&EFK
United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
Research Triangle Park NC 2771 i
Research and Development
EPA/600/S4-87/007 June 1987
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 #3
J.M. Allen, C.K. Sokol, R.K.M. Jayanty, C.E. Decker and O.J. von Lehmden
An evaluation of 27 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
contractors by using ppb gas
cylinders 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 cylinder consists of four
mixtures of five, six, eight and nine
organic compounds each. These
mixtures were blended by a
commercial gas supplier in
aluminum cylinders in a balance gas
of nitrogen. The five-component
mixture (Group I) contains carbon
tetrachloride, chloroform, tetra-
chloroethylene (perchloroethylene),
vinyl chloride and benzene. The
nine-component mixture (Group II)
includes trichloroethylene, 1,2-
dichloroethane (ethylene
dichlorlde), 1,2-dibromoethane
(ethylene dibromide), acetonitrile,
trlchlorofluoromethane (F-11),
dichlorodifluoromethane (F-12),
bromomethane (methyl bromide),
methyl ethyl ketone and 1,1,1-
trichloroethane. The eight-
component mixture (Group III)
includes pyridine*. vinylldene
chloride, 1,1,2-trtchloro-1,2,2-
trifluoroethane (F-113), 1,2-
dlchloro-l,l,2,2-tetrafluoroethane
(F-114), acetone, 1,4-dloxane,
toluene, and chlorobenzene. The
six-component mixture (Group IV)
includes acrylonitrlle, 1,3-
butadiene, ethylene oxide,
methylene chloride, propylene oxide
and o-xylene. To date, 95
performance audits have been
initiated and 76 are complete. The
results of these audits and a
description of the experimental
procedures used for analyses and
"Although Group III cylinders contain
pygdine, the concentrations are not certified
due to severe analytical difficulties
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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 (RTt),
considering the low concentrations
of the organics and the anticipated
uncertainty associated with
independent analyses conducted
by an audit laboratory.
Stability studies for all Group I,
Group II and Group HI compounds
(except pyridine) have been
performed. Results indicate that all
the compounds tested are
adequately stable for use as
reliable audit materials. The Group
IV compounds will not be available
for audits until stability of the
compounds has been established.
If the data indicate that the Group
IV compounds are stable, Group IV
mixtures should be available for
audits on or after December 30,
1986.
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 27 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 27 compounds selected on the
basis of anticipated needs of USEPA's
Office of Solid Waste. Table 1 lists the
four groups of compounds, the
concentration ranges, and the number
of cylinders in each group. The balance
gas for all gas mixtures is nitrogen and
the cylinder construction material is
aluminum.
The gaseous compounds are
acquired from commercial suppliers in
compressed gas cylinders. These
cylinders, 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 measurement using
commercial permeation tubes or
specially prepared standards supplied
by the National Bureau of Standards
(NBS) as compressed gas mixtures in
aluminum cylinders. The permeation
rates of the commercially available
tubes are verified gravimetrically by
RTI before use.
The accuracy of the cylinder
concentrations and the verification of
stability of the compounds in the
cylinders are important. Along with
acquisition of new compounds and
verification of their concentrations, an
extensive stability study is being
performed. This study involves periodic
analyses of the contents of each of the
cylinders in the repository.
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 determines the
concentration of the analytes in the
cylinder at least two times. The
cylinder is sent to RTI where its
contents are analyzed, usually within
ten days of its arrival. If the RTI value
varies from the manufacturer's value by
more than 25 percent, reanalysis may
be performed by a third party (USEPA
or NBS). 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 analyses for Groups I, II and III
mixtures are performed using a
Hewlett-Packard 5880A gas
chromatograph equipped with flame
ionization and electron capture
detectors. The electron capture
detector (ECD) has been used
principally for measurement of all the
halogenated hydrocarbons except vinyl
chloride. Vinyl chloride, benzene,
methyl ethyl ketone, acetonitrile, all
Group III compounds, and all of the
Group I compounds in the high
concentration range cylinders are
analyzed with the FID. The gaseous
samples are injected onto the column
by means of two Valco six-port
sampling valves mounted near the
injection port. One valve is equipped
with interchangeable sampling loops (1
cc and 3 cc) to allow the injection of
different volumes of gas. The gas
chromatographic parameters used in
the measurement of individual
compounds in Group I, Group II and
Group III are described in the status
report. The gas chromatographic
parameters for the Group IV
compounds have not been established.
Permeation tubes are generally
used as calibration standards for all
Group I and Group II compounds. The
permeation rate of each permeation
tube is determined every 15 to 60 days
by weight-loss determination of each
tube. A compressed gas cylinder
standard mixture obtained from NBS is
used for the calibration standard for
Group III compounds. A similar NBS
standard will be used for the calibration
of Group IV compounds.
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 for the cost of returning the
audit cylinder.
Results and Discussion
To date, 95 performance audits
have been initiated; 76 are complete.
The results are given in the status three
report. Generally, the audit results are
within ±50 percent of the audit
concentrations measured by RTI.
Relative accuracies of the cylindei
gas analyses for Group I, Group II and
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Tabto 1. PPB Ural Organic QMM Currently AvaHabto
Group
Number of Cylinders
Concentration Ranoe of Each Compound (OOP)
Group I*
Group II"
Group Ill-
Group IV*
20
12
12
12
6
9
3
12
6
7-90
90-430
430-10.000
7-90
90-430
7-90
90-430
7-90
430-10.000
Group I Compounds: Carbon tetrachtoride. chloroform, tetracNoroethytene (perchtoroetnytene), vinyl chloride and benzene.
Group II Compounds: Trichloroethvtene, 1,2-dichtoroethane. 1,2-dibromoethane, acetonitrile, trichlorofluoromethane (F-11),
dichlorodifluoromethane (F-12). bromomethane, methyl ethyt ketone, and 1,1,1-trichtoroethane.
Group III Compounds: Pyridine, VinyWene 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 cNorobenzene.
Group IV Compounds: Acrytonrtrite, 1,3-butadiene, ethylene oxide, methytene chloride, propytene oxide, and o-xytene. These cylinders
should be available tor performance audits on or after December 30,1986.
Group III compounds 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 the Group I, Group II
and Group III repository cylinders vary
by less than 10 percent for 3 to 5
analyses over a one-year period. This
variation indicates the imprecision of
the measurement process. The
possible sources of experimental error
that could contribute to this variability
include: (1) the variability of the
sampling injection technique used for
analyses; and (2) the instrumental
variability in operating and detector
parameters. Each of these sources of
variability contributes to the net
uncertainty of the resulting stability
data. Estimates of total uncertainty
(repeatability) for Group I compounds
have been determined to be in the
range of 2.1-3.2% (coefficient of
variation) at 95% confidence limits. The
estimate of total uncertainty for Group II
compounds has been determined to be
in the range of 3.4-7.0% (coefficient of
variation) at 95% confidence limits. The
total uncertainty for the Group III
compounds with the exception of
acetone and 1,4-dioxane has been
determined to be in the range of 9-
12% (coefficient of variation) at 95%
confidence limits. Acetone and 1,4-
dioxane initially had quite high total
uncertainties in the range of 30-50%
(coefficient of variation) at 95%
confidence limits, due to difficulties in
the analysis of these two compounds.
The analytical difficulties from which
those high uncertainties arose have
been partially resolved. The total
uncertainties for acetone and 1,4-
dioxane are presently in the range of
30-32% (coefficient of variation) at
95% confidence limits. The stability of
a compound may be suspect if a
change in concentration over time is
noted that exceeds the 95% confidence
limits. An examination of such data
indicates that the Groups I, II. and III
compounds in the repository cylinders
have continued to remain stable.
Conclusions
Compressed gas cylinders
containing 27 gaseous organic
compounds at parts-per-billion levels
has been used successfully in audits to
assess the relative accuracy and
precision of analytical systems,
especially those used during hazardous
waste trial bum tests and ambient air
monitoring. To date. 95 performance
audits have been initiated and 76 are
complete. Generally the audit results
are within ±50 percent of the audit
concentrations measured by RTI.
Stability studies for 21 of the 27
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. The Group IV
compounds will not be available for
audits until the stabilities of the
compounds have been established. If
the data indicate that the Group IV
compounds are stable. Group IV
mixtures should be available for audits
on or after December 30,1986.
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J. M. Allen. C. K. Sokol, R. K. M. Jayanty, and C. E. Decker are with Research
Triangle Institute. Research Triangle Park, NC 27709; the EPA author Darryl
J. Von Lahmden (also the EPA Project Officer, see below) is with the
Environmental Monitoring Systems Laboratory Research Triangle Park, NC
27711.
The complete report, entitled "Stability of Parts-Per-Billion Hazardous Organic
Cylinder Gases and Performance Audit Results of Source Test and Ambient
Air Measurement Systems—Status Report #3," (Order No. PB 87-168 8037
AS; Cost: $18.95, 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
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S4-87/007
0000329 PS
S
60604
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