United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
Research Triangle Park, NC 27711
Research and Development
EPA/600/S4-88/016 July 1988
&EPA Project Summary
Stability of Parts-per-Billion
Hazardous Organic Cylinder
Gases and Performance Audit
Results of Source Test and
Ambient Air Measurement
Systems: Status Report #4
R.K.M. Jayanty, C.K. Sokol, C.E. Decker and D.J. von Lehmden
An evaluation of 29 gaseous
organic compounds at parts-per-
billion (ppb) levels In compressed
gas cylinders has been established
under a contract with the United
States Environmental Protection
Agency (USEPA). The primary
objectives of this on-going project
are: (1) to evaluate the quality of
measurements made by USEPA,
state/local agencies, or their con-
tractors by using ppb gas cylinders
for performance audits to assess the
relative accuracy of source mea-
surement systems during hazardous
waste trial burn tests and ambient air
monitoring programs; (2) to verify the
manufacturer's certified analysis of
the multi-component gas mixtures;
(3) to determine the stability of the
gas mixtures with time; and (4) to
develop new audit materials as
requested by USEPA.
The cylinders consist of five
mixtures of five, six, eight, nine, and
eighteen organic compounds each.
These mixtures were blended by a
commercial gas supplier in alum-
inum cylinders in a balance gas of
nitrogen. The five component mixture
(Group I) contains carbon tetra-
chloride, chloroform, tetrachloro-
ethylene (perchloroethylene), vinyl
chloride and benzene. The nine
component mixture (Group II)
includes trichloroethylene, 1,2-
dichloroethane (ethylene dichloride),
1,2-dibromoethane (ethylene dibro-
mide), acetonitrile, trichlorofluoro-
methane (F-11), dlchlorodifluoro-
methane (F-12) bromomethane
(methyl bromide), methyl ethyl
ketone and 1,1,1-trichloroethane.
The eight component mixture (Group
III) includes pyridine*, vinylidene
chloride, 1,1,2-trichloro-1,2,2-tri-
fluoroethane (F-113), 1,2-dichloro-
1,1,2,2-tetrafluoroethane (F-114),
acetone, 1,4-dioxane, toluene, and
chlorobenzene. The six component
mixture (Group IV) includes acrylo-
nitrile, 1,3-butadiene, ethylene oxide,
methylene chloride, propylene oxide
and o-xylene. The eighteen com-
ponent mixture (Group V) includes
vinyl chloride, 1,3-butadiene, bro-
momethane, trichlorofluoromethane,
(F-11), methylene chloride, chloro-
form, 1,2-dichloroethane, 1,1,1-
trichloroethane, benzene, carbon
tetrachloride, 1,2-dichloropropane,
trichloroethylene, toluene, 1,2-di-
bromoethane, tetrachloroethylene,
chlorobenzene, ethylbenzene and o-
xylene. To date, 198 performance
audits have been initiated and 172
"Although Group III cylinders contain pyridine, the
concentrations are not certified due to severe
analytical difficulties
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are complete. The results of these
audits and a description of the
experimental procedures used for
analyses and available stability data
are presented in the status report.
Generally, the results of the audits
show reasonable agreement (± 50
percent) with the audit material
concentrations measured by
Research Triangle Institute (RTI),
considering the low concentrations
of the organics and the anticipated
uncertainty associated with inde-
pendent analyses conducted by an
audit laboratory.
Stability studies for all Group I,
Group II, Group III (except pyridine),
Group IV and Group V compounds
have been performed. Results in-
dicate that all the compounds tested
are adequately stable for use as
reliable audit materials with the ex-
ception of ethylene oxide and pro-
pylene oxide at low concentrations.
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
documented in a separate report of
the same title (see Project Report
ordering information at back).
Introduction
The application of Quality Assurance
practices is important to the generation
of high-quality environmental data. The
Quality Assurance Division of USEPA's
Environmental Monitoring Systems
Laboratory has initiated a program to
supply audit materials for use during
hazardous waste trial burn tests and
ambient air measurements. RTI under
contract to the USEPA has responded to
this need through development of gas
cylinders containing 29 gaseous organic
compounds at ppb levels in compressed
gas cylinders. The gaseous compounds
are to be used in performance audits as
designated by the USEPA Project
Officer. These performance audits are to
assess the relative accuracy of source
measurement systems during hazardous
waste trial burn tests and ambient air
monitoring programs.
The audit materials currently contain-
29 compounds selected on the basis of
anticipated needs of USEPA's Office of
Solid Waste and Office of Air Quality
Planning and Standards. Table 1 lists the
five groups of compounds, the concen-
tration ranges, and the number of
cylinders in each group. The balance gas
for all gas mixtures is nitrogen and the
cylinder construction material is alu-
minum.
The gaseous compounds are ac-
quired from commercial suppliers in
compressed gas cylinders. These cylin-
ders, in conjunction with an appropriate
delivery system, are used directly as
sources of the gaseous compounds
during performance audits. The accuracy
of the supplier-reported levels of these
compounds is verified through mea-
surement of specially prepared standards
supplied by the National Bureau of
Standards (NBS) as compressed gas
mixtures in aluminum cylinders.
The accuracy of the cylinder
concentrations and the verification of
stability of the compounds in the cyl-
inders are important. Along with
Table 1. PPB Level Organic Gases Currently Available
Concentration Range
of Each Compound
Group No. of Cylinders (ppb)
Group 1*
Group ir
Group lir"
Group /V~*
Group V"""
29
12
12
12
6
14
3
12
6
6
7-90
90-430
430-10,000
7-90
90-430
7-90
90-200
7-90
430-10,000
1-40
" Group I Compounds: Carbon tetrachloride, chloroform,
tetrachloroethylene, benzene, and vinyl chloride.
" Group II Compounds: Trichloroethylene, 1,2-dich/oroethane,
1,2-dibromoethane, acetonitnle, trichlorofluoromethane
(F-11), dichlorodifluoromethane (F-12), bromomethane,
methyl ethyl ketone, and 1,1,1-trichloroethane.
*** Group III Compounds: PyridineV), Vinylidene Chloride, 1,1,2-
trichloro-1,2,2-trifluoroethane (F-113), 1,2-dichloro-
1,1,2,2-tetrafluoroethane (F-114), acetone, 1,4-dioxane,
toluene, and chlorobenzene.
(i)Pyridine concentrations are not certified due to analytical
problems
~" Group IV Compounds: Acrylonitrile, 1,3-butadiene, ethylene
oxide, methylene chloride, propylene oxide, and o-xylene.
"*"* Group V Compounds: Vinyl chloride, 1,3-butadiene,
bromomethane, trichlorofluoromethane (F-11), methylene
chloride, chloroform, 1,2-dichloroethane, 1,1,1-
trichloroethane, benzene, carbon tetrachloride, 1,2-
dichloropropane, trichloroethylene, toluene, 1,2-
dibromoethane, tetrachloroethylene, chlorobenzene,
ethylbenzene, and o-xylene.
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acquisition of new compounds and ver-
ification of their concentrations, an
extensive stability study is being per-
formed. This study involves periodic
analyses of the contents of the cylinder
gases that are currently available.
Procedure
Once a mixture of compounds is
chosen, a commercial supplier is
contacted to determine if a cylinder
containing the compounds of interest can
be prepared. If so, the manufacturer
prepares the cylinder gases and deter-
mines the concentration of the analytes
in the cylinder at least two times. The
cylinder is sent to RTI where its contents
are analyzed as soon as it arrives. The
gas mixtures are again analyzed at 2
months, 6 months, 12 months and on a
yearly basis following the initial analysis
to determine the stability of the gas
mixtures.
All recent analyses (1987) for Group
I, II, III, IV and V mixtures are performed
using a Nutech automated cryogenic
preconcentration apparatus with cryo-
focusing in conjunction with a Hewlett-
Packard 5880A gas chromatograph
equipped with flame lonization detector.
Previous analyses (prior to 1987) of all
the mixtures are performed by direct
injection instead of cryogenic precon-
centration. The gas chromatographic
parameters used in the measurement of
individual compounds in Group I, Group
II, Group III, Group IV and Group V are
described in the status report.
Compressed gas cylinder standard
mixtures obtained from NBS are used as
calibration standards for Group I, Group
II, Group III, Group IV and Group V A
different NBS standard was analyzed as
internal quality control on each day of
RTI analysis.
RTI supplies cylinder gases for
audits upon request from the USEPA,
state or local agencies or their
contractors. When a request is received,
the cylinder is then shipped by a freight
carrier to the laboratory being audited. A
letter is also included with the cylinder
which provides general instructions for
performance of the audit. The audit
concentrations are provided to the re-
questing agency Audit Coordinator. After
the laboratory being audited has anal-
yzed the contents of the cylinder, the
Audit Coordinator reports the value(s) to
RTI, which in turn reports both the
measured and accepted values to the
Project Officer. There is no charge for
the audit except the cost of returning the
audit cylinder.
Results and Discussion
To date, 198 performance audits
have been initiated; 172 are complete.
The results obtained are given in the
status report. Generally, the audit results
are within ± 50 percent of the audit
concentrations measured by RTI
Relative accuracies of the cylinder
gas analyses for Group I, Group II, Group
III, Group IV and Group V have been
determined using NBS primary stan-
dards. An examination of the data in the
status report to assess long-term sta-
bility shows that values for the
compounds in the Group I, Group II,
Group III, Group IV and Group V
cylinders vary by less than 10 percent
for 3 to 5 analyses over a one to three
year period. This variation indicates the
im-precision of the measurement
process. Precision of the measurement
process will be greatly enhanced once
the analytical system becomes fully
automated
The procedure used for the
determination of day-to-day mea-
surement uncertainty (repeatability) for
the five groups of compounds and es-
timates of uncertainty values are
presented in the status report.
Conclusions
Compressed gas cylinders contain-
ing 29 gaseous organic compounds at
parts-per-billion levels has been used
successfully in audits to assess the
relative accuracy and precision of anal-
ytical systems, especially those used
during hazardous waste trial burn tests
and ambient air monitoring. To date, 198
performance audits have been initiated
and 172 are complete. Generally the
audit results are within ± 50 percent of
the audit concentrations measured by
RTI
Stability studies for 29 gaseous
organic compounds included in the
cylinders have been performed to
determine the feasibility of using them as
audit materials. Results indicate that all
of the organics tested are stable enough
for use as reliable audit materials except
ethylene oxide and propylene oxide at
low concentrations.
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R.K.M. Jayanty, O.K. Sokol and C.E. Decker are with Research Triangle Institute,
Research Triangle Park, NC 27709.
Darryl J. von Lehmden is the EPA Project Officer (see below).
The complete Status Report #4, entitled "Stability of Parts-per-Billion
Hazardous Organic Cylinder Gases and Performance Audit Results of
Source Test and Ambient Air Measurement Systems," (Order No. PB
88-201 5041'AS; Cost: $25.95, subject to change) will be available only
from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
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 27711
•y
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
U.S.OFFICIALMAHL
Official Business
Penalty for Private Use $300
EPA/600/S4-88/016
6 c b 011) 9 i
. 0000329 PS
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