United States
Environmental Protection
Agency
Environmental Monitoring SystemsvC;
Laboratory
Research Triangle Park NC 2771 T V« »
Research and Development
EPA-600/S4-83-019 June 1983
Project Summary
Performance Test Results and
Comparative Data for Designated
Reference and Equivalent
Methods for Nitrogen Dioxide
R M. Michie, Jr., F. F. McElroy, J. A Sokash, V. L Thompson, and B. P. Fritschel
This report summarizes the results
of postdesignation testing (both la-
boratory and field) conducted on 10
commercially available ambient nitro-
gen dioxide analyzers to characterize
their performance, reliability, and op-
erational peculiarities.
This Project Summary was developed
by EPA's Environmental Monitoring
Systems Laboratory, Research Triangle
Park. NC, to announce key findings of
the research project that is fully doc-
umented in a separate report of the
same title (see Project Report ordering
information at back).
Introduction
Under Part 53 of Title 40 of the Code of
Federal Regulations (40 CFR Part 53), the
U.S. Environmental Protection Agency
(EPA) designates specific procedures or
analyzers as reference or equivalent meth-
ods for the monitoring of ambient air
pollutants. The methods are then accept-
able for use in National Air Monitoring
Stations (NAMS), State and Local Air
Monitoring Stations (SLAMS), and Preven-
tion of Significant Deterioration (PSD)
monitoring. The Methods Standardization
Branch (MSB) of the Environmental Moni-
toring Systems Laboratory (EMSL) at Re-
search Triangle Park, NC, is responsible
for EPA's reference and equivalent method
designation program. In this capacity,
MSB has acquired performance data and
other information on these methods, most
of which are commercially available ana-
lyzer models.
To summarize these data and make
them available to those who may find them
beneficial in the selection of analyzers,
MSB, with the assistance of the Research
Triangle Institute (RTI), prepared this report
on designated methods for nitrogen dioxide.
Types of Tests Conducted
Two principal types of postdesignation
tests were conducted by MSB. Phase I
tests were laboratory tests similar to the
predesignation tests required by 40 CFR
Part 53. Phase II tests simulated actual
use conditions and compared simulta-
neously operating analyzers. Results from
these postdesignation tests provide most
of the data in this report
Analyzers Tested
The report is intended to cover all cur-
rently designated reference methods for
N02. However, as of this writing, the tests
have not been completed for all analyzers.
Table 1 lists the designated N02 ana-
lyzers, their detection principles, the tests
that have been carried out and the dates of
the tests.
Phase I Test Description and
Results
Phase I laboratory performance tests
were conducted in accordance with the
same procedures and specifications re-
quired for the applicant's predesignation
tests, with the exception that fewer trials
(usually four) were performed for each test
parameter. All calibrations, apparatus,
pollutant standards, test procedures, test
atmospheres, and test documentation were
as specified in40 CFR Part 53. (Individual
reports containing more detailed informa-
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tion on the Phase I tests for each analyzer
are available from MSB.)
Analyzers undergoing Phase I tests were
allowed to operate for several weeks prior
to actual testing. During this startup
period, preliminary calibration and lineari-
ty checks were performed. If a failure
occurred during testing, the manufacturer
was notified and given the opportunity to
correct the failure At the conclusion of the
tests, all failures and manufacturer's in-
volvement were included in routine docu-
mentation.
Phase I tests included characterization
of output signal noise level, lower detect-
able limit (LDL), interference equivalents,
12-h and 24-h zero drifts, span drift at 20
and 80 percent of full scale, lag time, rise
time, fall time, and precision. Results are
reported in Table 2. The total interferent
equivalent, zero drift, and span drift data
reported are averages of absolute values;
all other values represent the arithmetic
averages of several repetitions.
Phase I results indicated that the six
nitrogen dioxide analyzers tested to date
met or exceeded the performance specifi-
cations. Testing of two analyzers is not
complete at this time.
Phase II Test Description and
Results
The Phase II test was intended to test
the analyzers in a more or less typical
ambient monitoring configuration where
each analyzer's stability, reliability, general
performance, and operational peculiarities
could be observed and compared with
other analyzers. The test was conducted
on a group of nine NO2 analyzers operating
simultaneously over a period of 6 months.
All analyzers measured ambient air sam-
pled from a common manifold
All test analyzers were installed calibrated
operated, and maintained in strict accor-
dance with the manufacturer's instruction
manual and good monitoring practice.
Analyzers received a multipoint calibration
initially and once per month during the test
period. Zero and span checks were made
two or three times per week Zero adjust-
ments were made only if the zero response
was not within ±3 percent of full-scale
response from nominal; span adjustments
were made only if the span (slope of the
calibration curve) changed by more than
±7 percent from nominal. Data were
acquired using a Monitor Labs 9300 Data-
logger data acquisition system. The ac-
quired data were transferred via magnetic
tape to a Hewlett-Packard 9845 Desk Top
Table 1. NO2 Analyzers Tested and Test Dates
Detection
Manufacturer Model principle
Beckman
Bendix
Bendix (# 1)
Bendix (#2)
CSI
Meloy
Monitor Labs
Monitor Labs
Philips
Thermo Electron
Thermo Electron
952A
8101B
8101C
8101C
1600
NA530R
8440E
8840
PW9762/02
14B/E
14D/E
CL
CL
CL
CL
CL
CL
CL
CL
CL
CL
CL
Phase 1 tests
July 1979-December 1980
No postdesignation testing anticipated
February-April 1980
NA
March-September 1980
July 1 979-September 1980
May-October 1980
June -October 1980
No postdesignation testing anticipated
May 1980- January 1981
February-April 1980
Phase II tests
April -September 1981
April -September 1981
June -September 198 1
April -September 1981
June -September 1981
June -September 198 1
April -July 1981
April -September 1981
April -September 1981
NA = Not applicable.
CL = Gas Phase Chemiluminescence.
Table 2. Phase I Postdesignation Test Results-Designated Nitrogen Dioxide Analyzers
Performance
parameters
Noise - 0% URL
Noise - 80% URL
Lower detectable limit
Interferents
NO
S02
NH3
H2O
Total
Zero drift - 12 h
Zero drift - 24 h
Span drift - 20% URL
Span drift - 80% URL
Lag time
Rise time
Fall time
Precision - 20% URL
Precision - 80% URL
EPA
specifications
0.005 ppm
0.005 ppm
±0.02 ppm
±0.02 ppm
±0.02 ppm
±0.02 ppm
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Computer where they were reduced into a
useful form
Phase II results indicated that most of
the nitrogen dioxide analyzers are stable
and reliable. The comparative data pre-
sented in Table 3 indicate high correlation
coefficients between ^ 0.98 and 1.00.
Most are equal to or greater than 0.99.
Mean differences are generally within±1.0
ppb while standard deviations of the dif-
ferences are between 1.0 and 3.0 ppb.
Likewise, the individual analyzer drift re-
sults presented in Table 4 show standard
deviations of zero drifts to be generally
less than 3.0 ppb, averaging 1.5 ppb, and
standard deviations of span drifts to be
generally less than 3.5 percent averaging
2.4 percent
Table3. Summary of Phase II Post designation Test Results for Designated Nitrogen Dioxide Analyzers When Compared to the Average of the Other
Eight Analyzers
Statistics
Correlation coefficient
Mean difference, ppb
Standard deviation of
differences, ppb
Number of absolute
differences > 20 ppb
Number of differences
Beckman
952A
0.995
40.97
1.59
0
2,978
Bendix
8101C
0.996
-0.63
1.27
0
3,014
Bendix
8101C
(COL)
0.993
+0.14
1.47
0
Z090
CSI
1600
0.989
+0.25
2.05
5
3,115
Meloy
NA530R
0.978
+2.18
2.82
0
2,134
Monitor
Labs
8440E
0.994
+0.13
1.30
0
1,047
Monitor
Labs
8840
0.979
-0.48
2.97
0
1.641
Thermo
Electron
14B/E
0.998
-0.42
0.90
0
3,101
Thermo
Electron
14D/E
0.994
-1.25
1.47
0
Z700
COL = Collocated.
Table 4. Phase II Postdesignation Test Results for Drift
Statistics
Standard deviation of
zero drift ppb
Standard deviation of
span drift %
Beckman
952A
1.8
3.4
Bendix
8101C
1.6
1.5
Bendix
8101C
(COL)
0.9
1.6
CSI
1600
0.8
1.6
Meloy
NA530R
3.0
1.6
Monitor
Labs
8440E
1.3
1.0
Monitor
Labs
8840
2.6
2.1
Thermo
Electron
14B/E
0.9
1.8
Thermo
Electron
14D/E
1.1
2.4
COL = Collocated.
Raymond M. Michie. Jr. and. John A. Sokash are with Research Triangle Institute,
Research Triangle Park, NC 27711; Betsy P. Fritschel is presently with First
State Chemical Co., Wilmington, DE.
Frank F. McElroy and Vinson L. Thompson are the EPA Project Officers (see
below).
The complete report, entitled "Performance Test Results and Comparative Data
for Designated Reference and Equivalent Methods for Nitrogen Dioxide," (Order
No. PB83-2OO238; Cost: $ 13.00, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Monitoring Systems Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC
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Agency
Center for Environmental Research
Information
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