July 2004
Environmental Technology
Verification Report
Pranalytica, Inc.
Nitrolux™ 1000 Ambient Ammonia Analyzer
Prepared by
Battelle
Battelle
l%e Business of Innovation
In collaboration with the
U.S. Department of Agriculture
Under a cooperative agreement with
U.S. Environmental Protection Agency
ElV etV etV
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July 2004
Environmental Technology Verification
Report
ETV Advanced Monitoring Systems Center
Pranalytica, Inc.
Nitrolux™ 1000 Ambient 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/or 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 4
3.1 Test Design 4
3.2 Site Descriptions 5
3.2.1 Site Description—Phase I 5
3.2.2 Site Description—Phase II 6
3.3 Test Procedures 6
3.3.1 Accuracy, Linearity, Precision, and Response Time 6
3.3.2 Calibration and Zero Drift 7
3.3.3 Interference Effects 7
3.3.4 Comparability 7
4 Quality Assurance/Quality Control 10
4.1 Equipment Calibrations 10
4.1.1 Reference Method Sampling Equipment 10
4.1.2 Analytical Equipment 10
4.1.3 Meteorological Equipment 11
4.1.4 Ammonia Dilution System 11
4.2 QC Samples 11
4.2.1 Field Blanks 11
4.2.2 Denuder Breakthrough Checks 13
4.2.3 Duplicate Samples 16
4.2.4 Laboratory Blanks 17
4.2.5 Calibration Checks 18
4.2.6 Gas Standard Dilution Checks 18
4.3 Audits 19
4.3.1 Performance Evaluation Audit 19
4.3.2 Technical Systems Audit 20
4.3.3 Audit of Data Quality 20
4.4 QA/QC Reporting 20
4.5 Data Review 21
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5 Statistical Methods and Reported Parameters 22
5.1 Relative Accuracy 22
5.2 Linearity 22
5.3 Precision 22
5.4 Response Time 23
5.5 Calibration and Zero Drift 23
5.6 Interference Effects 23
5.7 Comparability 24
6 Test Results 25
6.1 Relative Accuracy 27
6.2 Linearity 31
6.3 Precision 34
6.4 Response Time 35
6.5 Calibration and Zero Drift 35
6.6 Interference Effects 38
6.7 Comparability 38
6.8 Ease of Use 41
6.9 Data Completeness 42
7 Performance Summary 44
8 References 46
Appendix A. Nitrolux 1000 Checklist A-l
Figures
Figure 2-1. Pranalytica's Nitrolux 1000 Ambient NH3 Analyzer 2
Figure 3-1. Phase I Test Site 5
Figure 3-2. Phase II Test Site 6
Figure 3-3. Reference Method Sampling Cartridge 8
Figure 4-1. Denuder Breakthrough During Phase I as a
Function of Integrated NH3 Concentration 14
Figure 4-2. Denuder Breakthrough During Phase II as a
Function of Integrated NH3 Concentration 15
Figure 4-3. Analysis of Diluted NH3 Standards Using the
Denuder Reference Method 19
Figure 6-1. Phase I Meteorological Conditions and Nitrolux 1000
Ambient NH3 Measurements 25
Figure 6-2. Phase II Meteorological Conditions and Nitrolux 1000
Ambient NH3 Measurements 26
Figure 6-3a. Week 1, Phase I Accuracy Results for the Nitrolux 1000 28
Figure 6-3b. Week 4, Phase I Accuracy Results for the Nitrolux 1000 28
Figure 6-4a. Week 1, Phase II Accuracy Results for the Nitrolux 1000 29
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Figure 6-4b. Week 4, Phase II Accuracy Results for the Nitrolux 1000 29
Figure 6-5a. Nitrolux 1000 Linearity Check During Week 1 of Phase I 32
Figure 6-5b. Nitrolux 1000 Linearity Check During Week 4 of Phase I 32
Figure 6-6a. Nitrolux 1000 Linearity Check During Week 1 of Phase II 33
Figure 6-6b. Nitrolux 1000 Linearity Check During Week 4 of Phase II 33
Figure 6-7. Comparison of Ambient Reference Measurements with Averages from
the Nitrolux 1000 During Phase I 39
Figure 6-8. Comparison of Ambient Reference Measurements with Averages from
the Nitrolux 1000 During Phase II 39
Figure 6-9. Scatter Plot of Averages from the Nitrolux 1000 versus
Ambient Reference Measurements During Phase I 40
Figure 6-10. Scatter Plot of Averages from the Nitrolux 1000 versus
Ambient Reference Measurements During Phase II 40
Tables
Table 4-1. Minimum Detectable Ambient NH3 Concentrations During Phase I 12
Table 4-2. Minimum Detectable Ambient NH3 Concentrations During Phase II 13
Table 4-3. Denuder Breakthrough Checks During Phase I 15
Table 4-4. Denuder Breakthrough Checks During Phase II 16
Table 4-5. Duplicate Reference Method Samples 17
Table 4-6. Data Recording Process 21
Table 6-1. Relative Accuracy Results During Phase I 30
Table 6-2. Relative Accuracy Results During Phase II 31
Table 6-3. Calculated Precision of the Nitrolux 1000 During Phase I 34
Table 6-4. Calculated Precision of the Nitrolux 1000 During Phase II 35
Table 6-5. Response Time Determinations 36
Table 6-6. Calibration and Zero Checks During Phase I 37
Table 6-7. Calibration and Zero Checks During Phase II 37
Table 6-8. Interference Effect Evaluation 38
Table 6-9. Activities Performed During Phase I 42
Table 6-10. Activities Performed During Phase II 43
Table 7-1. Nitrolux 1000 Performance Summary 45
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List of Abbreviations
AFO
animal feeding operation
AMS
Advanced Monitoring Systems
CI
confidence interval
cm
centimeter
co2
carbon dioxide
DL
detection limit
EPA
U.S. Environmental Protection Agency
ETV
Environmental Technology Verification
FIA
flow injection analysis/analyzer
L
liter
Lpm
liters per minute
Hg
microgram
|im
micrometer
mg
milligram
mL
milliliter
mm
millimeter
NIST
National Institute of Standards and Technology
nh3
ammonia
nh4
ammonium
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
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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 Pranalytica, Inc. Nitrolux™ 1000 ambient
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 Nitrolux 1000. The following is a description of the Nitrolux
1000, based on information provided by the vendor. The information provided below was not
subjected to verification in this test.
The Nitrolux 1000 (Figure 2-1) is an ambient NH3 analyzer that uses resonant photoacoustic
spectroscopy and a line-tunable carbon dioxide (C02) laser to provide continuous or on-demand
measurements. A C02 laser is useful to excite NH3 because one of its laser lines is nearly
coincident with one of NH3's strongest spectral features. The excited NH, molecules undergo
collisional deactivation, which converts the absorbed energy into periodic local heating at the
modulation frequency of the laser. The resulting acoustic waves are detected with a low-noise
microphone to quantify NH3 with minimal interferences from carbon monoxide, hydrogen
sulfide, methane, sulfur oxides, nitrogen oxides, ozone, and other contributors at their typical
concentrations in a non-polluted atmosphere.
Q
The Nitrolux 1000 is sensitive to NH3 concentrations of 1 part per billion (ppb) and has a range
of 0 to 2,000 ppb with full-scale ranges of
20 to 2,000 ppb by automatic or manual
switching. The Nitrolux 1000 consists of a
sealed-off radiofrequency-excited 13C02
laser, whose operating wavelength can be
line-switched by using an intracavity
grating, a flow-through analysis cell, a
laser power meter, a signal processor, and
a single-board computer for controlling all
internal operations and analyzing the
signals to produce concentration readings
in real time. Optional analysis cells allow
for simultaneous measurement of two to
16 input streams. Samples are extracted in
a continuous mode at approximately 400
to 500 standard cubic centimeters (cm) per
minute and pass through a 40-micrometer
N
Figure 2-1. Pranalytica's Nitrolux 1000 Ambient
NH3 Analyzer
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(|im) in-line filter to remove particulate matter. Time-stamped NH3 concentration measurements
are stored on an internal hard disk.
Power requirements of the Nitrolux 1000 are 150 Watts at 110 volts, 60 Hertz alternating
current. It comes with a rack-mountable foldout 15-inch flat-panel video display, including
keyboard and mouse. The rack mount is 48.3 cm (19 inches) wide, 61.0 cm (24 inches) deep,
and 25.4 cm (10) inches high. It weighs 29.5 kilograms (65 pounds). The approximate cost of
the Nitrolux 1000 with rack mount display is $24,000. Additional particulate filters cost $250
each, and mounting rails for installation are $150 per pair.
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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 Nitrolux 1000'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,l2> 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
conducted 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.
During each phase of the verification test, the Nitrolux 1000 response to a series of NH3 gas
standards of known concentration was used to quantify relative accuracy (RA), linearity,
precision (repeatability), and calibration/zero drift. The Nitrolux 1000 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 Nitrolux 1000 response to various
chemical species that may be present at AFOs; the potential interferent gases were delivered
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both in the presence and absence of NH3. The Nitrolux 1000 response to ambient air was also
evaluated during both phases as the comparability to simultaneous determinations by an ambient
NH3 reference method (acid-coated denuders). Additionally, the ease of use of the Nitrolux 1000
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 Descriptions
The Nitrolux 1000 was installed at the Phase I and II testing locations by a vendor
representative. Battelle and USDA staff worked with the vendor representative to establish
procedures for operating the Nitrolux 1000 during this verification test. The vendor
representative trained Battelle and USDA staff to check several instrument parameters to verify
the operation of the Nitrolux 1000 and identify signs of malfunction. A checklist, provided by
the vendor representative and included as Appendix A, was completed daily by Battelle and
USDA staff. 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/or USDA staff. The vendor representative returned to the test site after the completion of
Phase I to install the Nitrolux 1000 at the Phase
II test site.
3.2.1 Site Description—Phase I
Figure 3-1 shows a schematic diagram of the
swine farm during Phase I of the verification test.
The AFO included ten animal barns arranged in
two parallel rows of five, with each barn housing
up to 2,000 swine. The urine and feces from the
swine exited the barns through metal gratings in
the floor and were deposited in two nutrient
lagoons located on the southern end of the AFO.
The perimeter of the AFO was lined with trees,
with agricultural fields surrounding the AFO
perimeter. A temperature-regulated instrument
trailer was placed on-site during the test to house
the monitoring equipment and to provide a
sheltered work space. The Nitrolux 1000 was
installed inside the instrument trailer, and a
Teflon inlet line was used to supply outside air to
the Nitrolux 1000. The inlet was mounted on a
tripod on the west side of the trailer at a height of
approximately 2 meters. The platform shown in
Figure 3-1 was installed to hold some of the
monitoring equipment.
Entrance
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Figure 3-1. Phase I Test Site
Trailer | | ~ Platform
Nutrient
Lagoons
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3.2.2 Site Description—Phase II
Figure 3-2 shows a schematic diagram of the cattle feedlot during Phase II of the verification
test. The instrument trailer used in Phase I of this verification test was also used in Phase II and
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. The Nitrolux 1000 was installed in
the instrument trailer as in Phase I, with an inlet height of approximately 1.5 meters.
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Figure 3-2. Phase II Test Site
3.3 Test Procedures
All tests utilized the continuous NH3 measurement data record stored by the Nitrolux 1000 that
were downloaded from the instrument and transferred digitally to computer spreadsheets for
analysis.
3.3.1 Accuracy, Linearity, Precision, and Response Time
During the first and last (fourth) week of each phase of testing, the Nitrolux 1000 was inde-
pendently supplied with compressed NH3 gas standards to achieve NH3 concentrations over a
range from 0 to 10,000 ppb (Phase I) or 0 to 2,000 ppb (Phase II) to simulate the range expected
in ambient air during each phase. The gases delivered to the Nitrolux 1000 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 Nitrolux 1000 for between 30 minutes and two hours at each
concentration level. Accuracy, linearity, and precision were established based on the continuous
digital data set recorded by the Nitrolux 1000 during the periods when the NH3 gas was
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supplied. Data were used for the calculations once the signal had stabilized at a constant concen-
tration (i.e., the signal did not appear to be increasing or decreasing with time). The time
required to reach 95% of the change in the stable reading for each concentration was also
recorded for the Nitrolux 1000. These data were used to assess the response time of the Nitrolux
1000.
3.3.2 Calibration and Zero Drift
On Monday, Wednesday, and Friday of the first and last weeks of testing during each phase, the
Nitrolux 1000 was supplied with a 1,000-ppb (nominal) NH3 gas standard and zero air to check
the calibration and zero drift of the Nitrolux 1000, respectively. Zero air and the 1,000-ppb NH3
standard were each supplied to the Nitrolux 1000 for approximately one hour, during which time
the measured concentrations were recorded by the Nitrolux 1000.
3.3.3 Interference Effects
During the second phase of testing, the Nitrolux 1000 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 Nitrolux 1000 response. The interferent
gases were supplied from diffusion tubes (VICI Metronics, Poulsbo, Washington) at concen-
trations of approximately 100 to 300 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
Nitrolux 1000 until a stable reading was achieved. The interferent gas was added to the zero air
flow and supplied to the Nitrolux 1000 until a stable reading was observed (at least 2 minutes).
The Nitrolux 1000 was flushed for at least 2 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 Nitrolux 1000 until a stable reading was achieved. The interferent gas
was added to the NH3 standard for delivery to the Nitrolux 1000 and the process outlined above
was repeated, delivering the 500-ppb NH3 standard for at least 2 minutes between each
interferent gas.
3.3.4 Comparability
The comparability of the Nitrolux 1000 with a standard reference method was established by
comparing the average Nitrolux 1000 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 jUm).(3)
For this test, NH3 samples were collected using a ChemComb Model 3500 Speciation Sampling
Cartridge (Rupprecht & Patashnick Co., East Greenbush, New York). Figure 3-3 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 liters per minute (Lpm) to remove
particulate matter with aerodynamic diameters greater than 2.5 |im. The air was passed through
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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. For Phase I, air flow was controlled using
diaphragm pumps with needle valves. During
Phase n, automated PartisolM 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. This improved the accuracy
of the sampled air volume and also reduced the
overall labor requirements. The samplers had not
been available during Phase I.
To Pump
JL
4
Teflon filter
Denuder
Coating: 1% citric acid
Impactor
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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.
Inlet
Figure 3-3. Reference Method Sampling
Cartridge
Reference samples were collected during the second and third weeks of testing during each
phase. To capture diurnal variations in NH3 concentrations, sampling was conducted on approxi-
mately 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 (2-hour and 4-hour) sampling captured the
midday peaks in NH3 concentrations, whereas the 12-hour sampling captured overnight,
generally low, concentrations. After sampling, the sampling media were retrieved and
transported to the USDA laboratory for extraction and analysis. During Phase I, sampling was
conducted at two locations: the instrument trailer near the Nitrolux 1000 inlet and near the
platform shown in Figure 3-1. Duplicate samples were obtained at each location. Sampling was
conducted daily, Monday through Friday, during the two-week reference sampling period.
During Phase n, the 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. 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.
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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 USDA analyzed the samples 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. The 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 tolerances 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 each phase using a flow meter with a National
Institute of Standards and Technology (NIST)-traceable calibration. The flow rate of each
sampler was checked at the beginning and end of each sampling period using an in-line flow
meter. The flow rate was readjusted if the flow check was not within ± 5% of the nominal flow
rate of 10 Lpm (i.e., 9.5 Lpm to 10.5 Lpm). All calibration results were documented for
inclusion in the verification test data files. 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
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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 FIA. The calibration was acceptable if the coefficient of
determination (r2) of the calibration curve was greater than 0.99. The FIA detection limit (DL)
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; 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 USDA NH3 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. Reference method DLs were determined for each phase and were more than six
times higher than the equivalent FIA DL (0.6 microgram [|ig] NH3 per 20-mL sample).
11
-------
The reference method DLs, reported as NH3 masses, were used to determine the minimum
detectable NH3 concentration for each phase. 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
varies depending on the same 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 2-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 each phase.
4.2.1.1 Phase I
During Phase I of testing, a total of 11 field blanks were collected (10% of reference samples).
The sample cartridges were exposed to ambient air (caps removed) for approximately the time it
would take to connect the cartridges to the pump tubing. The caps were then replaced and the
cartridges handled in the same way as regular reference samples. The average NH3 mass
collected on the field blanks was 5.3 |ig, with a range of 1.5 to 7.0 |ig. This range of collected
NH3 corresponded to 0.5% to 6.5% of the NH3 mass collected on any of the reference samples
on the corresponding days during which the field blanks were collected. Two of the Phase I field
blanks were above 5% of the minimum reference sample mass for that corresponding day. These
field blanks collected 5.6 |ig NH3, which was slightly above the average field blank NH3 mass
during Phase I; however, the field blanks were collected on days that exhibited lower ambient
NH3 levels, resulting in a relatively large percentage of the reference mass (6.5% and 5.9%).
These field blanks did not show unusually high levels of contamination, and it does not appear
that they had a significant impact on the Phase I reference method results. The standard
deviation of the NH3 collected on field blanks for Phase I was 1.6 |ig and the Phase I reference
method DL was 10.1 jug NH3. The minimum detectable ambient NH3 concentrations are shown
in Table 4-1 for 2-, 4-, and 12-hour samples. During Phase I, all measured NH3 levels were
greater than these minimum NH3 concentrations, with a minimum measured value of 107 ppb
for a 2-hour sample.
Table 4-1. Minimum Detectable Ambient NH3 Concentrations During Phase I
2-Hour
4-Hour
12-Hour
Sample
Sample
Sample
Minimum detectable NH3 concentration
12.1 ppb
6.0 ppb
2.0 ppb
Number of reference samples collected
46
45
19
Number less than the minimum
0
0
0
detectable NH3 concentration
4.2.1.2 Phase II
During Phase II of testing, the reference sampling was conducted somewhat differently than in
Phase I, in that all the reference sampling cartridges and field blanks were installed in the
12
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sampler prior to the first sampling period on a given day. The reference sample and field blank
cartridges were thus exposed to the ambient environment for a period of approximately 24
hours. Nonetheless, the average measured NH3 mass in the field blanks for Phase II was
somewhat lower than in Phase I. 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 2-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 corresponds 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 jug, which
resulted in a 6.6 |ig 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 4-2. During Phase n, one measured NH3 concentration in ambient air fell below the
minimum detectable NH3 concentration, as summarized in Table 4-2.
Table 4-2. 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
4.2.2.1 Phase I
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. Owing to the high NH3 levels
observed during Phase I, all reference samples collected during Phase I included at least one
backup denuder, and most samples (>70%) included two backup denuders. These backup
denuders were used to check the degree of NH3 breakthrough. The breakthrough checks were
conducted at both of the sampling locations and included checks during each of the five
13
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250%
200%
150%
~ 2 Hour Denuder 2
o 2 Hour Denuder 3
a 4 Hour Denuder 2
a 4 Hour Denuder 3
¦ 12 Hour Denuder 2
~ 12 Hour Denuder 3
m
£ 100%
m
50%
9 ~
0%
p s <> \
A
-O O-
0 200 400 600 800 1000 1200 1400 1600 1800
Integrated Ammonia Concentration (ppb)
Figure 4-1. Denuder Breakthrough During Phase I as a Function of Integrated
NH3 Concentration
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 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). This figure illustrates that
the first backup denuder captured a significant fraction of NH3 relative to the front denuder
during many of the sampling periods (up to 200% of the front denuder). The second backup
denuder captured more than 10% of the NH3 on the front denuder in only three cases. It is
unlikely that NH3 was lost due to breakthrough of the second backup denuder for these or any of
the reference samples. Therefore, these samples were not eliminated from the reference data. The
relatively high collection of NH3 on the first backup denuder may have been caused by
displacement by species with a higher affinity for the citric acid coating. Presumably these
species would remain on the front denuder, so it is unlikely that NH3 was lost as a result. Table
4-3 summarizes the results of the breakthrough checks for Phase I.
4.2.2.2 Phase II
The NH3 levels measured during Phase II were significantly lower than observed during Phase I.
Thus, the sampling approach was changed such that all samples still included one backup
denuder but only 19% of the samples collected during Phase II included two backup denuders.
Figure 4-2 shows the percentage of NH3 collected on the backup denuders relative to the front
denuder as a function of the average NH3 concentration during the corresponding sampling
14
-------
Table 4-3. Denuder Breakthrough Checks During Phase I
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
72
100
80
100
74
Average concentration as
% of concentration on
front denuder
19.4
1.2
42.4
2.5
82.5
6.5
Maximum concentration
as % of concentration on
front denuder
111.0
3.6
199.3
41.7
159.2
28.8
Percent of samples with
breakthrough greater
than 10% of front
denuder
57
0
82
3
100
14
O)
3
O
J*.
ro
a)
m
50
300
240
220
2 Hour Denuder 2
2 Hour Denuder 3
4 Hour Denuder 2
4 Hour Denuder 3
12 Hour Denuder 2
12 Hour Denuder 3
100 150 200 250
Integrated Ammonia Concentration (ppb)
Figure 4-2. Denuder Breakthrough During Phase II as a Function of
Integrated NH3 Concentration
350
15
-------
period, using the same symbols as in Figure 4-1. 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
(Denuder 2 in the legend) 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 4-4 summarizes the results of the breakthrough checks for Phase n.
Table 4-4. 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). These duplicate samples were collected at both of the sampling locations
during Phase I, and only at the trailer location during Phase n, and were collected during each of
the sampling periods. 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.
16
-------
Table 4-5 summarizes the results of the duplicate sampling for both Phases I and n. During
Phase I, a total of 18 sets of duplicate samples were collected. Eight of the duplicate samples
were collected at the sampling location next to the trailer, and the other 10 duplicate samples
were collected at the sampling location next to the platform. For Phase I the duplicate samples
showed absolute RPD values between 0.6% and 22%, and the average RPD was 9%. 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%. Although the average RPD values are compara-
ble in Phases I and n, the absolute differences were significantly smaller during Phase n. For
both phases combined, the absolute RPD for 13 of the duplicate samples exceeded the
acceptance criterion 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.
Table 4-5. Duplicate Reference Method Samples
Phase I Phase II
Absolute
Absolute
RPD
Difference
RPD
Difference
(%)
(PPb)
(%)
(PPb)
Average
9
28
7
5
Maximum
22
109
32
18
Minimum
0.6
1
0.7
0.6
Number of duplicate
samples
18
35
Number with RPD >10%
6
7
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
blind samples.
During Phase I, a total of 31 laboratory blank samples were analyzed. The analytical results from
the laboratory blanks indicated no apparent drift in the calibration of the FIA, and none of the
blank values were greater than 5% of the lowest measured reference sample on that day. (Note:
17
-------
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. Similarly, 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 I, 38 NH4+ blind calibration check samples were prepared from 15 different
standard solutions, ranging in concentration from 0.4 to 8 mg/L NH3. Measured concentrations
for 10 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 1.9% lower than the
delivered concentration. It should be noted that the calibration check samples were prepared
from NH4+ standards that were diluted from a 1,000-mg/L stock solution and that errors may
have occurred during the dilution process. For example, nine of the 10 calibration check samples
that failed were prepared from four different standard solutions. Of these four standard solutions,
a total of 10 samples were submitted to the laboratory for analysis, and 9 of the samples fell
outside the 10% acceptance criterion. Of the 28 additional samples submitted to the laboratory
from the 11 other prepared standard solutions, only one fell outside the 10% acceptance
criterion, and the concentration of that standard solution was near the quantitation limit of the
FIA. As such, it is likely that the preparation of the standard solutions contributed to the failure
of the calibration check samples, rather than the calibration of the FIA.
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.
18
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14
~ Reference Measurement
-1:1 Line
y = 0.989x + 0.000
r2 = 1.000
12
10
8
6
4
2
0
0
2
4
6
8
10
12
14
Standard Ammonia Concentration (ppm)
Figure 4-3. Analysis of Diluted NH3 Standards Using the Denuder Reference
Method
Figure 4-3 shows the measured NH3 captured by the sampling cartridges versus the NH3
delivered during the dilution checks.
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 4-3. 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.
19
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The flow rates of the reference method sampling assemblies were audited once during each
phase of 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 attibutable 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 relative agreement
between the reference samples collected during the gas standard dilution check (performed
between Phases I and n) 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 each phase of the test. The purpose of this TSA was to ensure that
the verification 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.
Observations 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
20
-------
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.
4.5 Data Review
Records generated in the verification test were reviewed before these records were used to
calculate, evaluate, or report verification results. Table 4-6 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 after completion of each phase. A deviation report was filed to address this.
Table 4-6. 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.
NH3 analyzer readings
Vendor or
designee
Data acquisition
system (data logger,
personal computer,
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.
All activities subsequent to data recording were carried out by Battelle.
21
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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 Nitrolux 1000 response to each NH3 gas standard
was calculated according to Equation 1:
%D = A ~ A" x 100 n
xn ^
where x is the average Nitrolux 1000 response to an NH3 gas standard of concentration xn. For
each phase of testing, the RA with respect to all of the gas standards (n) delivered to the
Nitrolux 1000 was calculated using Equation 2:
Average RA = - ^ |%D,\j x 100 ^
5.2 Linearity
Linearity was assessed by a linear regression analysis using the compressed gas standard
concentrations as the independent variable and results from the Nitrolux 1000 as the dependent
variable. Linearity was expressed in terms of slope, intercept, and r2 and was calculated inde-
pendently for each phase of the verification test. 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 Nitrolux
1000 measurements of several NH3 gas standards. The mean and standard deviations of those
readings were calculated. The RSD was then determined as:
22
-------
SD
RSD = ^xlOO
x
(3)
where SD is the standard deviation of the Nitrolux 1000 readings and * is the mean of the
Nitrolux 1000 readings. Precision was calculated independently for each phase of testing and the
overall precision was calculated by averaging the precision for all four check periods.
5.4 Response Time
Response time was assessed in terms of both the rise and fall times of the Nitrolux 1000 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 Nitrolux 1000 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) for the change in NH3 concentration 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 Nitrolux 1000 during each phase of
testing. Response times are reported in 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 (minimum and
maximum) of the readings obtained from the Nitrolux 1000 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 independently during each phase of testing so that up to six NH3
standard and zero readings (Monday, Wednesday, and Friday for two weeks) were used in each
phase. The results of these checks indicate 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 Nitrolux
1000 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 Nitrolux 1000, 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.
23
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5.7 Comparability
Comparability between the Nitrolux 1000 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 Nitrolux 1000 as the dependent variable.
Comparability was expressed in terms of slope, intercept, and r2 and was calculated
independently for each phase of the verification test.
24
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Chapter 6
Test Results
The results of the verification test of the Nitrolux 1000 are presented in this section. The values
presented in this section are based on discrete measurements recorded every 60 seconds by the
Nitrolux 1000.
Meteorological conditions collected using the meteorological monitoring station during Phase I
are presented in Figure 6-1. The ambient data set collected by the Nitrolux 1000 is shown in the
bottom panel, along with the wind direction, wind speed, and ambient temperature data. The
shaded regions indicate the NH3 reference method sampling periods. The average ambient NH3
concentration measured by the Nitrolux 1000 was 563 ppb, with a range of 16 to 8,477 ppb. The
meteorological conditions, which were recorded as 1-hour averages, varied widely over the
duration of Phase I. The average ambient temperature during Phase I of the test was 14°C, with a
range of -4 to 29°C. The average relative humidity was 66%. Winds were predominantly from
400
300
=, 2 200
Q CD
-Q 0)
c 2, 100
"O
CL
CL
"O
20
CL
Reference
Measurement
I Period
Reference
Measurement
Period
6000
4000
2000
9/11103
9/16/03
9/21/03
9/26/03
10/1/03
Date
Figure 6-1. Phase I Meteorological Conditions and Nitrolux 1000
Ambient NH3 Measurements
25
-------
the southeast and northwest, with wind speeds up to 17 miles per hour (6 miles per hour
average). When winds were observed from the southeast, the monitors were exposed to
emissions from the nutrient lagoons, whereas the monitors sampled barn emissions during
periods of northerly winds.
Meteorological conditions during Phase II are presented in Figure 6-2. 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 6-2 shows the Phase II wind direction, wind speed, and
ambient temperature data and the ambient NH3 data set collected by the Nitrolux 1000 (bottom
panel). The shaded region shows the period during which NH3 reference measurements were
conducted. The Nitrolux 1000 NH3 measurements ranged from 4 to 879 ppb during Phase n, and
averaged 88 ppb.
§ 300
¦5 W
e 0 200
Q D)
C 2- 100
^ 0
U
0) 30
0) ^
CL _C
w q. 20
"O E
| 10
a) 30
-i 20
03 ^
10
0 0
i—
-10
800
g- 600
03 ...
c 400
o
E
E 200
<
0
10/21/03 10/26/03 10/31/03 11/5/03 11/10/03 1 1/15/03
Date
Figure 6-2. Phase II Meteorological Conditions and Nitrolux 1000
Ambient NH3 Measurements
Reference Measurement Period
26
-------
6.1 Relative Accuracy
During each phase of the verification test, the Nitrolux 1000 was supplied with compressed NH3
gas standards at several concentrations. The NH3 gas standards were diluted in zero air and
delivered to the inlet of the Nitrolux 1000 at a flow rate of 3 to 5 Lpm. Relative accuracy checks
were conducted once during the first week (Week 1) and again during the last week (Week 4) of
each phase of testing. The results presented here are based on the factory calibration of the
Nitrolux 1000, since calibrations were not performed on the Nitrolux 1000 at either test location.
On-site calibration is part of the typical installation procedure recommended by the vendor, but
an independent NH3 standard was not available during the verification test and, consequently,
the vendor did not conduct on-site calibration.
Figures 6-3 (a, b) and 6-4(a, b) present the NH3 concentrations recorded by the Nitrolux 1000
during the RA checks, along with the nominal NH3 concentration levels supplied to the
Nitrolux 1000 for Phase I and Phase n, respectively. The averages of the measurements at each
nominal NH3 concentration, the calculated %D, and the number of data points are presented in
Tables 6-1 and 6-2, along with the average RA for each phase.
As shown in Table 6-1 for Phase I, the Nitrolux 1000 showed %Ds that ranged from 20% to
34% for the Week 1 RA check (between 300 and 5,000 ppb). The average RA over all the
measurements was 27% during this check. The Nitrolux 1000 %Ds ranged from -21% to -7%
for the Week 4 RA check (between 600 and 10,000 ppb). The average absolute RA over all the
concentration ranges was 10% during the check conducted during the last week. The overall
Nitrolux 1000 Phase I RA (the average of all the %Ds measured during Phase I) was 20%.
As shown in Table 6-2, during the Phase II RA checks (between 300 and 2,000 ppb), the %Ds of
the Nitrolux 1000 ranged from -48% to -41% during the Week 1 RA check and from -54% to
-28% during the Week 4 relative accuracy check. The average RA was 44% during Week 1 and
40%) during Week 4, with a Phase II average RA of 42%.
27
-------
7000
6000
_Q
Q.
Q.
5000
o
H—I
03
CD
O
4000
O 3000
I 2000
1000
•Nitrolux 1000
• Gas Standard Concentration
0 ppb
0:00
5,000 ppb
2,000 ppb
300 ppb ^^^^^J1,000 pjbb
600 ppb
1,000 ppb
600 ppb
3:00 6:00
Elapsed Time (hours)
9:00
12:00
Figure 6-3a. Week 1, Phase I Accuracy Results for the Nitrolux 1000
12000
Nitrolux 1000
10,000 ppb
10000
Gas Standard Concentration
¦Q
Q.
Q.
8000 -
c
o
H—<
2
H—<
c
CD
O
c
6000 -
5,000 ppb
o
O
TO
C
o
E
E
<
4000
2,000 ppt
2000 -
1,500 ppl
1,000 ppl
300 ppb 600 ppb.
0 ppb
0:00
1:00
2:00
3:00
4:00
Elapsed Time (hours)
Figure 6-3b. Week 4, Phase I Accuracy Results for the Nitrolux 1000
28
-------
2500
—•—Nitrolux 1000
Gas Standard Concentration
2,000 ppb
2000 -
¦Q
Q.
Q.
c
o
1,500 ppb
H—<
2
H—<
c
1500 -
CD
O
c
o
« 1000 -
1,000 ppb
c
o
E
E
<
600 ppb
500 -
300 ppb
0 ppb
0 4-*
0:00
0:30
1:00
1:30
Elapsed Time (hours)
Figure 6-4a. Week 1, Phase II Accuracy Results for the Nitrolux 1000
2500
— Nitrolux 1000
Gas Standard Concentration
2000 -
¦Q
Q.
Q.
2,000 ppb
C
o
1,500 ppb
H—I
03
s_
H—'
c
1500 -
CD
O
c
o
« 1000 -
1,000 ppb
c
o
E
E
<
600 ppb
500 -
300 ppb
0 ppb
0:00
1:00
2:00
3:00
4:00
5:00
Elapsed Time (hours)
Figure 6-4b. Week 4, Phase II Accuracy Results for the Nitrolux 1000
29
-------
Table 6-1. Relative Accuracy Results During Phase I
Week 1
Week 4
NH3 Gas
Average
Average
Standard
Measured
Number
Measured
Number of
Concentration
Concentration
of Data
%D
Concentration
Data
%D
(PPb)
(PPb)
Points
(%)
(PPb)
Points
(%)
0
13
20
NA
26
10
NA
300
359
20
20
(a)
600
727
20
21
556
10
-7
1,000
1,236
20
24
900
10
-10
1,500
(b)
1,369
10
-9
2,000
2,520
20
26
1,835
10
-8
5,000
6,267
20
25
4,605
10
-8
10,000
(b)
7,924
10
-21
1,000
1,319
20
32
(b)
600
806
20
34
(b)
300
392
9
30
(b)
Average RA
27%
10%
Overall Phase IRA 20%
Gas standard not delivered for a sufficient amount of time to reach a stable reading.
(b) The concentration levels and sequence of NH3 concentrations supplied to the Nitrolux 1000 were changed for the
RA checks conducted during each phase. Consequently, not all concentration levels were measured during both
RA checks.
NA = not applicable.
30
-------
Table 6-2. Relative Accuracy Results During Phase II
Week 1
Week 4
NH3 Gas
Average
Average
Standard
Measured
Number of
Measured
Number
Concentration
Concentration
Data
%D
Concentration
of Data
%D
(PPb)
(PPb)
Points
(%)
(PPb)
Points
(%)
0
6
5
NA
5
10
NA
300
157
10
-48
139
20
-54
600
330
10
-45
280
20
-53
1,000
564
10
-44
716
20
-28
1,500
864
10
-42
956
20
-36
2,000
1,172
10
-41
1,417
20
-29
Average RA
44%
40%
Overall Phase IIRA 42%
NA = not applicable.
6.2 Linearity
Figures 6-5 a and 6-5b show the results of the linearity check for Week 1 and Week 4 of Phase I,
respectively. During Week 1 of Phase I, a linear regression of the Nitrolux 1000 response versus
the gas standard concentration, over the range from 0 to 5,000 ppb, showed a slope of 1.25
(± 0.02), an intercept of 13.2 ppb (± 34.1) ppb, and an r2 of 0.9997, where the numbers in paren-
theses represent the 95% CI. During Week 4 of Phase I, a linear regression of the Nitrolux 1000
response versus the gas standard concentrations over the range from 0 to 10,000 ppb showed a
slope of 0.798 (± 0.071), an intercept of 167 ppb (± 310) and an r2 value of 0.9940. However, as
shown in Figure 6-5b, if the highest concentration value is not included (since it is above the
Nitrolux 1000 measurement range), the linear regression shows a slope of 0.919 (± 0.013), an
intercept of 2.02 ppb (± 29.3), and an r2 value of 0.9999.
Figures 6-6a and 6-6b show the results of the linearity checks for Week 1 and Week 4 of Phase
n, respectively. The linear regression of the Nitrolux 1000 response versus the gas standard
concentration for Week 1 of Phase II, showed a slope of 0.586 (± 0.022), an intercept of
-12.2 ppb (± 24.9), and an r2 of 0.9993. The linear regression results from Week 4 of Phase n,
showed a slope of 0.716 (± 0.121), an intercept of -58.5 ppb (± 137), and an r2 of 0.9854
The results presented here are based on the factory calibration of the Nitrolux 1000, since no
calibrations of the Nitrolux 1000 were performed in the field. Typically, on-site calibrations are
included in the Nitrolux 1000 installation procedure.
31
-------
7000
~ Measurement Data
0 1000 2000 3000 4000 5000 6000 7000
Ammonia Gas Standard Concentration (ppb)
Figure 6-5a. Nitrolux 1000 Linearity Check During Week 1
of Phase I
10000
¦Q
Q.
Q.
¦2 8000
fo
CD
O
c
o
O
¦O
CD
tn
ro
CD
CD
O)
2
CD
>
<
6000
4000
2000 -
+ Measurement Data
0 - 10,000 ppb
X Measurement Data
0 - 5,000 ppb
1:1 Line
0 to 10,000 ppb
y = 0.798X+ 167
r2 = 0.9940
0 to 5,000 ppb
y = 0.919X + 2.02
r2 = 0.9999
0 2000 4000 6000 8000 10000
Ammonia Gas Standard Concentration (ppb)
Figure 6-5b. Nitrolux 1000 Linearity Check During Week 4
of Phase I
32
-------
2000 -
_Q
Q.
Q.
CD
O
C
o
O
"O
(r>
03
CD
CD
O)
03
i_
CD
>
<
1500 -
1000 -
500 -
+ Measurement Data
1:1 Line
y = 0.586x- 12.2
r2 = 0.9993
0 500 1000 1500 2000
Ammonia Gas Standard Concentration (ppb)
Figure 6-6a. Nitrolux 1000 Linearity Check During Week 1
of Phase II
2000 -
+ Measurement Data
1:1 Line
S 1500 -
a) 500
y = 0.716x - 58.5
r2 = 0.9854
500
1000
1500
2000
Ammonia Gas Standard Concentration (ppb)
Figure 6-6b. Nitrolux 1000 Linearity Check During Week 4
of Phase II
33
-------
6.3 Precision
Tables 6-3 and 6-4 present the calculated precision of the Nitrolux 1000 measured during the
accuracy and linearity checks during Phase I and Phase n, respectively. During Phase I, the
precision of the Nitrolux 1000 readings varied from 0.1% to 0.5% RSD in the first accuracy/
linearity check (Week 1) and from 0.2% to 1.3% RSD in the second check (Week 4). During
Phase II, the precision of the Nitrolux monitor readings ranged from 0.3% to 2.3% during the
first accuracy/linearity check (Week 1) and varied from 1.2% to 1.5% RSD in the second
accuracy/linearity check (Week 4). The average overall precision, calculated by taking the
average of all RSDs from all four check periods, during both phases, was 0.7% RSD.
Table 6-3. Calculated Precision of the Nitrolux 1000 During Phase I
NH3 Gas Standard
Concentration (ppb)
Week 1
Week 4
Average Measured
Concentration (ppb)
RSD
(%)
Average Measured
Concentration
(PPb)
RSD
(%)
300
359
0.2
(a)
600
727
0.2
556
0.9
1,000
1,236
0.1
900
0.5
1,500
(b)
1,369
0.6
2,000
2,520
0.4
1,835
0.4
5,000
6,267
0.1
4,605
0.2
10,000
(b)
7,924
1.3
1,000
1,319
0.1
(b)
600
806
0.2
(b)
300
392
0.5
(b)
Average RSD
0.2
0.6
{!i> Gas standard not delivered for a sufficient amount of time to reach a stable reading.
(b:i The concentration levels and sequence of NH3 concentrations supplied to the Nitrolux 1000 were changed for the
RA checks conducted during each phase. Consequently, not all concentration levels were measured during both
RA checks.
34
-------
Table 6-4. Calculated Precision of the Nitrolux 1000 During Phase II
Week 1
Week 4
NH3 Gas Standard
Concentration
(PPb)
Average Reading
(PPb)
RSD
(%)
Average Reading
(PPb)
RSD
(%)
300
157
2.3
139
1.5
600
330
0.3
280
1.2
1,000
564
0.4
716
1.2
1,500
864
0.7
956
1.3
2,000
1,172
1.5
1,417
1.3
Average RSD
1.0
1.3
6.4 Response Time
Response time was determined during each phase from the amount of time required for the
Nitrolux 1000 to reach 95% of the change in stable concentrations during the accuracy/linearity
checks. Table 6-5 presents a summary of the response time determinations for the Nitrolux
1000. Rise times during Phase I ranged from 54 to 1,893 seconds, with fall times between 54
and 214 seconds. Response times measured during Phase II were in approximately the same
range as during Phase I. Phase II rise times ranged from 108 to 1,808 seconds and measured fall
times were 108 and 231 seconds. It should be noted that the response times include the time
associated with equilibration of NH3 on the tubing and inlet surfaces during delivery of the gas
standards.
6.5 Calibration and Zero Drift
The calibration/zero drift checks were conducted by supplying a 1,000 ppb NH3 (nominal) gas
standard and zero air to the Nitrolux 1000 on Monday, Wednesday, and Friday during the first
and last week of each phase. The results of the calibration and drift checks during Phase I and
Phase II are summarized in Tables 6-6 and 6-7, respectively. The values reported in these tables
for the calibration drift checks are based on the average readings during the delivery of the
1000-ppb NH3 gas standard when the readings of the Nitrolux 1000 had stabilized (i.e., the
signal was neither visibly increasing nor decreasing); thus, the calculations for each check span
somewhat different time periods that ranged from 4 to 55 minutes in Phase I and 5 to 65 minutes
in Phase n. During the zero drift checks, although it was not apparent while the checks were
being performed, the Nitrolux 1000 response was still decreasing at the end of each zero air
delivery period, even after delivery durations of 60 minutes. The one exception to this is the first
35
-------
Table 6-5. Response Time Determinations
Phase I
Phase II
Change (ppb)
Rise Time
(seconds)
Fall Time
(seconds)
Rise Time
(seconds)
Fall Time
(seconds)
0-300
183
—
277W
1,808®
—
300 - 600
1,893®
—
229(a)
532
—
600 - 1,000
380(a)
489
—
261
—
1,000 - 1,500
328
—
17 3(a)
108
—
1,000 - 2,000
—
1,500 - 2,000
499
—
167
—
2,000 - 5,000
123
—
(d)
5,000- 10,000
54
—
(d)
10,000-0
—
113
(d)
5,000- 1,000
—
54
(d)
2,000- 1,000
(d)
—
108
2,000 - ambient(e)
(d)
—
231
1,000-600
—
107
(d)
600 - 300
—
214
(d)
(a) For concentration changes that were repeated during Weeks 1 and 4 (for both phases), both values are reported.
(b:i For this transition, there was an initial sharp increase in response, followed by a steady rise until the readings
stabilized.
(c:i Zero air was inadvertently delivered briefly between the two NH3 standards; no response time is reported.
(d:i Not measured since the sequence of NH3 concentrations supplied to the Nitrolux 1000 was different for the two
phases.
(e:i Ambient NH3 concentration was ~80 ppb.
zero check of Phase n, during which a stable response of 2.6 ppb was achieved. For the other
checks, the mean values reported in Tables 6-6 and 6-7 do not represent stable responses, which
may have been reached with longer zero air delivery periods. The values reported for all zero
drift checks were calculated from data for the last 5 minutes of each zero air delivery period. No
obvious drift in the response to zero air was apparent during Phase I or Phase n. The response to
the 1,000 ppb NH3 gas standard increased by approximately 44% during Week 1 of Phase I, but
no drift was apparent during Week 4. No obvious calibration drift was observed during Week 1
or Week 4 of Phase n, but a decrease of approximately 13% was observed between the average
Week 1 and Week 4 responses to a 1,000-ppb NH3 standard. The average response to the
1,000 ppb NH3 gas standard (the average of the values from each phase) decreased from
961 ppb during Phase I to 511 ppb during Phase n.
36
-------
Table 6-6. Calibration and Zero Checks During Phase I
Zero Check
Calibration Check(a)
Min-
Max-
Number of
Min-
Max-
Number of
Check
Mean
SD(b)
imum
imum
Data
Mean
RSD
imum
imum
Data
Number
(ppb)
(ppb)
(ppb)
(ppb)
Points
(ppb)
(%)
(ppb)
(ppb)
Points
Week 1
Monday
13.6
0.9
12.8
15.1
5
865
0.1
864
866
4
Week 1
Wednesday
7.8
0.2
7.7
8.2
5
1,004
0.9
993
1,016
5
Week 1
Friday
9.5
0.3
9.1
10.0
5
1,247
1.3
1,217
1,274
20
Week 4
Monday
4.3
0.3
3.9
4.5
5
892
2.1
861
916
55
Week 4
Wednesday
9.5
0.1
9.4
9.6
5
911
1.5
880
935
54
Week 4
Friday
4.7
0.1
4.7
4.8
5
845
1.4
830
866
49
(a) 1,000 ppb NH3 nominal concentration.
(b) Standard deviation reported for zero drift since the RSD is not meaningfiil for near-zero values.
Table 6-7. Calibration and Zero Checks During Phase II
Zero Check
Calibration Check(a)
Min-
Max-
Number of
Min-
Max-
Number of
Check
Mean
SD(b)
imum
imum
Data
Mean
RSD
imum
imum
Data
Number
(ppb)
(ppb)
(ppb)
(ppb)
Points
(ppb)
(%)
(ppb)
(ppb)
Points
Week 1
Monday
2.6
0.0
2.5
2.6
5
(<0
Week 1
Wednesday
2.0
0.3
1.7
2.4
5
567
1.5
554
581
45
Week 1
Friday
2.4
0.1
2.3
2.6
5
542
1.7
525
561
56
Week 4
Monday
3.5
0.2
3.2
3.8
5
479
1.5
468
493
52
Week 4
Wednesday
2.2
0.2
1.9
2.3
5
486
1.6
470
500
51
Week 4
Friday
5.3
0.2
5.1
5.5
5
480
1.3
469
490
41
(a) 1,000 ppb NH3 nominal concentration.
(b) Standard deviation reported for zero drift since the RSD is not meaningfiil for near-zero values.
(c) NH3 gas standard not delivered for a sufficient amount of time to reach a stable reading.
37
-------
6.6 Interference Effects
The effect of potential interferent gases on the response of the Nitrolux 1000 was assessed by
supplying the Nitrolux 1000 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
Nitrolux 1000 during the introduction of these gases is summarized in Table 6-8. The interferent
gas concentrations carry an uncertainty of approximately ±15% (as reported by the manufacturer
for uncertified permeation tubes).
The response of the Nitrolux 1000 to hydrogen sulfide, nitrogen dioxide, and 1,3-butadiene was
negligible. The Nitrolux 1000 showed no significant response to diethylamine in a 500-ppb NH3
standard, but an interference effect of 19% to diethylamine was observed in zero air. However,
the presence of an NH3 impurity in the diethylamine standard or the release of NH3 from the
sample lines during delivery could not be ruled out.
Table 6-8. Interference Effect Evaluation
Interference Effect (%)
Interferent Gas
Concentration
Gas (ppb) Zero-Air Matrix 500-ppb NH3 Matrix
Hydrogen sulfide 285
Nitrogen dioxide 95
1,3-Butadiene 95
Diethylamine 96
(a) Signal not significantly different from baseline without interferent gas.
(b) Noise introduced from testing activities prevented reliable quantification of the interference from these compounds. However,
no significant response was observed.
(c) The presence of an NH3 impurity in the diethylamine gas standard or the release of NH3 from the sample lines during delivery
could not be ruled out.
0(a)
0.4(a)
0.8(a)
19(c)
0.1(a)
l.l(a)
(b)
(b)
6.7 Comparability
Figures 6-7 and 6-8 show the NH3 concentrations measured using the reference method, along
with the corresponding average readings of the Nitrolux 1000 for the reference sampling
periods, during Phase I and Phase n, respectively. In general, the Nitrolux 1000 appeared to
track changes in NH3 concentrations measured with the reference method. These data also are
presented in Figures 6-9 and 6-10 as scatter plots to illustrate the correlation between the
reference and Nitrolux 1000 data.
38
-------
3000
Reference
Original Nitrolux
Corrected Nitrolux
2500
.Q
Q.
Q.
o 2000
"S
•*—I
c
O 1500
c
o
O
CO
'c
o
E
E
<
1000
500
f1,nn,nP,
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
CO
o
O
O
O
O
O
o
o
o
o
o
o
LO
CD
CO
CD
O
T—
CNJ
CO
LO
CD
T—
—
t—
T—
T—
OJ
OJ
OJ
OJ
OJ
OJ
OJ
CD
CD
CD
CD
CD
o5
o5
o5
o5
CD
o5
o5
O
O
O
O
O
o
o
o
o
o
o
o
Date
Figure 6-7. Comparison of Ambient Reference Measurements with Averages from
the Nitrolux 1000 During Phase I
400
.Q
A 300
Reference
Original Nitrolux
Corrected Nitrolux
® 200
Date
Figure 6-8. Comparison of Ambient Reference Measurements with Averages from
the Nitrolux 1000 During Phase II
39
-------
3000 -
2500
Q_
C
o
2 2000
-i—<
c
CD
O
£=
O 1500
£=
O
D)
to
1000 -
500 -
~
O
Original Data
Corrected Data
-1:1 Line
Original Data
y= 1.83X + 4.77
r2= 0.9842
Corrected Data
y= 1.46X-6.7
r2 = 0.9842
500 1000 1500 2000 2500
Reference Ammonia Concentration (ppb)
3000
Figure 6-9. Scatter Plot of Averages from the Nitrolux 1000
versus Ambient Reference Measurements During Phase I
350 -
_Q
a 300
o
'¦4—'
c
CD
O
c
o
O
X
o
250 -
200 -
150 -
o
100
a3
>
<
50 -
~
Original Data
o
Corrected Data
— 1:1 Line
Original Data
= 0.646x + 0.432
r2 = 0.9794
Corrected Data
y = 1.1 Ox + 21.6
i2 = 0.9794
0 50 100 150 200 250 300 350
Reference Ammonia Concentration (ppb)
Figure 6-10. Scatter Plot of Averages from the Nitrolux
1000 versus Ambient Reference Measurements During
Phase II
40
-------
The Phase I Nitrolux 1000 average readings were consistently higher than the reference method,
while during Phase II the Nitrolux 1000 readings were consistently lower than the reference
method results. However, during both phases, the Nitrolux 1000 average readings and the
reference method results were highly correlated.
A linear regression of the Nitrolux 1000 responses during the reference sampling periods versus
the NH3 determined from the reference method was calculated for each phase. For Phase I, the
linear regression results showed a slope of 1.83 (± 0.07), an intercept of 4.77 ppb (±34.01), and
an r2 value of 0.9842, where the numbers in parentheses represent the 95% CI. For Phase n, the
linear regression results showed a slope of 0.646 (± 0.03), an intercept of 0.432 ppb (± 4.10),
and an r2 value of 0.9794. Since no calibration was performed on-site during either phase of the
verification test, these results are based on the factory calibration of the Nitrolux 1000. In the
absence of an on-site calibration, the results of the first linearity checks conducted during each
phase can be used to apply calibration corrections to the Nitrolux 1000 data. If such a calibration
correction were applied to the data used to establish comparability, the results of the linear
regression for Phase I would show a slope of 1.46 (±0.06), an intercept of -6.7 (±27.2), and an r2
of 0.9842. Similarly, the results of the linear regression for Phase II would show a slope of 1.10
(±0.06), an intercept of 21.6 (±7.0), and an r2 of 0.9794. The corrected Nitrolux 1000 measure-
ments are also shown in Figures 6-7, 6-8, 6-9, and 6-10.
6.8 Ease of Use
The Nitrolux 1000 was installed at the Phase I and Phase II testing locations by the vendor
representative. The Nitrolux 1000 could be installed and operated by a user with minimal
experience and the Nitrolux 1000 manual. Although the Nitrolux 1000 was not calibrated on-site
with an NH3 gas standard during this test, a gas phase calibration is generally included in the
installation procedure. The installation took less than one day. A checklist was provided by the
vendor representatives to establish whether the instrument was in proper working order. The
checklist, shown in Appendix A, was completed by Battelle or USDA staff during daily checks
of the Nitrolux 1000 operating status. No routine maintenance was required for the
Nitrolux 1000. The vendor representative replaced the inlet particulate filter before
each phase of testing.
The Nitrolux 1000 was very easy to operate. The software was very user-friendly, automatically
rebooted the PC on a daily basis, and accounted for daylight savings time without intervention.
The system was found to not be responding once during each phase; once the operator rebooted
the computer, the Nitrolux 1000 resumed measurements without further input. The Nitrolux
1000 software displayed a 4- or 8-hour record of NH3 measurements, which were updated in real
time. Data were automatically saved as text files containing the time and NH3 concentration at a
frequency of approximately one point per minute. New files were saved for each day of the
verification test, each with approximately 25 kilobytes of data. The full data set for each 4-week
phase was approximately 800 kilobytes in size. The personal computer stored all of the measure-
ment data, which could be downloaded to a USB "thumb drive" (supplied by the vendor). Once
the thumb drive was plugged into the personal computer, the data were automatically down-
loaded to the device without operator prompt or intervention. A summary of the activities
41
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performed to the Nitrolux 1000 during Phase I and Phase II are presented in Tables 6-9 and 6-
10, respectively.
Table 6-9. Activities Performed During Phase I
Date
Time
Offline (a)
(minutes)
Down
Time (b)
(minutes)
Service
Time (c)
(minutes)
Activity
9/08/03
45
Supplied zero air and NH3 standard®
9/10/03
130
Supplied zero air and NH3 standard®
9/11/03
270
Supplied zero air and NH3 standards®
9/12/03
120
Supplied zero air and NH3 standard®
9/13/03
250
Supplied zero air and NH3 standards®
9/16/03
340
5
System stopped responding overnight.
Rebooted computer.
9/17/03
120 (e)
Power loss. Instrument recovered
without user intervention.
9/29/03
145
Supplied zero air and NH3 standard®
9/30/03
240
Supplied zero air and NH3 standards®
10/01/03
120
Supplied zero air and NH3 standard®
10/03/03
120
Supplied zero air and NH3 standard®
Totals
1,440
340(e)
5
99% data completeness® and 5-minute
service time.
(^ Time Offline = time that the Nitrolux 1000 was taken offline for zero or standard gas measurements. The period
over which time offline was evaluated began at 8:00 a.m. on 9/8/03 and ended at the conclusion of testing at
5:00 p.m. on 10/3/03. The amount of time was rounded to the nearest 5 minutes.
(b:i Down Time = time that the Nitrolux 1000 was not operating or was operating but not reporting reliable
measurements. The period over which down time was evaluated began at 8:00 a.m. on 9/8/03 and ended at the
conclusion of testing at 5:00 p.m. on 10/3/03. The amount of time was rounded to the nearest 5 minutes. Down
time that did not result in loss of data is not included in the availability determination.
(c:i Service Time = time spent conducting routine operation and maintenance activities and troubleshooting problems.
The period over which service time was evaluated began at 8:00 a.m. on 9/8/03 and ended at the conclusion of
testing at 5:00 p.m. on 10/3/03. The amount of time was rounded to the nearest 5 minutes.
(d:i Testing activity performed by Battelle/USDA operator.
(e:i The 120-minute down time that resulted from the absence of power at the test site was not included in the down
time calculation as it does not reflect on the performance of the Nitrolux 1000.
® Data Completeness = the ratio of time that the Nitrolux 1000 was not experiencing down time to the total time
available for monitoring ambient NH3 mixing ratios from the start of testing on 9/8/03 to the end of testing on
10/3/03. The total time that was available for monitoring was 36,540 minutes or 609 hours.
6.9 Data Completeness
The Nitrolux 1000 was operating and collecting data for 99% of the available time during both
Phase I and Phase n. As discussed in Section 6.8, the 1% data loss was attributed to
software/computer failures.
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Table 6-10. Activities Performed During Phase II
Date
Time
Offline (a)
(minutes)
Down
Time (b)
(minutes)
Service
Time (c)
(minutes)
Activity
10/20/03
260
Delivered zero air and NH3 standard®
10/22/03
110
Delivered zero air and NH3 standard®
10/23/03
90
Delivered zero air and NH3 standards®
10/24/03
120
Delivered zero air and NH3 standard®
10/26/03
System automatically adjusted time for
daylight savings.
10/30/03
350
5
System stopped responding overnight.
Rebooted computer.
11/10/03
120
Delivered zero air and NH3 standard®
11/11/03
535
Performed interference tests®
11/12/03
120
Delivered zero air and NH3 standard®
11/14/03
470
Delivered zero air and NH3 standards®
Totals
1,825
350
5
99% data completeness^-1 and 5-minute
service time.
(a) Time Offline = time that the Nitrolux 1000 was taken offline for zero or standard gas measurements. The period
over which time offline was evaluated began at 8:00 a.m. on 10/20/03 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 Nitrolux 1000 was not operating or was operating but not reporting reliable
measurements. The period over which down time was evaluated began at 8:00 a.m. on 10/20/03 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.
(c) Service Time = time spent conducting routine operation and maintenance activities and troubleshooting problems.
The period over which service time was evaluated began at 8:00 a.m. on 10/20/03 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 Completeness = the ratio of time that the Nitrolux 1000 was not experiencing down time to the total time
available for monitoring ambient NH3 mixing ratios from the start of testing on 10/20/03 to the end of testing on
11/14/03. The total time that was available for monitoring during Phase 2 was 35,280 minutes or 588 hours.
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Chapter 7
Performance Summary
The performance of the Nitrolux 1000 was evaluated in two phases in this verification test.
Table 7-1 presents a summary of the performance of the Nitrolux 1000 NH3 during this
verification test.
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Table 7-1. Nitrolux 1000 Performance Summary
Results
Phase I
Phase II
Parameter
Week 1
Week 4
Week 1
Week 4
Relative
accuracy(a-l(b-1
Average RA
%D range
27%
20 to 34%
10%
-21 to -7%
Average RA
%D range
44%
-48 to -41%
40%
-54 to -28%
Linearity1-3-1
Range
Slope
Intercept
r2
0 to 5,000 ppb
1.25 (±0.02)
13.2 ppb (±34.1)
0.9997
0 to 10,000 ppb
0.798 (±0.071)(c)
167 ppb (±310)
0.9940
Range
Slope
Intercept
r2
0 to 2,000 ppb
0.586 (±0.022)
-12.2 ppb (±24.9)
0.9993
0 to 2,000 ppb
0.716 (±0.121)
-58.5 ppb (±137)
0.9854
Precision1-3-1
Average RSD
Range
0.2%
0.1 to 0.5%
0.6%
0.2 to 1.3%
Average RSD
Range
1.0%
0.3 to 2.3%
1.3%
1.2 to 1.5%
Response time
Rise time = 54 to 1,893 seconds
Fall time = 54 to 214 seconds
Rise time = 108 to 1,808 seconds
Fall time = 108 to 231 seconds
Calibration/
zero drift
¦ No apparent drift in response to zero air during
Week 1 or Week 4.
¦ Apparent drift of approximately 44% in response to
1,000 ppb NH3 observed during Week 1. No
apparent drift observed during Week 4.
¦ No apparent drift in response to zero air during
Week 1 or Week 4.
¦ Apparent drift of approximately 13% in response to
1,000 ppb NH3 between Week 1 and Week 4.
Interference
effects®
Interference check conducted during Phase II.
¦ Hydrogen sulfide (285 ppb): no apparent effect
¦ Nitrogen dioxide (95 ppb): no apparent effect
¦ 1,3-Butadiene (95 ppb): no apparent effect
¦ Diethylamine (96 ppb): -19% response in zero air,
no apparent effect in 500 ppb NHj1-6-1
Raw Data(a)
Corrected Data®
Raw Data(a)
Corrected Data®
Comparability
Slope
Intercept
r2
1.83 (±0.07)
4.77 (±34.01)
0.9842
1.46 (±0.06)
-6.7 (± 27.2)
0.9842
Slope
Intercept
r2
0.646 (±0.03)
0.43 (±4.1)
0.9794
1.10 (±0.06)
21.6 (±7.0)
0.9794
Ease of use
¦ Daily checks were simple and quick
¦ Little skill required to operate
¦ No maintenance required
¦ User-friendly software
Data
completeness
99%
99%
Results based on Nitrolux 1000 factory calibration since an on-site calibration was not performed. On-site calibration is
generally included in Nitrolux 1000 installation procedures, but an independent NH3 standard was not available during the
verification test.
(b) Relative accuracy is expressed as an average absolute value of the percent difference from NH3 gas standards.
(c) Including only data fromO to 5,000 ppb, the slope was 0.919 (±0.013), with an intercept of-12.8 (±34.4) and an r2 of 0.9998.
The linear range for the Nitrolux 1000 is reported to be 0 - 2,000 ppb by the manufacturer.
(d) Calculated as the change in signal divided by the interferent gas concentration, expressed as a percentage.
® The presence of an NH3 impurity in the diethylamine gas standard or the release of NH3 from the sample lines during delivery
could not be ruled out.
(f) Results of Week 1 linearity check were used to apply a calibration correction to the Nitrolux 1000 ambient data.
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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
Nitrolux 1000 Checklist
A-l
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ETV Verification of Ambient Ammonia Monitors
Pranalytica Nitrolux 1000 Ambient Ammonia Analyzer
Daily Checklist
Vendor Contact Information
Operational Instructions:
1. Use the touchpad to "wake up" screensaver
2. Observe that readings have been continuous over the last 4 or 8 hours ~
3. Record the following readings
a. Pressure
b. Flow (Normal range is 400-500 seem. If flow is steady at
350 seem, change inlet filter)
c. Cell Temp
d. Laser Temp
4. Are all warning lights green? (Contact Pranalytica if not)
5. Is the timestamp of display and screen the same as LCD?
Signature
Date
Comments:
A-2
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