PB*3-191*2?
EFA/60O/A-93/1O?
Two New Gas Standards Programs
At the National Institute o*
standards arsd Technology
by
William J, Mitchell, Ph.D.
U.S. Environmental Protection Agency
Atmospheric Research and Exposure
Assessment Laboratory
Research Triangle Park, NC 27711
and
Willie E. May, Ph.D.
National Institute of Standards and Technology
Organic Analytical Research Division
Gaithersburg, JfD 20899
frB8TRA?£
The EPA/NIST certified reference materials (CRM) program is being
terminated and replaced with two new ones: the HIST Traceable
Reference Materials (NTRM) and the Research Gas Mixture (RGM}
programs. These new programs are being implemented to provide HIST
traceability to a wider number of gas mixtures. The NTRM program
will differ from the CRM program in two significant ways:
candidate gas mixtures will not have to be identical to a MIST
Standard Reference Material (SRM), and the producer of the NTRM
rather than EPA will pay NIST to check the concentration of the gas
mixture. In the RGM program, NIST will enter into agreements with
either governmental, commercial or private organizations to produce
gas mixtures for which there are no SRMs or which lie outside the
concentration range of existing SRtts. The details of these
programs are presented in this paper.
Key Words - 5RM, Protocol Gas, NIST, CRM
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Many EPA ambient air, stationary source and mobile source
regulations Mandate the use of gaseous concentration standards
traceable to the National Institute of Standards and Technology
(NIST) for calibrating the pollutant measurement systems
Standard Reference Materials, (SRMs), which art certified and sold
by the HIST are the highest quality, NIST-traceable standards
available. Presently, NIST supplies SRMs for the following
pollutant gases regulated by the EPA: MO, NO,, SO,, CO, C0;, O,, and
H,S.
The above SRMs were developed by the NIST in cooperation with
the EPA. In anticipation that the MIST alone could not meet the
deisand for NIST-traceable standards, EPA and NIST implemented two
other mechanisms to meet this demand. These mechanises, the
Protocol Gas program and the Certified Reference Materials (CRM)
program were begun to allow the specialty gas industry to provide
gas standards traceable to MIST SRMs at costs less than those for
SRMs. The Protocol Gas program^' has been quite successful. It is
targeted principally to those who use specialty gas mixtures to
calibrate air pollutant monitoring systems, whereas the SRM and CRM
programs are targeted for use by the specialty gas industry.
Protocol Gases cost 10 to 25% of the corresponding SRM, are
certified as stable for periods close to or equal to those of the
corresponding SRMs and are made to order by the specialty gas
industry.
In contrast, the CRM program'1' has not achieved its intended
purpose, most likely because CRMs are very close in quality and
other characteristics SRMs. As shown in Table 1, for the cost
of a CRM, the potential CRM purchaser can have an SRM, a higher
quality standard with a longer stability period. Also, suppliers
Of specialty gases are reluctant to prepare CRMs because the lead
tine required means they have to prepare each CRM batch on
speculation that they can sell and/or use them quickly after the
CRM batch Is certified. They cannot sake only the nuaber of CRMs
needed to seet their internal needs, e.g. for calibration and QC
standards, because public funds are used to spot-check the
supplier's assay of the CRM batch. Thus, EPA requires suppliers of
CRMs to make a sufficient number of cylinders in each CRM batch to
be able to sell some of them to others, including competitors in
the specialty gas industry.
The CRM program is now being replaced by the NIST Traceable
Reference Materials {NTRM) program, which/'HIST and EPA^'hope will
correct the deficiencies in the CRM prograa. NTRMs will differ
from CRMs in the following ways:
2
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1. The NTRM concentration can be lit or between those of SRMs
for the came analyte and balance gas.
2, NIST rather than EPA, will spot-cheek. the assay of the
NTRM batch.
J. MIST will assign the analyte concent rat ion (•) to the
MTHM.
4. The supplier of the NTRM will pay MI ST for the spot-check
of assay.
5. The NTRM will not have to be sold to others since no
public funds are used in the certification.
Table 2 provides a fuller comparison off the NTRM and CRM
progratas.
But, what if an organization needs a high quality gas standard
where either (1} the analyte is the same as an SRM but where the
concentration is outside the range of the existing SRMs or (2) the
analyte(s) and/or the balance gas are different from an SRM? The
HIST and the EPA are implementing the Research Gas Mixture (RGM)
program to address these situations. Under the RGM prograa, the
HIST will enter into an agreement with another party, such as a
government agency, a trade organization cr a specialty gas company,
to produce gas mixtures that have different analytes, different
balance gases or concentrations outside the range of available
SRMs. Since the requesting organization will fund the work, the
RGM will be the property of the sponsor but any primary standards
developed will be the property of the NIST,
Key features of the RGM program are:
1. Applicable to gas mixtures not covered by the SRM or NTRM
programs.
2. Gas mixture likely can be made.
3. Requestor contacts NIST to discuss procedures and development
costs.
4. Work statement, schedule, milestones, and deliverables are
specified in written agreement with MIST.
5. Requestor funds project up front to amount agreed upon with
NIST.
6. NIST develops new or extends current primary standards
required to perform the analysis of the candidate RGM.
7. NIST analyzes primary standards suite for precision and
accuracy.
a. NIST analyzes candidate RGM to determine analyte
concentration
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WIST and EPA are now preparing documents that will describe in
detail the mechanics of the NTRH and the RGM programs. At this
time, some key features of both programs are not firm. One of
these is the question of "Exclusivity", that is, what rights will
the organization paying for the development of an RGK have to the
exclusive use of the NIST primary standards developed as part of
the work? For example, should they have exclusive use forever, for
24 months, etc. ? If Company B is willing to pay the NIST to
develop similar or identical primary standards to those developed
for Company A, can or should the HIST do this? If many companies
ask the NIST to develop RGMs similar to those developed for Company
h, such that development of an SKH is warranted, can the HIST
develop the 5RM? If EPA decides to regulate a pollutant covered by
an RGM, does the NIST have a responsibility to develop an SRJi even
if it means the owner of the RGM loses market shure?
Two other areas where details are not yet firm are:
1. If the first attempt to develop an RGM fails, but the
information obtained allows NIST to develop that RGM for
someone else, does the first organization have any rights
to the RGM?
2. What should the defined period of stability be for each
RGK and NTRH and how should the stability be monitored?
None of these questions is easy to answer; in the end, they
probably will be decided on a case by case basis.
Disclaimer
The information in this document has been funded wholly by the
united States Environmental Protection Agent y. It has been
subjected to Agency review and approved for publication.
BHSrawcM
1. code of Federal Regulations, Title 40, Parts 50, 58, 60 and
75. Office of the Federal Register, Washington, D.C.
2. "Revised EPA Protocol for Assay and Certification of
Compressed Gas Calibration Standards." Draft, April 1993.
Available from the U.S. EPA, Atmospheric Research and Exposure
Assessment Laboratory, MD-77B, Research Triangle Park, NC
27711.
3. "A Procedure for Establishing Traceability of Gas Mixtures to
Certain National Bureau of Standards SRMs." EPA-600/7-61-010,
Joint Publication of the National Bureau of Standards and the
Environmental Protection Agency. May 1981*
4
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Table Comparison between SRMs and CRM**
Par u« tar
IU
CM
Miniautn Batch Size
20
10
Cost Each
$800 - $1500
$800 - $1500
Gas volume
30 CU. ft.
ISO cu. ft.
Analyte Concentration
MIST's choice
Must be within
±11 of SRMs
Balance Gas
NIST's choice
Must be same as
SUM
Analyte Assayed Using
HIST Primary
Standards
SRMs
Assay Done by
MIST
Supplier of CRM
with EPA spot-
check assay**. .
Uncertainty in Assay
til
Up to ±2t
Assay Valid For
24 - 48 months
12 - 24 nonths
Assay certification
Period Begins
When SttH sold
When CRM Batch
is certified
Time From preparation to
Availability
IS - 36 months
6 - 12 months
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Table 2, Comparison between NTRH and CRM programs
CRM
imsM
Company decides needs
same
Company prepares mixtures
Company contacts NIST; after
agreement, mixtures made
Company performs analyses
Sane
Data sent to EPA
Data sent to NIST
EPA selects two cylinders for
analysis
HIST selects cylinders for
analysis
Cylinders analyzed by EPA
Cylinders analyzed at WIST
All data sent to HIST
Sane
Audit lab concurs with
concentration
NIST assigns concentration
Audit costs covered by EPA
Costs covered by producer
($4500 - $«000)
Company provides assay
certificate
NIST provides assay
certificate
Company distributes mixtures
Same
Company responsible for
stability
Same
6
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TECHNICAL REPORT DATA
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U. J. Mitchell and M. 1. May
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Organic Analytical Research Division
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Research Triable Park, NC 27711
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For presentation at 1993 EPA/AWMA Symposium or» "Measurement of Toxic and leseted
Air Pollutants" Durttan,. NC . May 3-7, 1993
16
The EPA/N1ST certified reference materials (CRM) program is
being terminated arid replaced with two new ones; the HIST
Traceable Reference Materials {NTRM} and the Research Gas Mixture
(RGM) programs. These new programs arc being ioplesiented to
provide NIST traceability to a wider number of gas fixtures. The
ntrk program will differ from the CRM program in two significant
ways; candidate gas mixtures will net have to be identical tc a
HI ST Standard Reference Material (SRK) , and the producer of the
NTRM rather than EPA will pay MIST to check the concentratiop of
the gas mixture. In the RGM progran, NI ST will enter ir.tc
agreements with either governmental, commercial or private
organizations to produce gas mixtures for which there are no 5KKs
or which lie outside the concentration range of existing SRMs. The
details ot these pro-grans are presented in this paper,
17 HC * »P"OS AND DOCyMisT
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