United States
Environmental Protection
Agency
Atmospheric Research and
Exposure Assessment Laboratory N '
Research Triangle Park NC 27711 -'
Research and Development
EPA/600/S3-89/014 Aug. 1989
Project Summary
Status Report #5,
Stability of Parts-Per-Billion
Hazardous Organic Cylinder
Gases and Performance Audit
Results of Source Test and
Ambient Air Measurement
Systems
V. R. Bryant, G. 8. Howe, S. B. Tompkins,.and R.K.M. Jayanty
An evaluation of 29 gaseous
organic compounds at parts-per-
billion (ppb) levels in compressed
gas cylinders has been established
by 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
contractors by using ppb gas cylin-
ders for performance audits to
assess the relative accuracy of
source measurement 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 aluminum
cylinders in a balance gas of
nitrogen. The five component mix-
ture (Group I) contains carbon tetra-
chloride, chloroform, tetrachloro-
ethylene (perchloroethylene), vinyl
chloride and benzene. The nine com-
ponent mixture (Group R) includes trl-
cnloroethylene, 1,2-dichloroethane
(ethylene dichloride), 1,2-dibromo
ethane (ethylene dibromide),
acetonitrile, trichlorofluoromethane
(F-11), dichlorodifluoromethane (F-I2),
bromomethane (methyl bromide),
methyl ethyl ketone, and 1,1,1-tri-
chloroethane. The eight component
mixture (Group III) includes pyridine*.
vinylidene chloride, 1,1,2-trlchloro-
1,2,2-trifluoroethane (F-113), 1,2-di-
cnloro-1,1,2,2-tetrafluoroethane (F-
114), acetone, 1,4-dioxane, toluene,
and chlorobenzene. The six compo-
nent mixture (Group IV) includes
acrylonitrile, 1,3-butadiene, ethylene
oxide, methylene chloride, propylene
oxide, and o-xylene. The eighteen-
component mixture (Group V)
includes vinyl chloride, 1,3-butadiene,
bromomethane, trichlorofluoro-
methane (F-11), methylene chloride,
"Although Group III cylinders contain pyridine, the
concentrations are not certified due to severe
anylitical conditions.
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chloroform, 1,2-dichloroethane,
1,1,1-trichloroethane, benzene,
carbon tetrachloride, 1,2-dichloro-
propane, trichloroethylene, toluene,
1,2-dibromoethane, tetrachloro-
ethylene, chlorobenzene, ethyl-
benzene, and o-xylene. To date, 268
performance audits have been
initiated and 247 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 (plus or minus
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
independent analyses conducted by
an audit laboratory.
Stability studies for ail Group I,
Group II, Group III (except pyridine),
Group IV and Group V compounds
have been performed. Results
indicate that all the compounds
tested are adequately stable for use
as reliable audit materials with the
exception of ethylene oxide and pro-
pylene oxide at low concentrations.
This Project Summary was
developed by EPA's Atmospheric
Research and Exposure Assessment
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
Atmospheric Research and Exposure
Assessment Laboratory has initiated a
program to supply audit materials for use
during hazardous waste trial burn tests
and ambient air measurements.
Research Triangle Institute (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
Table 1. PPB Level Organic Gasses
Currently Available.
Concentration
No. of range of each
Group
Group 1
Group II
Group III
Group IV
cylinders
26
11
12
12
6
14
3
12
6
compound (ppb)
7-90
90-430
430-10.000
7-90
90-430
7-90
90-430
7-90
430-10,000
Group V
11
1-40
• Group I Compounds: Carbon
tetrachloride. chloroform, tetrachloro-
ethylene, benzene, and vinal chloride.
• Group II Compounds: Trichloroethylene,
1,2-dichloroethane, 1,2-dibromo-
ethane, acetomtrile, tnchlorofluoro-
methane (F-11), dichlorodiflouro-
methane (F-12), bromomethane, methyl
ethyl ketone, and 1,1,1-trichloroethane.
• Group III Compounds: Pyridine(1>,
vinylidene chloride, 1,1,2-tnchloro-
1,2,2-tnfluoroethane (F-113), 1,2-di-
chloro-i, 1,2,2-tetrafluoroethane (F-
114), acetone, 1,4-dioxane, toluene,
and chlorobenzene.
• 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, tri-
chlorofluoromethane (F-11), methylene
chloride, chloroform, 1,2-dichloro-
ethane, i.t.t-tnchloroethane, benzene,
carbon tetrachloride, chlorobenzene,
ethylbenzene, and o-xylene
concentrations are not certified
due to analytical problems.
waste trial burn tests and ambient air
monitoring programs.
The audit materials currently consist of
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 con-
centration ranges, and the number of
cylinders in each group. The balance
gas for all gas mixtures is nitrogen and
the cylinder construction material
aluminum.
The gaseous compounds are acquir<
from commercial suppliers in cor
pressed gas cylinders These cylindei
in conjunction with an appropria
delivery system, are used directly ;
sources of the gaseous compounc
during performance audits. Tr
accuracy of the supplier-reported leve
of these compounds is verified throuc
comparison with specially prepare
standards supplied by the Nation
Bureau of Standards (NBS) as con
pressed gas mixtures in aluminu
cylinders.
The accuracy of the cylinder conce
trations and the verification of stability
the compounds in the cylinders ai
important. Along with acquisition of ne
compounds and verification of their coi
centrations, an extensive stability study
being performed. This study involve
periodic analyses of the contents of tr
cylinder gases that are currentl
available.
Procedure
Once a mixture of compounds
chosen, a commercial supplier
contacted to determine if a cylind<
containing the compounds of interest a
be prepared. If so, the manufactun
prepares the cylinder gases an
determines the concentration of th
analytes in the cylinder at least tw
times. The cylinder is sent to RTI whei
its contents are analyzed as soon as
arrives. The gas mixtures are agai
analyzed at 2 months, 6 months, 1
months and on a yearly basis followin
the initial analysis to determine th
stability of the gas mixtures.
All analyses (1987 and after) fc
Groups I, II, III, IV, and V mixtures ai
performed using a Nutech automate
cryogenic preconcentration apparatu
with cryofocusmg in conjunction with
Hewlett-Packard 5880A gas chromatc
graph equipped with flame ionization an
electron capture detectors. Previou
analyses (prior to 1987) of all th
mixtures were performed by direc
injection instead of cryogenic precor
centration. The gas chromatographi
parameters used in the measurement <
individual compounds in Group I, Grou
II, Group III, Group IV, and Group V ar
described in the complete status report.
Compressed gas cylinder standar
mixtures obtained from NBS are used a
calibration standards for Groups I, II, II
IV, and V. A different NBS standard ws
analyzed as internal quality control o
each of the RTI analysis days.
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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 requesting agency Audit
Coordinator. After the laboratory being
audited has analyzed 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, 268 performance audits have
been initiated; 247 are complete. The
results obtained are given in the status
report. Generally, the audit results are
within ± 50 percent of the audit con-
centrations measured by RTI.
Relative accuracies of the cylinder gas
analyses for Groups I, II, III, IV, and V
have been determined using NBS
primary standards. An examination of
the data in the status report to assess
long-term stability shows that values for
the compounds in Group I, Group II,
Group III, Group IV, and Group V
cylinders vary by less than 10 percent
for 3 to 7 analyses over a one to five
year period. This variation indicates the
imprecision of the measurement process.
The procedure used for the deter-
mination of day-to-day measurement
uncertainty (repeatability) for the five
groups of compounds and estimates of
uncertainty values are presented in the
status report.
Conclusions
Compressed gas cylinders containing
29 gaseous organic compounds at
parts-per-billion levels have been used
successfully in audits to assess the
relative accuracy and precision of
analytical systems, especially those used
during hazardous waste trial burn tests
and ambient air monitoring. To date, 268
performance audits have been initiated
and 247 are complete. Generally the
audit results are within q 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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V. R. Bryant, G. B. Howe, S. B. Tompkins, and R. K. M. Jayanty are with Research
Triangle Institute, Research Triangle Park, NC 27709.
Darryl von Lehmden is the EPA Project Officer (see below).
The complete report, entitled "Status Report #5, Stability of Parts-per-Billion
Hazardous Organic Cylinder Gases and Performance Audit Results of Source
Test and Ambient Air Measurement Systems" (Order No. PB 89-155 2381 AS;
Cost: $36.95, 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:
Atmospheric Research and Exposure Assessment Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States Center for Environmental Research
Environmental Protection Information
Agency Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S3-89/014
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