United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S2-86/003 Mar. 1986
&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 #2
R.K.M. Jayanty, S.W. Cooper, J. Sokash, C.E. Decker, and D. J. von Lehmden
A feposttoiy of 22 gaseous organic
compounds at parts-per-biHion fppfa)
Jewels in compressed gas cylinders has
been established undw a cuniiact wilfi
1he EnwuMiHMnUi Protection Agency
{EPA}. The primary objecUnes of this
ongoing project vmr. W to provide
accurate gas mixtures to EPA, state/
local agencies, or their contractors for
performance audits to assess the rela-
tive accuracy of source measurement
systems during hazardous waste trial
burn tests and ambient air monitoring
programs; (2) to verify the manufac-
turer's certified analysis of the multi-
component gas mixtures; (3) to deter-
mine the stability of the gas mixtures
with time; and (4) to develop new audit
materials as requested by EPA.
The repository consists of three wn*-
tures of five, eight and nine m&ariic
compounds each. These mixtures'siwrs
blended by a commercial gas supplier
in aluminum cylinders in a bs1 lance
gas of nitrogen. The five component
mixture (Group I) contains carbon
tetrachloride, chloroform, perchloro-
ethylene, vinyl chloride and benzene.
The nine component mixture (Group II)
includes trichloroethylene, 1,2-di-
chloroethane, 1,2-dibromoethane,
acetonitrile, trichlorofluoromethane
(F-11), dichlorodifluoromethane (F-
12), bromomethane, 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-frilUioroethane
JF-113), 1,2- dichloro 1,f,2,2-tetra-
fluoroethane (F-114). acetone, 1,4-
dtoxane, toluene, and chlorobenzene.
To date 41 performance audits Hauee
been initiated and 35 are compJfete.
The results of these audits and a de-
scription of the experimental proce-
dures wsed for analyses and available
stability data are presented in the full
status report. Generally, the results of
the audits show reasonable agreement
(plus or minus 50 percent) with the
audit material concentrations mea-
sured by Research Triangle Institute,
considering the low concentrations of
the organics and the anticipated uncer-
tairtty associated vwtth independent
•analyses conducted *by an audit labor-
atory.
Stability studies tor all Group I and
'Group 'II compounds have been per-
formed. Results indicate that all the
compounds tested are adequately
stable for usesrs reliable audit mate-
rials. The Group III compounds will not
be available for audits until stability
of the compounds has been established.
If the data indicate that the Group III
compounds are stable. Group III mix-
tures should be available for audits
on or after December 1, 1985.
This Project Summary was devel-
-------
oped by EPA's Environmental Monitor-
ing Systems Laboratory, Research
Triangle Park, NC, to announce key
findings of the research project that is
fully documented.™ 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 EPA's
Environmental Monitoring Systems Lab-
oratory has initiated a program to supply
audit materials for use during hazardous
waste trial burn tests and ambient air
measurements. The Research Triangle
Institute (RTI), under contract to the
Environmental Protection Agency (EPA),
has responded to this need through
development of a repository of 22 gas-
eous, organic compounds at parts-per-
billion (ppb) levels in compressed gas
cylinders. The gaseous compounds are to
be used in performance audits as desig-
nated by the EPA 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 repository currently contains 22
compounds selected on the basis of
anticipated needs of EPA's Office of Solid
Waste. Table 1 lists the 22 compounds,
the concentration ranges, and the number
of cylinders for each group in the reposi-
tory. 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 com-
pressed gas cylinders; these same cyl-
inders, along with an appropriate delivery
system, are used directly as sources of
the gaseous compounds during per-
formance audits. The accuracy of the
supplier-reported levels of these com-
pounds is verified through measure-
ment using commercial permeation
tubes. The permeation rates of the com-
mercially available tubes are verified
gravimetrically by RTI before use.
The accuracy of the "known" cylinder
concentrations and the verification of
stability of the compounds in the cyl-
inders are important. Along with acquisi-
tion 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.
Table 1. PPB Level Organic Gases in Repository
Group No. of Cylinders
Concentration Range of
Each Compound (ppb)
Group I*
Group //**
Group ///***
20
12
12****
12
3
7-90
90-430
430-10,000
7-90
90-430
7-90
* Group I Compounds: Carbon tetrachloride, chloroform, perchloroethlyene, vinyl chloridi
and benzene.
** Group II Compounds: Jrichloroethylene, 1,2-dichloroethane, 1-2-dibromoethane
acetronitrile. trichlorofluoromethane (F-11). dichlorodifluoromethane (F-12)
bromomethane, methyl ethyl ketone, and 1,1.1 -trichloroethane.
*** Group III Compounds: Pyridine, Vinylidene Chloride, 1,1,2-trichloro 7,2,2
trifluoroethane (F-113), 1,2-dichloro 1.1,2.2-tetrafluoroethane (F-114), acetone. 1,4
dioxane, toluene, andchlorobenzene.
*»*» fhese cylinders will become available for performance audits on or after December 1.
1985.
Procedure
Once a mixture of compounds is
chosen, a commercial supplier is con-
tacted to determine if a cylinder contain-
ing those compounds can be prepared.
If so, the manufacturer prepares the
cylinder gases and determines the con-
centration of the analytes in the cylinder
by 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, re-
analysis may be performed by a third
party (EPA or NBS). The gas mixtures are
again analyzed at 2 months, 6 months,
12 months and 18 months following the
initial analysis to determine the stability
of the gas mixtures.
All analyses for Group I and II mixtures
are performed using a Hewlett-Packard
5880A gas chromatograph equipped
with flame ionization and electron cap-
ture detectors. The electron capture
detector (ECD) has been used prin-
cipally for measurement of all the
halogenated hydrocarbons except vinyl
chloride. Vinyl chloride, benzene, methyl
ethyl ketone and acetonitrile are analyzed
with flame ionization detector (FID). The
gaseous samples are injected onto the
columns by means of a high-speed
six-port gas sampling valve (Seiscor
Valve Model AN 100A) mounted near the
injection port. The valve is equipped with
interchangeable sampling loops (1 ccand
10 cc) to allow the injection of variable
but known volumes of gas. The gas
chromatographic parameters used in the
measurement of individual compound
in Group I and Group II are described i
the full status report. The gas chromatc
graphic para meters for the Group Illcorr
pounds have not been established. Th
development of cryofocusing on capillar
column for the analysis of Group I
compounds is in progress and the detail
will be presented in a future report.
Permeation tubes purchased fror
Metronics are generally used as calibra
tion standards for all 22 organic con-
pounds unless otherwise specified. Th
permeation rate of each permeation tub
is determined every 15 to 30 days b
weight-loss determination of each tube
The RTI supplies repository cylinder
for audits upon request from the EP/
state or local agencies or their contrac
tors. When a request is received, th
cylinder is then shipped by a freigh
carrier to the laboratory being auditec
A letter is also included with the cylinde
which provides general instructions fc
performance of the audit. The audit con
centrations are provided to the request
ing agency Audit Coordinator. After th
laboratory being audited has analyze
the contents of the cylinder, the Aud
Coordinator reports the value(s) to RT
which in turn reports both the measure
and accepted values to the Projec
Officer. There is no charge for the aud
except the cost of returning the aud
cylinder.
Results and Discussion
To date, 41 performance audits hav
been initiated, and 35 are complete. Th
-------
esults are given in the full status report.
Generally, the audit results are within
± 50 percent of the audit concentrations
measured by RTI.
Most of the cylinders in the repository
are analyzed three to five times to deter-
mine the stability of the compounds.
Relative accuracies of the cylinder gas
analyses for Group I and Group II com-
pounds have been determined using NBS
primary standards. An examination of
stability data in the status report shows
values for Group I and Group II individual
cylinder gas analyses usually vary by less
than 10 percent for 3 to 5 a nalyses over a
one-year period. This variation indicates
the imprecision of the measurement
process. The possible sources of experi-
mental error that could contribute to this
variability include: (1) the variability of
the sampling injection technique used for
analyses; and (2) the instrumental vari-
ability in operating and detector param-
eters. 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
estimates 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.
Conclusions
A repository of 22 gaseous organic
compounds at parts-per-billion levels in
compressed gas cylinders has been used
successfully in audits to assess the rela-
tive accuracy and precision of analytical
systems, especially those used during
hazardous waste trial burn tests and
ambient air monitoring.
Stability studies for 14 gaseous or-
ganic compounds have been performed
to determine the feasibility of using them
as audit materials. Results indicate that
all of the organics tested are adequately
stable to be used as reliable,audit
materials. The Group III compounds will
not be available for audits until stability
of the compounds have been established.
If the data indicate that the Group III
compounds are stable. Group III mixtures
should be available for audits on or after
December 1, 1985.
R. K. M. Jayanty. S. W. Cooper, J. Sokash. and C. E. Decker are with Research
Triangle Institute, Research Triangle Park, NC 27709.
DarrylJ. von Lehmden is the EPA Project Officer (see below).
The complete report, entitled "Stability of Parts-Per-Billion Hazardous Organic
Cylinder Gases and Performance A udit Results of Source Test and Ambient Air
Measurement Systems—Status Report #2." (Order No. PB 86-144 656/AS;
Cost: $16.95, 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, NC27711
-------
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S2-86/003
0000329 PS
U S SNVIR PROTECTION AGENCY
REGION 5 LIBRARY
230 S DEARBORN STREET
CHICAGO If. 60604
------- |