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U.S. EPA

Ambient Air Protocol Gas Verification Program
Annual Report, CY 2023


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EPA-454/R-24-007
December 2024

U.S. EPA Ambient Air Protocol Gas Verification Program Annual Report CY 2023

U.S. Environmental Protection Agency
Office of Air Quality Planning and Standards
Air Quality Assessment Division
Research Triangle Park, NC


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Table of Contents

U.S. EPA Ambient Air Protocol Gas Verification Program Annual Report, CY 2023

Acknowledgements
Acronyms and Abbreviations
1.0 Introduction
Background and Program Goals
Purpose of this Document
2.0 Implementation Summary
Producer Information Data Collection
AA-PGVP Verification Dates
Workflow of the AA-PGVP
3.0 Survey and Verification Results
Monitoring Organization Survey
Verification Results
4.0 Summary and Conclusions
General -

Survey Participation -
RAVLs -

Quality System -
Data Management -
Appendix A

QA Reports from Measurement Data Worksheets for 2023

Tables

Table 1. RAVL Verification Dates

Table 2. Gas Standards Sent to RAVLs

Table 3. MQOs for the AA-PGVP

Table 4. AA-PGVP CO and S02 Verifications

Table 5. AA-PGVP NO and NOx Verifications

Figures

Figure 1. AA-PGVP Flowchart
Figure 2. AA-PGVP Annual Survey
Figure 3. Verification Trend

Figure 4. QA SUMMARY FOR TEST NO OF EB0086492 (STD #1)

Figure 5. QA SUMMARY FOR CO TEST OF LL40350 (STD #1)

Figure 6. QA SUMMARY FOR CO TEST OF FF776 (STD #1)

Figure 7. QA SUMMARY FOR NO TEST OF CC697669 (STD #1), CC697663 (STD #2), FF13090 (STD #3)
Figure 8. QA SUMMARY FOR NO TEST OF EX0012199 (STD #1)

1

5

6

7

7

8

9

9

10

10

11

11

12

16

16

16

16

17

17

19

19

10

13

14

15

15

11

12

13

20

21

22

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Acknowledgements

The following individuals and organizations are acknowledged for their contributions to this project:

US EPA, Office of Air Quality Planning and Standards
Douglas Jager

US EPA, Office of Research and Development
Bob Wright (Retired)

US EPA Region 4

Mike Crowe	Keith Harris

US EPA Region 7

Thien Bui	James Regehr

Monitoring Organizations

EPA acknowledges the monitoring organizations that supported the AA-PGVP Annual Survey in CY-2023.
They include:

Al Dept Of Env Mgt

Alaska Department of Environmental Conservation
Albuquerque Environmental Health Department,
Air Quality Division

Arizona Department of Environmental Quality
Broward County Environmental Protection Department
California Air Resources Board
Cherokee Nation, Oklahoma
Clark County, NV DES

Colorado Department of Public Health and Environment

Connecticut Department of Environmental Protection
Florida Department of Environmental Protection (FDEP)
Forsyth County Environmental Affairs Department
Georgia Air Protection Branch Ambient Monitoring
Program

Great Basin Unified APCD

Idaho Department of Health and Welfare-Environment
Division

Illinois Environmental Protection Agency

Indiana Depart of Environ Management/Office of Air

Quality

Jefferson County, AL Department of Health
Kansas Department of Health and Environment

Kentucky Division for Air Quality
Linn County Health Department

Magnitude 7 Metals
Maricopa County Air Quality
Maryland Department of the Environment
Mass Dept Environmental Protection-Div Air
Quality Control

Mecklenburg County Air Quality

Miami-Dade County Department of Environmental

Resources Management

Michigan Dept Of Environment, Great Lakes, and

Energy-Air Quality Division

Mississippi DEQ, Office of Pollution

Missouri Laboratory Services Program

Mojave Desert AQMD

Monterey Bay Unified APCD

New Hampshire Air Resources Agency

New Jersey State Department of Environmental

Protection

New Mexico Environment Department
North Carolina Dept Of Environmental Quality

Ohio EPA, Central District Office

Pima County Department of Environmental
Quality

Polk County Physical Planning
Rhode Island DEM And DOH

Sacramento County APCD

San Diego County Air Pollution Control District

San Luis Obispo County APCD

South Carolina Department Health and

Environmental Control

South Coast Air Quality Management District
State Of Louisiana

Tennessee Division of Air Pollution Control

Texas Commission on Environmental Quality
US EPA - Region 9

University Hygienic Laboratory (University of Iowa)
Ventura County APCD

Vermont Agency Of Environmental Conservation
Virginia Department of Environmental Quality
Washoe County District Health Department
West Virginia Northern Panhandle Regional Office

Wisconsin Dept of Natural Resources, Air
Monitoring Section


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Acronyms and Abbreviations

AA-PGVP

Ambient Air Protocol Gas Verification Program

AMTIC

Ambient Monitoring Technology Information Center

AQS

Air Quality System

CFR

Code of Federal Regulations

CO

Carbon Monoxide

CONC

Concentration

CY

Calendar Year

DoE

Declaration of Equivalence with the National Institute of Standards and Technology

EPA

Environmental Protection Agency

GMIS

Gas Manufacturer's Intermediate Standard

ID

Identification

MFC

Mass Flow Controller

NIST

National Institute of Standards and Technology

NMI

National Metrology Institute

N02

Nitrogen Dioxide

NOx

Nitrogen Oxides

MQO

Measurement Quality Objective

NTRM

NIST Traceable Reference Material

NVLAP

National Voluntary Laboratory Accreditation Program

OAQPS

Office of Air Quality Planning and Standards

OAR

Office of Air and Radiation

OIG

Office of the Inspector General

ORD

Office of Research and Development

PQAO

Primary Quality Assurance Organization

PRM

Primary Reference Material

PSI

Pounds per Square Inch

PSIG

Pounds per Square Inch Gauge

QA

Quality Assurance

QAPP

Quality Assurance Project Plan

QC

Quality Control

QTR

Quarter

RAVL

Regional Analytical Verification Laboratory

RD

Relative Difference

RPD

Relative Percent Difference

SI

International System of Units

S02

Sulfur Dioxide

SOP

Standard Operating Procedure

SRM

Standard Reference Material

URL

Upper Range Limit

VSL

Netherland's National Metrology Institute; Dutch Von Swinden Laboratorium


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1.0 Introduction

Background and Program Goals

The basic principles of the U.S. Environmental Protection Agency's (EPA) Traceability Protocol for the Assay and
Certification of Gaseous Calibration Standards (EPA, 2012)1 were developed jointly by EPA, the National Bureau of
Standards (now National Institute of Standards and Technology [N 1ST]), and specialty gas producers over 40 years ago.
At the time, commercially prepared calibration gases were perceived as being too inaccurate and too unstable for use
in calibrations and audits of continuous source emission monitors and ambient air quality monitors2. The protocol was
developed to improve the quality of the gases by establishing their traceability to NIST Standard Reference Materials
(SRMs) and to provide reasonably priced products. This protocol established the gas metrological procedures for
measurement and certification of these calibration gases for EPA's Acid Rain Program under 40 Code of Federal
Regulations (CFR) Part 75, for the Ambient Air Quality Monitoring Program under 40 CFR Part 58, and for the Source
Testing Program under 40 CFR Parts 60, 61, and 68. EPA required that the monitoring organizations implementing
these programs ("the regulated community") to use EPA Protocol Gases as their calibration gases. EPA revised the
protocol to establish detailed statistical procedures for estimating the total uncertainty of these gases. EPA's Acid Rain
Program developed acceptance criteria for the uncertainty estimate3.

Specialty gas producers prepare and analyze EPA Protocol Gases without direct governmental oversight. In the 1980s
and 1990s, EPA conducted a series of EPA-funded accuracy assessments of EPA Protocol Gases sold by producers. The
intent of these audits was to:

•	increase the acceptance and use of EPA Protocol Gases as calibration gases,

•	provide a quality assurance (QA) check for the producers of these gases, and

•	help users identify producers who can consistently provide accurately certified gases.

Either directly or through third parties, EPA procured EPA Protocol Gases from the producers, assessed the accuracy of
the gases' certified concentrations through independent analyses, and inspected the accompanying certificates of
analysis for completeness and accuracy. The producers were not aware that EPA had procured the gases for these
audits.

The accuracy of the EPA Protocol Gases' certified concentrations was assessed using SRMs as the analytical reference
standards. If the difference between the audit's measured concentration and the producer's certified concentration
was more than ±2.0 percent or if the documentation was incomplete or inaccurate, EPA notified the producer to
resolve and correct the problem. The results of the accuracy assessments were published in peer-reviewed journals
and were posted on EPA's Technology Transfer Network website. The accuracy assessments were discontinued in
1998.

In 2009, the Office of the Inspector General (OIG) published the report EPA Needs an Oversight Program for Protocol
Gases4. One of the report's findings suggested that EPA "does not have reasonable assurance that the gases that are
used to calibrate emissions monitors for the Acid Rain Program and continuous ambient monitors for the nation's air
monitoring network are accurate". OIG recommended that the Office of Air and Radiation (OAR) implement oversight

1	EPA-600/R-12/531

2	Decker, C.E. et al., 1981. "Analysis of Commercial Cylinder Gases of Nitric Oxide, Sulfur Dioxide, and Carbon Monoxide
at Source Concentrations," Proceedings of the APCA Specialty Conference on Continuous Emission Monitoring-Design,
Operation, and Experience. APCA Publication No. SP-43.

3	"Continuous Emission Monitoring," Code of Federal Regulations, Title 40, Part 75

4	https://www.epa.gov/office-inspector-general/report-epa-needs-oversight-program-protocol-gases-09-P-0235.pdf

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programs to assure the quality of the EPA Protocol Gases that are used to calibrate these monitors. It also
recommended that EPA's Office of Research and Development (ORD) update and maintain the document Traceability
Protocol for Assay and Certification of Gaseous Calibration Standards to ensure that the monitoring programs'
objectives are met.

To address the OIG findings for ambient air monitoring, the Office of Air Quality Planning and Standards (OAQPS), in
cooperation with two EPA Regional Offices, developed an Ambient Air Protocol Gas Verification Program (AA-PGVP).
The program established two gas metrology laboratories to verify the certified concentrations of EPA Protocol Gases
used to calibrate ambient air quality monitors. The program is designed to ensure that producers selling EPA Protocol
Gases are evaluated by the AA-PGVP and provides end users with information about participating producers and
verification results.

The EPA Ambient Air Monitoring Program's QA requirements, Section 2.6.1 of 40 CFR Part 58, Appendix A, are:

2.6.1 Gaseous pollutant concentration standards (permeation devices or cylinders of compressed
gas) used to obtain test concentrations for CO, S02, NO, and N02 must be EPA Protocol Gases
certified in accordance with one of the procedures given in Reference 4 of this appendix.

2.6.1.1	The concentrations of EPA Protocol Gas standards used for ambient air monitoring
must be certified with a 95-percent confidence interval to have an analytical uncertainty of
no more than ±2.0 percent (inclusive) of the certified concentration (tag value) of the gas
mixture. The uncertainty must be calculated in accordance with the statistical procedures
defined in Reference 4 of this appendix.

2.6.1.2	Specialty gas producers advertising certification with the procedures provided in
Reference 4 of this appendix and distributing gases as "EPA Protocol Gas" for ambient air
monitoring purposes must adhere to the regulatory requirements specified in 40 CFR
75.21(g) or not use "EPA" in any form of advertising. Monitoring organizations must provide
information to the EPA on the specialty gas producers they use on an annual basis. POAOs,
when requested by the EPA, must participate in the EPA Ambient Air Protocol Gas
Verification Program at least once every 5 years by sending a new unused standard to a
designated verification laboratory.

This program is considered a verification program because its current level of evaluation does not allow for a large
enough sample of EPA Protocol Gases from any one specialty gas producer to yield a statistically rigorous assessment
of the accuracy of the producer's gases. As indicated in 40 CFR Part 75 Appendix A, EPA Protocol Gases must have a
certified uncertainty (95 percent confidence interval) that must not be greater than plus or minus 2 percent (±2.0%) of
the certified concentration (tag value) of the gas mixture to be used in the Acid Rain Program. The AA-PGVP adopted
this criterion as its data quality objective and developed a quality system to allow the RAVLs to determine whether an
individual protocol gas standard concentration was within ±2% of the certified value.

Purpose of this Document

The purpose of this document is to report the activities that occurred in 2023 and provide the results of the
verifications performed.

Because the AA-PGVP does not sample enough cylinder standards annually to provide a statistically rigorous
assessment of any specialty gas producer, the RAVLs report all valid results as analyzed without declaring a pass or fail

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determination for individual specialty gas producers. However, it is suggested that any assay verification results with
a difference more than ±4% is cause for concern. The AA-PGVP assay verifications are not intended to provide end
users with a scientifically defensible estimate of whether gases of acceptable quality can be purchased from a specific
producer. Rather, the results provide information to end users that the specialty gas producer is evaluated by the
program and provide information that may be helpful when selecting a producer.

This document will not explain the implementation of the AA-PGVP, the quality system or the verification procedures.
That information has been documented in the Implementation Plan, Quality Assurance Project Plan (QAPP) and
standard operating procedures (SOPs). These documents can be found on the AA-PGVP section on the Ambient
Monitoring Technology Information Center (AMTIC)5 website. The AA-PGVP SOPs are in the AA-PGVP QAPP as an
appendix.

2.0 Implementation Summary

Since the program implementation in 2010, when most of the initial preparation work took place, no major new
implementation activities have taken place. However, EPA regional realignments and aging infrastructure reduced the
capabilities of this program. Due to these constraints, the EPA Region 2 Regional Analytical Verification Laboratory
(RAVL) ceased its active participation in the AA-PGVP in calendar year (CY) 2019. In 2020 EPA began reengineering the
AA-PGVP and transitioning Region 2 operations to the Region 4 laboratory. During 2023 the Region 4 RAVL began
performing capability demonstrations and swapping internal quality control samples with the Region 7 RAVL. New
AQS cylinder tracking features have been deployed as optional use for the SLT monitoring programs and some
agencies have started to use these new AQS features.

The following provides a brief overview of the ambient air protocol gas verification program.

Producer Information Data Collection - Beginning in 2010, EPA sent out an Excel spreadsheet to each
monitoring organization to obtain information on the gas standard producers being used by the monitoring
organization and to determine their interest in participating in the program. In 2011, EPA began work with Research
Triangle Institute to develop a web-based survey that one point of contact for each monitoring organization could
access. The intent was to make recording and evaluation of the survey information easier for the monitoring
organizations and EPA. This contracted survey work has since migrated to Battelle. Based on the information
obtained from monitoring organization surveys, EPA would develop a list of the specialty gas producers being used by
the monitoring organizations. From this list, EPA would attempt to perform representative sampling of the standards
from protocol gas production facilities by identifying regulatory monitoring agencies that use standards from each of
these producers. However, for calendar year 2023 only 54 agencies participated in the survey. With only limited
survey results, a systematic selection of producers could not be performed. During calendar year 2023 the AA-PGVP
performed assays on all cylinders submitted by regulatory monitoring agencies. OAQPS continues to develop an Air
Quality System (AQS) database solution to upgrade and replace the specialty gas usage information that is currently
acquired through the contractor based annual questionnaire. During CY-2022 a cylinder metadata entry form to
support the AA-PGVP was created in AQS. Cylinder usage data that was historically collected via the annual survey
began to be collected via AQS. In CY-2022 only 2 agencies (North Dakota DEQ and California Air Resources Board)
used AQS to report the specialty gas producers used for their calibration standards while the other agencies used
EPA's deprecating annual survey system. In CY-2023 the number of agencies using the AQS Maintain Cylinder Form to

5 www.epa.gov/amtic/ambient-air-protocol-gas-verification-program

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report the specialty gas producers used in their monitoring networks increased from these 2 agencies to 24 agencies.
The total number of agencies meeting their protocol gas reporting requirement in calendar year 2023 was 54. Of the
24 agencies using the AQS Maintain Cylinder form, 14 of these agencies elected to solely use this AQS reporting
system and have migrated away from using the annual survey system hosted by EPA's contractor on the AirQA
website.

AA-PGVP Verification Dates - OAQPS worked with the Region 7 Regional Analytical Verification Laboratory
(RAVL) to establish verification dates as indicated in Table 1.

Quarter

Cylinder Receipt

Analysis

1

No later than Mar 10

Mar 20-Mar 31

2

No later than May 26

Jun 5 -Junl6

3

No later than Sept 1

Sept 11-Sept 22

4

No later than Nov 24

Dec 4- Dec 15

Open
House

December 13, 2023

NA

Table 1. RAVL Verification Dates

During Open House the RAVL allows specialty gas producers to visit and ask questions regarding the laboratory
processes and operations. During 2023 no specialty gas producers visited the Region 7 RAVL.

Workflow of the AA-PGVP

Figure 1 provides a flow diagram of the implementation activities of the AA-PGVP. The major activities in these steps
are explained below. More details of these steps are found in the AA-PGVP Implementation Plan, QAPP and SOPs.

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©

Figure 1. AA-PGVP Flow Chart

0.	Specialty Gas Producers procure standards from NIST, or an NMI with a DoE with NIST, to establish traceability of their EPA Protocol Gas
Standards to the SI. RAVLs also procure NIST standards as part of the AA-PGVP.

1.	Monitoring organizations order EPA Protocol Gas Standards as a normal course of business.

2.	EPA sends reminder e-mails to the monitoring organization's points of contact to enter cylinder metadata in AQS or complete AA-PGVP's
Survey. Based on an annual assessment of this information, monitoring organizations are selected to send cylinder standards to EPA for assay
verification. Through consultation with the participating monitoring organization, EPA schedules the assay verifications.

3.	The participating monitoring organizations send a new/unused standard, certificate of analysis, and chain of custody form to the RAVLs for the
assay verification. Standards are returned to the monitoring organization along with the verification results for their standards.

4.	The RAVLs provide the validated results to OAQPS.

5.	When the assay verification results are greater than ±4% of the certified concentration, or greater than ±2% when the expanded measurement
uncertainty is included, specialty gas producers are notified by OAQPS.

6.	OAQPS compiles the year's verification results into an annual report and posts it to the AMTIC website.

3.0 Survey and Verification Results

Monitoring Organization Survey

Based upon the maximum capability of 40 gas cylinders per RAVL per year, the AA-PGVP selection goal, in the

following order, is:

1)	At least one gas standard from every specialty gas producer being used by the monitoring community.

2)	If all specialty gas producers have been assessed at least once, then attempt to verify three standards per
specialty gas producer.

3)	If all specialty gas producers have been assessed three times, weigh additional verifications by producer
market share in the ambient air monitoring community.

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To assess which specialty gas producers are used in the national monitoring network, monitoring organizations can
either complete a web-based survey annually or document the cylinders used at their sites in AQS. Since 2016, EPA
regulations (40 CFR Part 58 Appendix A §2.6.1) require monitoring organizations to annually provide this information.
However, as can be seen from Figure 2, participation in the annual survey has not improved since the 2016 monitoring
rule revisions. The difference in the total surveyed and the AirQA Survey trendlines for CY-2023 (14 agencies) are the
agencies that met this regulatory reporting requirement using AQS alone. EPA intends to phase out the AirQA survey
system in favor of the AQS reporting mechanism. EPA anticipates that this transition to the AQS reporting system will
be completed by July 1, 2025.

AA-PGVP Annual Survey
Participation Trend

300
250
200
150
100
50
0

¦ 1

83

87

58

62

13



J-

51

r

67

2011 2012 2013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023

Year

AQS Agencies ^^^Agencies (S02, CO, N02)
Figure 2. AA-PGVP Annual Survey

¦AirQA Survey

¦Total Surveyed

Verification Results

The AA-PGVP received seven cylinders from SLT monitoring programs for assay verification during calendar year 2023.
These seven cylinders received by the EPA are listed in Table 2. As can be seen from Table 2, some cylinders contain
more than a single calibration gas standard. A summary of the assay results for these cylinders are provided in Tables
4 and 5.

Qtr

Cylinder ID

Pollutant

Lab

Producer

Facility

Agency

2

EB0086492

NO,NOx

7

Airgas

Chicago IL

Missouri Laboratory Services
Program

3

LL40350

CO

7

Airgas

Tooele UT

Colorado Department of Public
Health & Environment

3

CC697663

NO,NOx

7

Airgas

Tooele UT

Utah Department of
Environmental Quality

3

CC697669

NO,NOx

7

Airgas

Tooele UT

Utah Department of
Environmental Quality

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3

FF776

CO

7

Coastal Specialty Gas

Beaumont TX

Oregon Department of
Environmental Quality

3

FF13090

NO, NOx 0

7

Coastal Specialty Gas

Beaumont TX

Oregon Department of
Environmental Quality

4

EX0012199

NO,NOx0

7

Linde

Toledo OH

Wisconsin Dept Of Natural
Resources, Air Monitoring
Section

Table 2. Gas Standards Sent to RAVLs in Calendar Year 2023

Table 2. Gas Standards Sent to RAVLs

Notes: £2 NOx concentration provided by Producer as "informational only" without defining Uncertainty.

Concentration not certified by Producer.

All standards verified in calendar year 2023 were observed to be less than the AA-PGVP action level for concern (±4%).
Figure 3 provides a historical trend showing the improvement in the quality of EPA Protocol Gas Standards from the
inception of the program to present.

Figure 3. Trend of Assay Verification Results performed by EPA ORD and OAQPS

Figure 3. Verification Trend

Information related to the analytical reference standards, analytical instruments and methods used, the data
reduction procedures, and the data assessment procedures are found in the AA-PGVP QAPP and SOP. The AA-PGVP
QAPP is located on EPA's AMTIC website. The SOP can be found as an appendix in the QAPP. Table 3 provides the
measurement quality objectives (MQOs) that are included in the AA-PGVP QAPP (Table 7-1 of the QAPP). The
acceptance criteria in Table 3 were met for each day of verification. In addition, conformance to these requirements
can be found in the measurement data worksheets that are generated for each comparison run and are available
upon request. Appendix A provides a report of the quality control (QC) checks associated with each verification run.
Table 4 is dedicated for the verification results for CO and S02. No S02 standards were submitted by SLTs for
assessment in CY-2023 so only CO results are listed in Table 4. Table 5 provides the NO and NOx verification results.
Tables 4 and 5 are grouped by pollutant standard and then sorted by absolute bias of the assay result.

Two cylinders were received directly from specialty gas producers during 2023. The results are not provided in
summary Tables 4 and 5 because the verifications of the cylinders were not performed blind to the producers but are

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discussed here. Westair provided a direct cylinder submission for an NO standard that was certified at 90.2 ppm.
EPA's verification result for this cylinder was 88.98 ppm (bias of 1.37%). Linde provided a direct cylinder submission
for an S02 standard that was certified at 40.3 ppm. EPA's verification result for this cylinder was 40.00 ppm (bias of
0.76%).

Table 3. MQOs for the AA-PGVP

Requirement

Frequency

Acceptance Criteria

Protocol Gas
Doc. Reference

Comments

Completeness

All standards analyzed

95%

NA

Based on an anticipated 40
cylinders per lab per year.

Quarterly Flow
Calibration

Quarterly -no more than
1 mo. before verification

Calibration flow
accuracy within + 1%

2.3.7

Using flow primary
standard

Calibrator Dilution
Check

Quarterly -within 2 weeks
of assay

+ 1% RD

2.3.5.1

Second SRM. Three or
more discrete
measurements

Analyzer
Calibration

Quarterly - within 2 weeks
of assay

+ 1% RPD (each point)
Slope 0.89-1.02

2.1.7.2

5 points between 50-90%
of upper range limit of
analyzer + zero point

Zero & Span
Verifications

Each day of verification

SE mean < 1% and
accuracy + 5% RD

2.1.7.3, 2.3.5.4

Drift accountability. 3
discrete measurements of
zero and span

Precision Test1

Day of Verification

+ 1% RD standard
error of the mean

2.3.5.4

SRM at conc. >80% of
analyzer URL

Routine Data
Check

Any Standard with Value
>2% Tag Value

NA

NA

Sample run three times to
verify value.

Lab Comparability

2/year

+ 2 % RPD

NA

Sample run three average
value used.

Primary flow
standard

Annually certified by
NVLAP accredited lab

0.4 %

NA

Compared to NIST
Traceable

NISTSRMs

Day of Verification

SRM within
certification period
and Cylinder pressure
> 150 psig

NA

Will follow NIST

recertification

requirements

Table 3. MQOs for the AA-PGVP

1 The precision test does not need to be accomplished if analyzer calibrated on same day as analysis.

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Table 4. 2023 AA-PGVP CO and S02 Verifications*

Producer

Facility

Cylinder ID

Pollutant

Assay Cone

Producer
Cone

%
Bias*

95%
Uncertainty**

Coastal Specialty
Gas

Beaumont TX

FF776

CO

102.7

102

-0.7

0.6

Airgas USA

Tooele UT

LL40350

CO

298.2

298.4

0.1

0.18

Table 4. AA-PGVP CO and S02 Verifications

Notes: * Table grouped by Pollutant and sorted by absolute Bias

** Analyzer uncertainty, see Quality Assurance Requirements Section 13.7 of SOP.

(Analyzer uncertainty value is not the expanded measurement uncertainty)
t An Estimate for the national usage for specific protocol gas producers cannot be determined due to lack of participation in annual
survey and no S02 verifications were performed during CY-2023

Table 5. 2023 AA-PGVP NO and NOx Verifications*

Producer

Facility

Cylinder ID

Pollutant

Assay Cone

Producer
Cone

%

Bias*

95%

Uncertainty**

Coastal Specialty
Gas

Beaumont TX

FF13090

NO

26.2

26.84

2.4

0.16

Airgas USA

Tooele UT

( ( <.T(,(^

\<)

^ :_

55.94

i:

0.16

Lindc Gas and
Equipment Inc.

Toledo OH

EX0012199

NO

30.16

30.3

0.5

0.13

Airgas USA

Tooele UT

( ( (,<>"(,(,<>

\<)

^ U

55.5

o ;

0.16

Airgas USA

Chicago IL

EB0086492

NO

31.95

3 1.96

0

0.35

Coastal Specialty
Gas

Beaumont TX

FF13090

NOX

26.19

26.95

2.9

0.22

Airgas USA

Tooele UT

( ( (,<>"(,(,<>

\<)\

55.96

^ S|

-o X

0.21

Airgas USA

Tooele UT

CC697663

\<)\

55.68

^(. 14

() S

0.22

Linde Gas and
Equipment Inc.

Toledo OH

EX0012199

NOX

30.32

30.5

0.6

0.29

Airgas USA

Chicago IL

EB0086492

NOX

32.16

32.04

-0.4

0.25

Table 5. AA-PGVP NO and NOx Verifications

Notes: * Table grouped by Pollutant and sorted by absolute Bias

** Analyzer uncertainty, see Quality Assurance Requirements Section 13.7 of SOP.

(Analyzer uncertainty value is not the expanded measurement uncertainty)
t An Estimate for the national usage for specific protocol gas producers cannot be determined

due to lack of participation in annual survey
CI NOx concentration provided by Producer as "informational only"; concentration not certified by Producer.

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4.0 Summary and Conclusions

General -

The AA-PGVP is successfully implementing a verification process that is blind to the specialty gas producers. One of the
goals for the AA-PGVP as defined in the ambient air monitoring rule (published March 28, 2016) is for the verifications
performed by the RAVLs to be focused on the standards in use by ambient air monitoring organizations rather than as
a resource to be utilized by specialty gas producers for their own quality assurance. The purpose of the program
(verifications of gas cylinders that are blind to the producers) cannot be accomplished if EPA relies on the specialty gas
producers to submit cylinders for the assessment. All verification results presented in Tables 2, 4, and 5 of this annual
report were submitted by SLT ambient air monitoring programs making the results blind to the specialty gas producers.

While the program is successfully implementing a blind verification process, only seven cylinders, or 9% of the AA-
PGVP goal of 80 cylinders annually, were analyzed in 2023. These seven cylinder submissions resulted in 12
verifications (some cylinders are a blend of multiple gas standards). None of the assay verification results were greater
than the AA-PGVP action level for concern (±4%). While the results of the assay verifications demonstrate high quality
standards being produced by the specialty gas producers, it is difficult to assess whether these results are
representative of the overall quality of the standards used in the national ambient air monitoring networks during
2023. This is due to the low utilization of the RAVL by the SLT monitoring programs and low participation rate in the
annual protocol gas questionnaire. In 2023 there were 26 commercially operated EPA protocol gas production
facilities. It is uncertain how many of these facilities were used in the ambient air monitoring networks in 2023. Of the
26 protocol gas production facilities operating, only four were verified by EPA's ambient air protocol gas verification
program.

Survey Participation -

Since its inception, the AA-PGVP has relied on an annual survey to determine which gas production facilities are used
by the SLTs for generating CO, S02, and N02 calibration test atmospheres. Participation in the annual survey was
initially voluntary. To improve the participation rate and to more completely document which protocol gas producers
are utilized by our ambient air monitoring organizations, in 2016 ambient air monitoring regulations were revised to
require programs using protocol gases to annually complete the survey. While it was thought at the time that this
regulatory requirement would increase the participation rate and create a comprehensive list of the protocol gas
producers used in the national network, the survey participation rate did not improve. In calendar year 2023 SLT
participation in the annual survey could be achieved through the AirQA website or by using AQS cylinder tracking
features that were first deployed in calendar year 2022. These cylinder tracking features in AQS were deployed as
optional use for the SLT monitoring programs in calendar year 2023. EPA plans to make the usage of these AQS
cylinder tracking features required in the future.

SLT participation in reporting their EPA Protocol Gas standards increased from 29% in CY-2022 to 38% in CY-2023. In
calendar year 2023, 10 of the 54 agencies participated by using both the AirQA website and AQS and 14 SLT agencies
participated by solely using these newly developed AQS cylinder reporting features.

RAVLs -

Since the 2016 revisions of the monitoring rule, the AA-PGVP continues to achieve blind verifications of the protocol
gas cylinders used in the ambient air monitoring networks. However, the program still does not achieve its goal of
having every Primary Quality Assurance Organization (PQAO) submit an unused cylinder at least once every five years
for verification. The AA-PGVP's goal to perform 80 protocol gas verifications each year and to strategically select these
protocol cylinders to representatively assess the quality of the standards used in the national ambient air monitoring
networks was not achieved in calendar year 2023. Only seven protocol gas cylinder standards were submitted by

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EPA-454/R-24-007
December 2024

three PQAOs in 2023 to support this national program. The Region 7 RAVL assayed all the cylinders received by SLTs
during this calendar year. A better national sampling of monitoring programs and protocol gas producers continues to
be needed.

The limited verifications performed in 2023 was partially due to the lack of low concentration SRMs currently available
from NIST. This has led to cases where the EPA was forced to decline low concentration cylinder standards offered by
SLT ambient air monitoring programs for assay verification. OAQPS is working to add assay capacity in the future by
using the EPA Region 4 laboratory as an additional RAVL. OAQPS is also working collaboratively with NIST to develop
solutions to the shortage of NIST SRMs available for purchase. In 2023, the EPA began of obtaining primary reference
materials (PRM) from the Netherland's National Metrology Institute (MNI); Dutch Von Swinden Laboratorium (VSL).
NIST has a Declaration of Equivalence (DoE) with VSL and the AA-PGVP will use PRMs from VSL while the NIST SRM
inventory is being replenished.

Quality System -

The AA-PGVP Quality Assurance Project Plan (QAPP) and Standard Operating Procedure (SOP) were written in calendar
year 2010. Changes to the program have occurred since 2010, including regulatory changes in 2016. During calendar
year 2023 EPA was revising these quality system documents to better reconcile them with current operational
practices and regulatory requirements. EPA Region 4 revised the SOP "Standard Operating Procedures for the
Verification of CO Concentrations in EPA Protocol Gas Mixtures" in May 2023. OAQPS contracted Battelle to assist EPA
in revising the AA-PGVP QAPP beginning calendar year 2024. EPA anticipates that revising the QAPP and remaining
SOPs will be a multiyear process.

In 2023, the AA-PGVP operated with a single RAVL. As such, the quality assurance pertaining to the laboratory
intercomparison could not be performed as design in the QAPP. OAQPS is working with EPA Region 4 to use their
laboratory as a second RAVL which, in addition to increasing assay verification capacity, will allow for laboratory
intercomparisons. EPA Region 4 performed multiple test assay verifications throughout calendar year 2023 to
demonstrate competency and proficiency with the EPA ORD Traceability Protocol for Assay and Certification of
Gaseous Calibration Standards. One of the cylinders assayed by the Region 4 RAVL had previously been certified by
EPA Region 7. The agreement between the two labs was very good with only an 0.08% difference between the Region
7 certified CO standard (tag concentration of 4953 ppm) and Region 4 assay result (verified result of 4956.8 ppm).

Once fully operational, the Region 4 RAVL will allow for both increased assay capacity for the AA-PGVP and provide
additional internal quality control between the two RAVLs.

Data Management-

The AA-PGVP has historically relied solely on the annual survey for determining which protocol gas standard producers
are used in the national ambient air monitoring networks. The annual survey was originally voluntary and later in 2016
participation in the survey became a regulatory requirement. Neither implementation of this survey has proven to be
fully effective. The data management practices for conducting the annual survey and storing its results were not
optimized to be readily reconciled with the data produced by the RAVLs.

In response OAQPS developed an AQS database solution in 2022 to replace the data management practices historically
performed by EPA's contractor. This includes an AQS form for SLT monitoring programs to submit their cylinder
metadata; and modifications to the AQS "QA-Transaction" file format used for uploading 1-Point Quality Control check
and Annual Performance Evaluation audit results. These AQS modifications allow for documenting the protocol gas
standard used for generating the test atmosphere for the QA/QC check. Utilizing this modified AQS data submission
process will allow EPA to document 100% of the protocol gas production facilities used in the ambient air monitoring
networks compared to the historic process that has on average only been 29% effective since 2011. Two monitoring

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December 2024

programs used the AQS Cylinder maintain form in calendar year 2022. During calendar year 2023, 24 monitoring
programs utilized the AQS maintain cylinder form. Of these 24 SLT monitoring programs, eight of these agencies
began also including cylinder metadata with their QA/QC submissions to AQS. EPA's goal during CY-2024 is to see
increased adoption of these AQS cylinder tracking features and to fully replace the historic annual survey system with
these AQS cylinder tracking features in the future.

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Appendix A

QA Reports from Measurement Data Worksheets for 2023

Ambient Air Protocol Gas Verification Program
QA Reports from Measurement Data Worksheets for 2023

During the verification process, the Regional Analytical Verification Laboratories perform quality control checks that
are recorded on the Measurement Data Worksheets used to document these verifications. This information is
reported and saved along with the verification reports. The following sheets represent the quality control for the
verifications that were implemented in 2023.

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December 2024

QA Requirements Summary

QA Requirement	Result	Status



Primary SRM Cylinder Expiration Date

14-Sep-25

Primary SRM Gas Standard OK

SRM Gas Standards

Primary SRM Cylinder Pressure >150 psi

1450

Primary SRM cylinder pressure is OK

SRM Dilution Check Cylinder Expiration Date

1-Feb-24

Dilution Check SRM Gas Standard OK



Dilution Check SRM Cylinder Pressure >150 psi

200

Dilution check SRM cylinder pressure is OK



High Flow Standard Expiration Date

5-Dec-23

Standard OK

Laboratory Flow Standard

Low Flow Standard Expiration Date

6-Dec-23

Standard OK



Ultra Low Flow Expiration Date

9-Feb-24

Standard OK



Calibrator Flow Calibration within 2 weeks of assay

5-Jun-23

Calibrator flow calibration within 2 weeks of assay

Calibrator (mass flow controllers)

Calibrated High Flow MFC Slope Range = 0.99 -1.01

0.9999986

High MFC OK



Calibrated Low Flow MFC Slope Range = 0.99 - 1.01

0.9999990

Low MFC OK



Analyzer Calibration within 2 weeks of assay

6-Jun-23

Analyzer calibration within 2 weeks of assay

Estimate of Uncetainty < 1% at point #1 (>80% URL)

0.39%

Assay may be conducted at this concentration

Oxides of Nitrogen Gas Analyzer
NO Portion

Estimate of Uncetainty < 1% at point #2

0.39%

Assay may be conducted at this concentration

Estimate of Uncetainty < 1% at point #3

0.41%

Assay may be conducted at this concentration

Estimate of Uncetainty < 1% at point #4

0.42%

Assay may be conducted at this concentration



Estimate of Uncetainty < 1% at point #5 (~50% URL)

0.44%

Assay may be conducted at this concentration



Analyzer slope is within 0.98-1.02

0.9982

Analyzer Slope is acceptable



Analyzer Calibration within 2 week of assay

6-Jun-23

Analyzer calibration within 2 weeks of assay

Estimate of Uncetainty < 1% at point #1 (>80% URL)

0.30%

Assay may be conducted at this concentration

Oxides of Nitrogen Gas Analyzer
NOx Portion

Estimate of Uncetainty < 1% at point #2

0.31%

Assay may be conducted at this concentration

Estimate of Uncetainty < 1% at point #3

0.32%

Assay may be conducted at this concentration

Estimate of Uncetainty < 1% at point #4

0.33%

Assay may be conducted at this concentration



Estimate of Uncetainty < 1% at point #5 (~50% URL)

0.35%

Assay may be conducted at this concentration



Analyzer slope is within 0.98-1.02

0.9997

Analyzer Slope is acceptable

Dilution Check

Dilution Check Date within 2 weeks of assay

6-Jun-23

Dilution check within 2 weeks of assay

Dilution Check Relative % Difference < 1%

0.641%

Dilution Check RSD is OK



Day of Assay Zero Check - Std. Error < 1 %

Std. Error is okay.

Zero Gas Std. Error is OK

Day of Assay Zero/Span Check
NO Portion

Day of Assay Zero Check - Relative Difference < 5%

RD is okay.

Zero Gas RD is OK

Day of Assay Span Check - Std. Error < 1 %

Std. Error is okay.

Span Gas Std. Error is OK



Day of Assay Span Check - Relative Difference <5%

RD is okay.

Span Gas RD is OK



Day of Assay Zero Check - Std. Error < 1 %

Std. Error is okay.

Zero Gas Std. Error is OK

Day of Assay Zero/Span Check
NOx Portion

Day of Assay Zero Check - Relative Difference < 5%

RD is okay.

Zero Gas RD is OK

Day of Assay Span Check - Std. Error < 1 %

Std. Error is okay.

Span Gas Std. Error is OK



Day of Assay Span Check - Relative Difference <5%

RD is okay.

Span Gas RD is OK



,, - Challenge Standard#1 Std. Error < 1%
Challenge Standard #1 NO Assay M

Challenge Standard #1 vendor certificate bias

The standard error is okay.

Challenge Standard #1 Std. Error is OK

0.02%

Challenge Std. #1 vendor certificate bias < 2%



,, - Challenge Standard#1 Std. Error < 1%
Challenge Standard #1 NOx Assay M

Challenge Standard #1 vendor certificate bias

The standard error is okay.

Challenge Standard #1 Std. Error is OK

-0.36%

Challenge Std. #1 vendor certificate bias < 2%

Figure 4. QA Summary for Test NO of EB0086492 (Std #1)

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December 2024

QA Requirements Summary

QA Requirement	Result	Status



Primary SRM Cylinder Expiration Date

30-Sep-27

Primary SRM Gas Standard OK

SRM Gas Standards

Primary SRM Cylinder Pressure >150 psi

1625

Primary SRM cylinder pressure is OK

SRM Dilution Check Cylinder Expiration Date

15-Mar-31

Dilution Check SRM Gas Standard OK



Dilution Check SRM Cylinder Pressure >150 psi

1800

Dilution check SRM cylinder pressure is OK



High Flow Standard Expiration Date

18-May-24

Standard OK

Laboratory Flow Standard

Low Flow Standard Expiration Date

13-Jun-24

Standard OK



Base

27-Jun-24

Standard OK





Calibrator Flow Calibration within 2 weeks of assay

9-Sep-23

Calibrator flow calibration within 2 v\eeks of assay

Calibrator (mass flow controllers)

Calibrated High Flow MFC Slope Range = 0.99 -1.01

0.9999992

High MFC OK



Calibrated Low Flow MFC Slope Range = 0.99-1.01

0.9999798

Low MFC OK



Analyzer Calibration within 2 \Aeek of assay

12-Sep-23

Analyzer calibration within 2 \Aeeks of assay



Estimate of Uncetainty < 1% at point#1 (>80% URL)

0.25%

Assay may be conducted at this concentration



Estimate of Uncetainty < 1 % at point#2

0.25%

Assay may be conducted at this concentration

Carbon Monoxide Gas Analyzer

Estimate of Uncetainty < 1% at point#3

0.26%

Assay may be conducted at this concentration



Estimate of Uncetainty < 1 % at point#4

0.28%

Assay may be conducted at this concentration



Estimate of Uncetainty < 1% at point#5 (~50% URL)

0.31%

Assay may be conducted at this concentration



Analyzer slope is within 0.98-1.02

1.0018

Analyzer Slope is acceptable

Dilution Check

Dilution Check Date within 2 \Aeeks of assay

12-Sep-23

Dilution check wthin 2 \Aeeks of assay

Dilution Check Relative % Difference <1%

0.353%

Dilution Check RSD is OK







Day of Assay Zero/Span Check

Day of Assay Zero Check - Std. Error < 1 %

Day of Assay Zero Check - Relative Difference < 5%

Std. Error is okay.
RD is okay.

Zero Gas Std. Error is OK
Zero Gas RD is OK

Day of Assay Span Check - Std. Error < 1 %

Std. Error is okay.

Span Gas Std. Error is OK



Day of Assay Span Check - Relative Difference <5%

RD is okay.

Span Gas RD is OK





,, ¦ ¦ j±m a Challenge Standard #1 Std. Error < 1 %
Challenge Standard #1 Assay a

Challenge Standard #1 vendor certificate bias

The standard error is okay.

-0.08%

Challenge Standard #1 Std. Error is OK
Challenge Std. #1 vendor certificate bias < 2%

Figure 5. QA SUMMARY FOR CO TEST OF LL40350 (STD #1)

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December 2024

QA Requirements Summary

QA Requirement	Result	Status



Primary SRM Cylinder Expiration Date

15-Mar-31

Primary SRM Gas Standard OK

SRM Gas Standards

Primary SRM Cylinder Pressure >150 psi

1750

Primary SRM cylinder pressure is OK

SRM Dilution Check Cylinder Expiration Date

2-Jul-28

Dilution Check SRM Gas Standard OK



Dilution Check SRM Cylinder Pressure >150 psi

1625

Dilution check SRM cylinder pressure is OK





High Flow Standard Expiration Date

18-May-24

Standard OK

Laboratory Flow Standard

Low Flow Standard Expiration Date

13-Jun-24

Standard OK



Base

27-Jun-24

Standard OK





Calibrator Flow Calibration within 2 weeks of assay

9-Sep-23

Calibrator flow calibration within 2 v\eeks of assay

Calibrator (mass flow controllers)

Calibrated High Flow MFC Slope Range = 0.99 -1.01

0.9999992

High MFC OK



Calibrated Low Flow MFC Slope Range = 0.99 -1.01

0.9999798

Low MFC OK



Analyzer Calibration within 2 \Aeek of assay

18-Sep-23

Analyzer calibration within 2 \Aeeks of assay



Estimate of Uncetainty < 1% at point#1 (>80% URL)

0.71%

Assay may be conducted at this concentration



Estimate of Uncetainty < 1 % at point#2

0.73%

Assay may be conducted at this concentration

Carbon Monoxide Gas Analyzer

Estimate of Uncetainty < 1% at point#3

0.77%

Assay may be conducted at this concentration



Estimate of Uncetainty < 1 % at point#4

0.82%

Assay may be conducted at this concentration



Estimate of Uncetainty < 1% at point#5 (~50% URL)

0.88%

Assay may be conducted at this concentration



Analyzer slope is within 0.98-1.02

1.0021

Analyzer Slope is acceptable

Dilution Check

Dilution Check Date within 2 \Aeeks of assay

18-Sep-23

Dilution check wthin 2 \Aeeks of assay

Dilution Check Relative % Difference <1%

-0.371%

Dilution Check RSD is OK







Day of Assay Zero/Span Check

Day of Assay Zero Check - Std. Error < 1 %

Day of Assay Zero Check - Relative Difference < 5%

Std. Error is okay.
RD is okay.

Zero Gas Std. Error is OK
Zero Gas RD is OK

Day of Assay Span Check - Std. Error < 1 %

Std. Error is okay.

Span Gas Std. Error is OK



Day of Assay Span Check - Relative Difference <5%

RD is okay.

Span Gas RD is OK





,, ¦ ¦ j±m a Challenge Standard #1 Std. Error < 1 %
Challenge Standard #1 Assay a

Challenge Standard #1 vendor certificate bias

The standard error is okay.

0.68%

Challenge Standard #1 Std. Error is OK
Challenge Std. #1 vendor certificate bias < 2%

Figure 6. QA SUMMARY FOR CO TEST OF FF776 (STD #1)

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EPA-454/R-24-007
December 2024

QA Requirements Summary

QA Requirement	Result	Status



Primary SRM Cylinder Expiration Date

14-Sep-25

Primary SRM Gas Standard OK

SRM Gas Standards

Primary SRM Cylinder Pressure >150 psi

1350

Primary SRM cylinder pressure is OK

SRM Dilution Check Cylinder Expiration Date

1-Feb-24

Dilution Check SRM Gas Standard OK



Dilution Check SRM Cylinder Pressure >150 psi

200

Dilution check SRM cylinder pressure is OK



High Flow Standard Expiration Date

5-Dec-23

Standard OK

Laboratory Flow Standard

Low Flow Standard Expiration Date

6-Dec-23

Standard OK



Ultra Low Flow Expiration Date

9-Feb-24

Standard OK



Calibrator Flow Calibration within 2 weeks of assay

9-Sep-23

Calibrator flow calibration within 2 weeks of assay

Calibrator (mass flow controllers)

Calibrated High Flow MFC Slope Range = 0.99 -1.01

0.9999992

High MFC OK



Calibrated Low Flow MFC Slope Range = 0.99 - 1.01

0.9999798

Low MFC OK



Analyzer Calibration within 2 weeks of assay

13-Sep-23

Analyzer calibration within 2 weeks of assay



Estimate of Uncetainty < 19

o at point #1 (>80% URL)

0.21%

Assay may be conducted at this concentration

Oxides of Nitrogen Gas Analyzer
NO Portion

Estimate of Uncetainty < 19

at point #2

0.21%

Assay may be conducted at this concentration

Estimate of Uncetainty < 19

at point #3

0.22%

Assay may be conducted at this concentration

Estimate of Uncetainty < 19

at point #4

0.24%

Assay may be conducted at this concentration



Estimate of Uncetainty < 19

oat point #5 (-50% URL)

0.26%

Assay may be conducted at this concentration



Analyzer slope is within 0.9J

-1.02

1.0020

Analyzer Slope is acceptable



Analyzer Calibration within 2 week of assay

13-Sep-23

Analyzer calibration within 2 weeks of assay



Estimate of Uncetainty < 19

oat point #1 (>80% URL)

0.35%

Assay may be conducted at this concentration

Oxides of Nitrogen Gas Analyzer
NOx Portion

Estimate of Uncetainty < 19

at point #2

0.36%

Assay may be conducted at this concentration

Estimate of Uncetainty < 19

at point #3

0.38%

Assay may be conducted at this concentration

Estimate of Uncetainty < 19

at point #4

0.40%

Assay may be conducted at this concentration



Estimate of Uncetainty < 19

oat point #5 (-50% URL)

0.44%

Assay may be conducted at this concentration



Analyzer slope is within 0.9J

-1.02

1.0001

Analyzer Slope is acceptable

Dilution Check

Dilution Check Date within 2 weeks of assay

12-Sep-23

Dilution check within 2 weeks of assay

Dilution Check Relative % Difference < 1%

0.183%

Dilution Check RSD is OK



Day of Assay Zero Check - Std. Error < 1 %

Std. Error is okay.

Zero Gas Std. Error is OK

Day of Assay Zero/Span Check

Day of Assay Zero Check - Relative Difference < 5%

RD is okay.

Zero Gas RD is OK

NO Portion

Day of Assay Span Check - Std. Error < 1 %

Std. Error is okay.

Span Gas Std. Error is OK



Day of Assay Span Check - Relative Difference <5%

RD is okay.

Span Gas RD is OK



Day of Assay Zero Check - Std. Error < 1 %

Std. Error is okay.

Zero Gas Std. Error is OK

Day of Assay Zero/Span Check

Day of Assay Zero Check - Relative Difference < 5%

RD is okay.

Zero Gas RD is OK

NOx Portion

Day of Assay Span Check - Std. Error < 1 %

Std. Error is okay.

Span Gas Std. Error is OK



Day of Assay Span Check - Relative Difference <5%

RD is okay.

Span Gas RD is OK

Challenge Standard #1 NO Assay

Challenge Standard #1 Std. Error < 1%

The standard error is okay.

Challenge Standard #1 Std. Error is OK

Challenge Standard #1 vendor certificate bias

0.29%

Challenge Std. #1 vendor certificate bias < 2%



Challenge Standard #1 NOx Assay

Challenge Standard #1 Std. Error < 1%

The standard error is okay.

Challenge Standard #1 Std. Error is OK

Challenge Standard#! vendor certificate bias

-0.80%

Challenge Std. #1 vendor certificate bias < 2%

Challenge Standard #2 NO Assay

Challenge Standard #2 Std. Error < 1%

The standard error is okay.

Challenge Standard #2 Std. Error is OK

Challenge Standard #2 vendor certificate bias

1.22%

Challenge Std. #2 vendor certificate bias < 2%



Challenge Standard #2 NOx Assay

Challenge Standard #2 Std. Error < 1%

The standard error is okay.

Challenge Standard #2 Std. Error is OK

Challenge Standard #2 vendor certificate bias

0.82%

Challenge Std. #2 vendor certificate bias < 2%



Challenge Standard #3 NO Assay

Challenge Standard #3 Std. Error < 1%

The standard error is okay.

Challenge Standard #3 Std. Error is OK

Challenge Standard #3 vendor certificate bias

2.46%

Challenge Std. #3 vendor certificate bias between 2-4%



Challenge Standard #3 NOx Assay

Challenge Standard #3 Std. Error < 1%

The standard error is okay.

Challenge Standard #3 Std. Error is OK

Challenge Standard #3 vendor certificate bias

2.91%

Challenge Std. #3 vendor certificate bias between 2-4%

Figure 7. QA SUMMARY FOR NO TEST OF CC697669 (STD #1), CC697663 (STD #2), FF13090 (STD #3)

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December 2024

QA Requirements Summary

QA Requirement	Result	Status



Primary SRM Cylinder Expiration Date

14-Sep-25

Primary SRM Gas Standard OK

SRM Gas Standards

Primary SRM Cylinder Pressure >150 psi

1200

Primary SRM cylinder pressure is OK

SRM Dilution Check Cylinder Expiration Date

1-Feb-24

Dilution Check SRM Gas Standard OK



Dilution Check SRM Cylinder Pressure >150 psi

200

Dilution check SRM cylinder pressure is OK



High Flow Standard Expiration Date

18-May-24

Standard OK

Laboratory Flow Standard

Low Flow Standard Expiration Date

13-Jun-24

Standard OK



Ultra Low Flow Expiration Date

27-Jun-24

Standard OK



Calibrator Flow Calibration within 2 weeks of assay

2-Dec-23

Calibrator flow calibration within 2 weeks of assay

Calibrator (mass flow controllers)

Calibrated High Flow MFC Slope Range = 0.99 -1.01

0.9999957

High MFC OK



Calibrated Low Flow MFC Slope Range = 0.99- 1.01

0.9999920

Low MFC OK



Analyzer Calibration within 2 weeks of assay

4-Dec-23

Analyzer calibration within 2 weeks of assay

Estimate of Uncetainty < 1% at point #1 (>80% URL)

0.08%

Assay may be conducted at this concentration

Oxides of Nitrogen Gas Analyzer
NO Portion

Estimate of Uncetainty < 1% at point #2

0.08%

Assay may be conducted at this concentration

Estimate of Uncetainty < 1% at point #3

0.09%

Assay may be conducted at this concentration

Estimate of Uncetainty < 1% at point #4

0.09%

Assay may be conducted at this concentration



Estimate of Uncetainty < 1% at point#5 (~50% URL)

0.09%

Assay may be conducted at this concentration



Analyzer slope is within 0.98-1.02

0.9997

Analyzer Slope is acceptable



Analyzer Calibration within 2 week of assay

4-Dec-23

Analyzer calibration within 2 weeks of assay

Estimate of Uncetainty < 1% at point #1 (>80% URL)

0.40%

Assay may be conducted at this concentration

Oxides of Nitrogen Gas Analyzer
NOx Portion

Estimate of Uncetainty < 1% at point #2

0.41%

Assay may be conducted at this concentration

Estimate of Uncetainty < 1% at point #3

0.41%

Assay may be conducted at this concentration

Estimate of Uncetainty < 1% at point#4

0.42%

Assay may be conducted at this concentration



Estimate of Uncetainty < 1% at point #5 (~50% URL)

0.44%

Assay may be conducted at this concentration



Analyzer slope is within 0.98-1.02

0.9972

Analyzer Slope is acceptable

Dilution Check

Dilution Check Date within 2 weeks of assay

3-Dec-23

Dilution check within 2 weeks of assay

Dilution Check Relative % Difference < 1%

0.459%

Dilution Check RSD is OK



Day of Assay Zero Check - Std. Error < 1 %

Std. Error is okay.

Zero Gas Std. Error is OK

Day of Assay Zero/Span Check

Day of Assay Zero Check - Relative Difference < 5%

RD is okay.

Zero Gas RD is OK

NO Portion

Day of Assay Span Check - Std. Error < 1 %

Std. Error is okay.

Span Gas Std. Error is OK



Day of Assay Span Check - Relative Difference <5%

RD is okay.

Span Gas RD is OK



Day of Assay Zero Check - Std. Error < 1 %

Std. Error is okay.

Zero Gas Std. Error is OK

Day of Assay Zero/Span Check
NOx Portion

Day of Assay Zero Check - Relative Difference < 5%

RD is okay.

Zero Gas RD is OK

Day of Assay Span Check - Std. Error < 1 %

Std. Error is okay.

Span Gas Std. Error is OK



Day of Assay Span Check - Relative Difference <5%

RD is okay.

Span Gas RD is OK



A Challenge Standard #1 Std. Error < 1%
Challenge Standard #1 NO Assay M

Challenge Standard #1 vendor certificate bias

The standard error is okay.

Challenge Standard #1 Std. Error is OK

0.47%

Challenge Std. #1 vendor certificate bias < 2%



,, - Challenge Standard#1 Std. Error < 1%
Challenge Standard #1 NOx Assay M

Challenge Standard#! vendor certificate bias

The standard error is okay.

Challenge Standard #1 Std. Error is OK

0.58%

Challenge Std. #1 vendor certificate bias < 2%

Figure 8. QA SUMMARY FOR NO TEST OF EX0012199 (STD #1)

Page 24 of 24


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United States	Office of Air Quality Planning and Standards	Publication No. EPA-454/R-24-007

Environmental Protection	Air Quality Assessment Division	December 2024

Agency	Research Triangle Park, NC


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