
Precision was calculated in terms of the percent relative standard deviation (RSD) of the
TGA310 measurements of several NH3 gas standards. The mean and standard deviations of
those readings were calculated. The RSD was then determined as:
SD
RSD = —x 100
17
(3)
-------
where SD is the standard deviation of the TGA310 readings and * is the mean of the TGA310
readings.
5.4 Response Time
Response time was assessed in terms of both the rise and fall times of the TGA310 when
sampling NH3 gas standards or zero air. Rise time (i.e., 0% to 95% response time for the change
in NH3 concentration) was determined from the TGA310 response to a rapid increase in the
delivered NH3 concentration. Once a stable response was achieved with the gas standard, the fall
time (i.e., the 100% to 5% response time) was determined in a similar way, switching from the
NH3 standard back to zero air or a lower concentration NH3 gas standard. Rise and fall times
were determined for the TGA310 during testing. Response times are reported in terms of
seconds (s). It should be noted that response times include the time associated with equilibration
of NH3 on the tubing and inlet surfaces during delivery of the gas standards.
5.5 Calibration and Zero Drift
Calibration and zero drift are reported in terms of the mean, RSD, and range (maximum and
minimum) of the readings obtained from the TGA310 in the repeated sampling of the same NH3
standard gas and of zero air. For zero drift, the SD is reported instead of the RSD since dividing
the SD by a value approximately equal to zero is not meaningful. The calibration and zero drift
were calculated during Phase II of testing so that up to six NH3 standard and zero air readings
(on Tuesday, Wednesday, and Friday of Weekl and Monday, Wednesday, and Friday of
Week 4) were used for this calculation. This calculation, along with the range of the data,
indicates the day-to-day variation in zero and standard readings.
5.6 Interference Effects
The extent of interference was calculated in terms of the ratio of the response of the TGA310 to
the interfering species, relative to the actual concentration of the interfering species. For
example, if 100 ppb of an interfering species resulted in a 1-ppb increase in the NH3 reading of
the TGA310, the interference effect was reported as 1% (i.e., 1 ppb/100 ppb). The interference
effect was reported separately for each interferent, both in the absence and in the presence of
nh3.
5.7 Comparability
Comparability between the TGA310 results and the reference method results with respect to
ambient air was assessed by linear regression using the reference method NH3 concentrations as
the independent variable and results from the TGA310 as the dependent variable. Comparability
was expressed in terms of slope, intercept, and r2 and was calculated for Phase II of the
verification test.
18
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Chapter 6
Test Results
The results of the verification test of the TGA310 are presented in this section. During testing,
the TGA310 was set to collect 3-second average readings. For data logging purposes, a
parameter (deltaConc) can be set to optimize the number of points recorded in the database
(optimize the database size). This parameter is a percentage of the difference between two
recorded points and was set to 1% for this verification test. Therefore, if the difference was
greater than "deltaConc," the value was recorded in the database; whereas, if the difference was
lower than "deltaConc," the value was not recorded. The values presented here are based on the
data recorded with these settings. The TGA310 was not available for testing during Phase I of
the verification test. Therefore, the results presented are from Phase II only.
Meteorological conditions collected using the meteorological monitoring station during Phase II
are presented in Figure 6-1. The average ambient temperature was 4.5°C (range: -10 to 29°C),
and the average relative humidity was 75%. Winds were predominantly from the northwest and
quite variable in speed, averaging 7 miles per hour (30 miles per hour maximum). Figure 6-1
shows the Phase II wind direction, wind speed, and ambient temperature data and the ambient
NH3 data set collected by the TGA310 (bottom panel). The shaded region shows the period
during which NH3 reference measurements were conducted. The TGA310 was installed and
began recording data on the second day of Phase n, as shown in the figure. The two gaps in the
TGA310 ambient data set were caused by computer-related failures and are discussed in Section
6.8. The TGA310 NH3 measurements ranged from 3 to 1,648 ppb during Phase II and averaged
166 ppb.
6.1 Relative Accuracy
During the first week of Phase n, the TGA310 was supplied with compressed NH3 gas standards
at a variety of concentrations to assess RA. The compressed NH3 gas standards were diluted in
zero air and delivered to the inlet of the TGA310 at a flow rate of 1 Lpm. It should be noted that
frequency and phase instability warnings and alarms sounded on the TGA310 during the
delivery of gas standards from the NH3 dilution system. The instabilities were probably caused
by small fluctuations in the NH3 dilution system output flow rate; alarms did not sound when
zero air was delivered directly from the compressed gas cylinder, bypassing the dilution system.
The alarms sounded during 16% of the gas standard delivery periods.
19
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1500 —
Reference Measurement Penod
000-
E 500-
10/21/03 10/26/03 10/31/03 11/5/03
Date
Figure 6-1. Phase II Meteorological Conditions and TGA310
Ambient NH3 Measurements
11/10/03 11/15/03
Figure 6-2 presents the NH3 concentrations recorded by the TGA310 during the RA checks,
along with the nominal NH3 concentration levels supplied to the TGA310. The TGA310
response to the 1,000-ppb NH3 standard was unstable for approximately the first 15 minutes of
the standard delivery; activities in the instrument trailer may have disrupted the TGA310
stability. As with the other gas standard concentrations, the RA calculation does not include data
obtained when the TGA310 signal appeared to be unstable. The gap in the data between the
600-ppb and 2,000-ppb standards resulted from the loss of NH3 during the delivery of these two
standards. The supply of NH3 ran out shortly after delivery of the 600-ppb standard; the NH3
flow was reestablished and used for delivery of the 2,000-ppb standard. The averages of the
20
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3000
—i—TGA310
Gas Standard Concentration
2500 -
-Q
Q.
g' 2000
2000 ppb
-t—'
<0
-t—<
C
CD
O
c
o
O
CO
'§ 1000 -
E
E
<
500 -
NH3 Supply
Restarted
1500
1000 ppb
600 ppb
NH3 Supply
Depleted
300
ppb
0 ppb
0:00
1:00
2:00
3:00
4:00
5:00
Elapsed Time
Figure 6-2. Phase II Accuracy Results for the TGA310
measurements at each nominal NH3 concentration are presented in Table 6-1 along with the
calculated %D and the number of data points used in the calculations. The %Ds of the TGA310
ranged from -2.9% to 2.5% over the four concentration levels measured, and the RA (i.e., the
average of the absolute values of the %Ds) was 2.2%.
Table 6-1. Relative Accuracy Results
NH3 Gas Standard
Concentration (ppb)
Average Measured
Concentration (ppb)
Number of
Data Points
Percent
Difference (%)
0
0.7
227
NA
300
306
248
2.0
600
615
275
2.5
1,000
986
117
-1.4
2,000
1941
25
-2.9
Average RA
2.2%
NA = not applicable.
21
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6.2 Linearity
Figure 6-3 shows the results of the linearity check for Phase n. A linear regression of the
TGA310 response versus the gas standard concentration, over the range from 0 to 2,000 ppb,
showed a slope of 0.966 (± 0.031), an intercept of 15.9 (± 31.9) ppb, and a coefficient of
determination (r2) of 1.000, where the numbers in parentheses represent the 95% CI.
2500
Measurement Data
1:1 Line
2000
¦Q
Q.
Q.
C
o
H—<
2
H—<
c
1500
CD
O
c
o 1000
CD
CD
y = 0.966x + 15.9
r2 = 1.000
CD
< 500
0
500
1000
1500
2000
2500
Gas Standard Concentration (ppb)
Figure 6-3. Results of Linearity Check of the TGA310
During Phase II
6.3 Precision
Table 6-2 presents the calculated precision of the TGA310 measured during the accuracy and
linearity checks. The precision of the TGA310 readings varied from 0.4 to 1.2% RSD at the four
NH3 levels measured in the accuracy/linearity checks, with an average precision of 0.9%.
22
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Table 6-2. Calculated Precision of the TGA310
NH3 Gas Standard
Concentration (ppb)
Average Measured
Concentration (ppb)
Number of
Data Points
RSD
(%)
300
306
248
1.0
600
615
275
1.2
1,000
986
117
1.0
2,000
1,941
25
0.4
Average RSD
0.9
6.4 Response Time
Response time was determined during Phase II from the amount of time required for the
TGA310 to rise to 95% of each of the expected concentrations or to fall by 95% of the stable
readings during the accuracy/linearity checks. Table 6-3 presents a summary of the response
time determinations for the TGA310. Measured rise times were 126 and 156 seconds
(approximately two to two and a half minutes); the fall times were 124 and 169 seconds
(approximately two to three minutes). The response times were measured with a sample flow
rate of 1 Lpm. Response times are likely to be shorter for higher flow rates up to 5 Lpm,
although this was not verified in this test.
Table 6-3. Response Time Determinations
Change (ppb)
Rise Time (seconds)
Fall Time (seconds)
0 - 1,000
126
-
1,000 - 300
-
124
300 - 600
156
-
2,000 - 0
-
169
6.5 Calibration and Zero Drift
The calibration/drift checks were conducted by supplying NH3 gas and zero air to the TGA310
on Tuesday, Wednesday, and Friday during Week 1 and on Monday, Wednesday, and Friday
during Week 4 of Phase n. The results of the Phase II calibration and drift checks are summar-
ized in Table 6-4, including the number of measurements used for each calculation. The values
reported in this table are based on the average readings during each calibration and zero check
when the readings of the TGA310 had stabilized (i.e., the signal was neither visibly increasing
nor decreasing); thus, the calculations for each check span somewhat different time periods that
23
-------
range from nine to 16 minutes. These results indicate no apparent drift in the response of the
TGA310 to zero air, although the zero reading was slightly higher during Week 4. The TGA310
response to the 1,000-ppb NH3 standard was higher at the end of the week than at the beginning
of the week during both Week 1 (81 ppb higher) and Week 4 (55 ppb higher), although an
overall drift over the 4-week phase was not apparent.
Table 6-4. Calibration and Zero Checks During Phase II
Zero Check
Calibration Check(a)
Max-
Min-
Number
Max-
Min-
Number
Check
Mean
SD®
imum
imum
of Data
Mean
RSD
imum
imum
of Data
Number
(PPb)
(PPb)
(PPb)
(PPb)
Points
(PPb)
(%)
(PPb)
(PPb)
Points
Week 1
Tuesday
0.7
0.3
1.4
0.2
224
986
1.0
1,003
963
117
Week 1
Wednesday
1.7
0.1
2.0
1.4
128
981
1.1
997
964
109
Week 1
Friday
1.2
0.0
1.2
1.1
113
1,067
0.7
1,083
1,057
84
Week 4
Monday
4.9
0.8
6.7
3.7
101
1,004
0.9
1,024
987
86
Week 4
Wednesday
2.2
0.6
3.4
1.2
92
1,054
0.7
1,070
1,041
71
Week 4
Friday
2.9
0.1
3.1
2.7
99
1,059
2.0
1,185
1,043
95
(a) 1,000 ppb NH3 nominal concentration.
(b) SD reported for zero drift check since the RSD is not meaningful for near-zero values.
6.6 Interference Effects
The effect of potential interferent gases on the response of the TGA310 was assessed by
supplying the TGA310 with a series of four gases (hydrogen sulfide, nitrogen dioxide,
1,3 butadiene, diethylamine) in zero air and a 500-ppb NH3 standard. The response of the
TGA310 during the introduction of these gases is summarized in Table 6-5. The interference gas
concentrations carry an uncertainty of approximately ± 15% (as reported by the manufacturer for
uncertified permeation tubes). The response of the TGA310 to both hydrogen sulfide and
nitrogen dioxide was negligible; however, the response of the TGA310 to 1,3-butadiene and
diethylamine showed an increase between 20% and 28% in both a zero air matrix and an NH3
matrix. Independent tests have indicated the presence of NH3 in the diethylamine gas standard
that may be present as an impurity or as a result of displacement from tubing walls during the
delivery of the diethylamine standard. Thus, the measured interference may be at least partially
due to this NH3 impurity.
24
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Table 6-5. Interference Effect Evaluation
Interference Effect (%
Gas
Interferent Gas
Concentration (ppb)
Zero-Air Matrix
500-ppb NH3 Matrix
Hydrogen sulfide
Nitrogen dioxide
1,3-Butadiene
Diethylamine
461
154
154
155
-0.1(a)
-0.2(a)
24
28
(a)
Signal not significantly different from baseline without interferent gas.
-0.3(a)
0.5(a)
22
20
6.7 Comparability
Figure 6-4 shows the NH3 concentrations measured using the reference method, along with the
corresponding average readings of the TGA310 for the reference sampling periods during Phase
n. In general, the TGA310 appeared to track changes in NH3 concentrations measured with the
reference method. These data are also presented in Figure 6-5 as a scatter plot to illustrate the
correlation between the reference and TGA310 data. A linear regression of the TGA310
response versus the reference method concentration showed a slope of 1.15 (± 0.04), an intercept
of -4.1 (± 3.6) ppb, and an r2 of 0.994, where the numbers in parentheses represent the 95% CI.
350
-Q 300
Q.
250 --
CD
c
-------
400
Measurement Data
1:1 Line
350
O)
c
250
CD
01
200
o
CO
<
O
I—
r2 = 0.994
150
CD
O)
2
o> 100
<
0
50 100 150 200 250 300 350 400
Reference Ammonia Concentration (ppb)
Figure 6-5. Scatter Plot of the TGA301 Results versus
Ambient Reference Measurements During Phase II
6.8 Ease of Use
The TGA310 was installed on the second day of Phase II by a vendor representative, who
completed the installation in several hours. The installation could be completed by an operator
with minimal experience and the TGA310 manual. The vendor was on-site for less than one day,
which allowed enough time to complete the installation and train Battelle and USDA staff to use
the TGA310 and check its performance. Checklists, shown in Appendix A, were completed
daily by Battelle/USDA staff. The checks were quick and straightforward and could be
completed by an inexperienced user, although some instruction was necessary to download data
and navigate the various menus in the TGA310 software. During Phase II of testing, no
maintenance was performed on the TGA310. Table 6-6 presents a summary of activities
involving the TGA310 during Phase n. Several TGA310 internal warnings and alarms sounded
during this verification test, as discussed previously and summarized in Table 6-6. In general,
the alarms were caused by temperature changes in the instrument trailer and small fluctuations
in the output flow rate of the NH3 dilution system (alarms observed during delivery of gas
standards to the TGA310). The potential consequence of the conditions that caused the warnings
and alarms is added noise in the TGA310 measurements. The TGA310 did not produce any
waste during the test.
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Table 6-6. Activities Performed and Power Outages During Phase II
Time
Down
Service
Offline(a)
Time(b)
Time(c)
Date
(minutes)
(minutes)
(minutes)
Activity
10/21/03
305
Delivered zero air and NH3 standard®
10/21/03
(20)(e)
—Alarm: Frequency Noisy
10/21/03
(5)(e)
—Warning: Frequency Stabilizing
10/22/03
125
Delivered zero air and NH3 standard®
10/22/03
(10)(e)
(20)(e)
(l)(e)
—Alarm: Frequency Noisy
—Warning: Frequency Stabilizing
—Warning: Phase Stabilizing
10/24/03
105
(l)(e)
Delivered zero air and NH3 standard®
—Alarm: Frequency Noisy
10/26/03
1,295
5
Data loss: computer time changed automatically for
daylight savings, with user prompt.
11/2/03
1,080
5
Data loss: computer power shut down overnight.
User restart.
11/7/03
660
5
Data loss: TGA310 program stopped running
overnight. User restart.
11/10/03
60
Delivered zero air and NH3 standard®
11/10/03
(50)(e)
—Warning: Frequency Stabilizing
11/11/03
310
(5)(e)
(2)(e)
Performed interference test®
—Alarm: Frequency Noisy
—Warning: Frequency Stabilizing
11/12/03
100
(10)(e)
(40)(e)
(5)(e)
Delivered zero air and NH3 standard®
—Alarm: Frequency Noisy
—Warning: Frequency Stabilizing
—Warning: Phase Stabilizing
11/14/03
(390)(e)
Alarm: System Overheat
11/14/03
110
(5)(e)
(l)(e)
Delivered zero air and NH3 standard®
—Alarm: Frequency Noisy
—Warning: Frequency Stabilizing
10/21 - 11/14/03
(14,615)(e)
Warning: Temperature Fluctuation
Totals
1,115
3,035
(15,180 )(e)
15
91% (87%>)® data completeness® and 15-minute
service time.
(a) Time Offline = time that the TGA310 was taken offline for zero or standard gas measurements. The period over which time
offline was evaluated began at 2:00 p.m. on 10/21/03 and ended at the conclusion of testing at 5:00 p.m. on 11/14/03. The
amount of time was rounded to the nearest 5 minutes.
(b) Down Time = time that the TGA310 was not operating or was operating but not reporting reliable measurements. The period
over which down time was evaluated began at 2:00 p.m. on 10/21/03 and ended at the conclusion of testing at 5:00 p.m. on
11/14/03. The amount of time was rounded to the nearest 5 minutes for times greater than 5 minutes.
(c) Service Time = time spent conducting routine operation and maintenance activities and troubleshooting problems. The period
over which service time was evaluated began at 2:00 p.m. on 10/21/03 and ended at the conclusion of testing at 5:00 p.m. on
11/14/03. The amount of time was rounded to the nearest 5 minutes.
(d) Testing activity performed by Battelle/USDA operator.
(e) Data continued to be measured and recorded during periods when TGA310 alarms and warnings sounded. These times were not
included in the data completeness calculation.
(f) The TGA310 was installed on the second day of Phase II, missing 30 hours of time during which data could have been
collected. If this time is considered in the data completeness calculation, the TGA310 experienced 90% data completeness
during Phase II.
(B) Data Completeness = the ratio of time that the TGA310 was not experiencing down time to the total time available for
monitoring ambient NH3 mixing ratios from the start of testing on 10/21/03 to the end of testing on 11/14/03. The total time
that was available for monitoring during Phase II was 34,741 minutes or 579 hours.
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The TGA310 software was quite flexible, which made it easy for the operator to archive data
from specific time periods into separate files. The computer for the TGA310 stored the complete
data set for Phase II and did not need to be downloaded during the test. However, data could be
downloaded at any time by copying files onto an external disk drive (e.g., a "thumb" drive). The
data archive files could be exported as text or Excel files using the TGA310 Viewer software
that was provided by the vendor. Data were automatically archived every four hours, resulting in
archive files of approximately 500 kilobytes each. The archive files produced for Phase II
consumed approximately 60 megabytes of disk space. Operator input was required to respond to
the PC prompt to change the time for daylight savings, and some data were lost as a result. On
two occasions, the operator found that the computer for the TGA310 had shut down or that the
TGA310 program had stopped running at some point overnight. The cause of these events (e.g.,
power failure/interruption, software glitch) is not known, and some loss of data resulted. Based
on information from the vendor that was not verified as part of this test, the TGA310 now
includes an automatic restart that is expected to resolve this problem.
6.9 Data Completeness
During Phase n, data completeness for the TGA310 was 91%. The data loss of 9% was caused
by computer-related failures, as described in Section 6.8.
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Chapter 7
Performance Summary
The performance of the TGA310 was evaluated only in Phase II of this verification test. Table 7-
1 presents a summary of the performance of the TGA310 during Phase II of this verification test.
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Table 7-1. Performance Summary of the TGA310
Parameter
Phase I
Phase II
Relative accuracy1-3-1
Average RA = 2.2%
Percent difference range = -2.9 to 2.5%
Linearity(a)(b)
Range = 0 to 2,000 ppb NH3
Slope = 0.966 (±0.031)
Intercept =15.9 ppb (±31.9)
r2 = 1.000
Precision1-3-1
Average RSD = 0.9%o
Range = 0.4 to 1.2%
Response time(a)
Rise time = 126 to 156 seconds (1 Lpm flow rate)
Fall time = 124 to 169 seconds (1 Lpm flow rate)
Calibration/
zero drift(a)
The TGA310 was not
• No apparent drift in response to zero air.
• Response to 1,000-ppb NH3 gas standard increased by
81 ppb between Tuesday and Friday of Week 1. An
increase of 55 ppb was observed between Monday and
Friday of Week 4.
Interference
effects(a)(c)
available in Phase I
• Hydrogen sulfide (461 ppb): no apparent effect
• Nitrogen dioxide (154 ppb): no apparent effect
• 1,3-Butadiene (154 ppb): increase of 24%o in zero air
and 22%o in 500 ppb NH3
• Diethylamine (155 ppb): increase of 28%o in zero air and
20% in 500 ppb NH3(d)
Comparability
Slope = 1.15 (±0.04)
Intercept = -4.1 ppb (±3.6)
r2 = 0.994
Ease of use
• Daily checks were simple and quick
• Little skill required to operate
• No data download necessary
• No maintenance required
• Loss of approximately 29 hours of data resulting from
apparent computer-related failures
Data completeness
91 %(e) (87%)®
(a) Frequency and phase instability warnings and alarms sounded on the TGA310 during 16% of the gas standard delivery periods
when gas standards were supplied by the NH3 dilution system. Warnings were probably caused by small fluctuations in the gas
standard flow rate.
(b) Relative accuracy is expressed as an average absolute value of the percent difference from NH3 gas standards.
(c) Calculated as the change in signal divided by the interferent gas concentration, expressed as a percentage.
(d) Independent tests indicate that the diethylamine gas standard contained some NH3 as an impurity in the gas standard or as a
result of displacement from the tubing walls. Thus, the measured interference was at least partially due to the NH3 impurity.
(e) Data loss of 51 hours attributable to computer-related failures.
(f) The TGA310 was installed 30 hours after the start of Phase II. If this time is considered, the TGA310 experienced 87% data
completeness.
30
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Chapter 8
References
1. National Air Pollutant Trends, 1900-1998. EPA-454/R-00-02, U.S. Environmental
Protection Agency, Office of Air Quality Planning and Standards, Research Triangle Park,
North Carolina, 27711.
2. Test/QA Plan for Verification of Ambient Ammonia Monitors at Animal Feeding
Operations, Battelle, Columbus, Ohio, September 2003.
3. Determination of Reactive Acidic and Basic Gases and Acidity of Fine Particles (<2.5
/dm), Environmental Protection Agency Compendium Method 10-4.2, EPA/625/R-
96/01 OA, U.S. Environmental Protection Agency, Office of Research and Development,
Cincinnati, Ohio, 45268.
4. Operating Manual, ChemComb Model 3500 Speciation Sampling Cartridge, Revision A,
January 2000, Rupprecht & Patashnick Co., Inc. East Greenbush, New York, 12061.
5. Quality Management Plan (QMP) for the ETV Advanced Monitoring Systems Center, U. S.
EPA Environmental Technology Verification Program, prepared by Battelle, Columbus,
Ohio, Version 4.0, December 2002.
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Appendix A
TGA310 Checklist
A-l
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TGA300Series - Ammonia Trace Gas Analyzer - ^
. usens
Operation Checklist
Purpose of the document;
The present document provides some guideline information intended to check the operation of the instrument on a regular
basis. The document refers to the "Installation checklist" report, filled by the person in charge of the installation, and provides
the parameters and measured raw data at the time of the first installation.
General Information:
. Measuring unit S/N : - - - Location
. Flow control S/N : - Date
Operation Checklist;
1, Log In In the main panel of the Graphical User Interface, tag in as
"Maintenance", log off and tog in if necessary
2 Chech the Diagnostic panel Go to Menu and select Diagnostic
3, Cheek the status & diagnostic • Are the indicators status in the Diagnostic panel OK {they all ~ yM p
should be green {ideal) except 'temperature" during the
warming up time}?
4, Record Raw Data values •Record instrument the values displayed in the diagnostic panel:
Raw Data:
Frequency [Hz] :
Normalized signal [mV] :
Ref. Amplitude [mV] :
Phase [tad] :.
Temperature ("C] :
Relative Humidity [%) :
Speaker [mVJ :
5, Check Ref value • Is the Ref value is within 30% margin around the value p ym q |^0
recorded at the time of the installation ?
TGA300Senes Operation Checklist
© Omnisens. Version t„ Gcto&er 2003
A-2
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sens
Pare Scienfitique sur te Sile de I'EPFL
PSE-C
CH-1015 Lausanne, Switzerland
Phone: i\ " ¦*- - 47
Fox: <<11 "" 0 ''
tmoili ii
8, Log OFF
Go back to the main panel arid tog OFF
7, Cheek the recorded archives Select "Archive Viewer'on the main panel menu
• Are recorded archives aeeessibte with the "Archive vmvmr ? D yes Q No
8. Sampling pump & air flow
* is the air flow rate adjusted to the proper value (between
1.5 and 4 liter/mm.}?
~ Yes. O No
Operator's name :
Signature :
In case of problem or if the answer to one the above question was NO, contact and fax or email the present document to:
Qmnisens SA
PSE-C
CH1015 Lausanne
Switzerland
Phone: +41 21893 84 88
Fax: +411274 20 31
Email: syppgrtSomnjsens.eh
Important Note;
For debugging purposes, it is very helpful if the archived data is made available. Therefore in case of problem, zip the archive
folder Attsh (C://OmnBens/Data/Arch)and email :t to lyacedtSffiELiaSMLSii
conhdentw. omnisens - a- vmion i.
A-3
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