United States
 Environmental Protection
 Agency
 Environmental Monitoring Systems
 Laboratory
 Research Triangle Park NC 27711
 Research and Development
 EPA-600/S4-82-064  Jan. 1983
 Project  Summary
 Stability  of  Organic  Audit
 Materials  and  Results of
 Source Test  Analysis  Audits
 R. K. M. Jayanty, W. F. Gutknecht, C. E. Decker, J. E. Knoll, and D. J.
 von Lehmden
  A  repository  of 40 gaseous
 compounds including  hydrocarbon,
 halocarbon, and sulfur species has
 been established under contract with
 the U.S. Environmental Protection
 Agency (USEPA). The main objectives
 of this on-going  project are  (1) to
 provide gas mixtures to EPA,  state/
 local agencies, or their contractors, as
 performance audits to  assess  the
 accuracy  of source  emission
 measurements  in  certain  organic
 chemical  manufacturing industries,
 (2)  to  corroborate  the vendor's
 certified analysis of the gas mixtures
 by in-house analysis, (3) to determine
 the stability of the gas mixtures with
 time by in-house analysis, and (4) to
 explore the feasibility of new audit
 materials as requested by EPA.
  Thus far, 18 compounds have been
used to conduct 86 different audits.
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. Seventy percent
of the  audit results are  within  10
percent of the expected values.
  Compound stabilities  have been
 determine through multiple analyses
 of the cylinders  containing  them.
 Stability values for all compounds are
 expressed as  percent change  per
 month.  Calculated  changes  are
 typically found to be a few tenths of
 one percent per month, though many
 of these changes may not be signifi-
 cantly different from zero.
   This Project Summary was devel-
 oped  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
   Accurate  measurement  of  hydro-
 carbons,  halocarbons,  and   sulfur-
 containing compounds in ambient and
 source samples  is essential to any
 environmental  monitoring  program.
 The potential for achieving acceptable
 accuracy is enhanced by the availability
 of reliable standards which can be used
 to check or  validate the measurement
 process. The  Research Triangle
 Institute (RTI) under contract  to the
 Environmental  Monitoring  Systems
 Laboratory, U.S.  Environmental
 Protection  Agency (USEPA),  has
 responded to this need by developing an
 extensive  repository  of standard
i gaseous compounds. These standards
 are to be used in performance audits as
 designated by the EPA Project Officer.
 These performance audits are to assess
 the  accuracy of  source emission
 measurements  in  certain   organic
 manufacturing industries.
  The RTI repository currently contains
 40 different compounds based on
 anticipated needs of EPA. Table 1 lists
 the  compounds,  the . concentration
 ranges  of each compound,  and the

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  Table 1.  Audit Materials Currently Held in the Repository
                         Low Concentration Range   High Concentration Range
     Compound
 No. of
Cylinders
Concentration
 Range (ppm)
 No. of
Cylinders
Concentration
 Range (ppm)
Benzene                   14
Ethylene                    4

Propylene                   4
Methane/Ethane

Propane                     4
Toluene                     2
Hydrogen Sulfide             4
Meta-Xylene                 2
Methyl Acetate               2
Chloroform                  2
Carbonyl Sulfide              2
Methyl Mercaptan            4
Hexane                     2
1,2-Dichloroethane           4
Cyclohexane
Methyl Ethyl Ketone          1
Methanol                   1
1.2-Dichloropropane          2
Trichloroethylene             2
 1,1 -Dichloroethylene         2
 1,2-Dibromoethylene         2
Perchloroethylene            2
 Vinyl Chloride               9
 1,3-Butadiene               1
Acrylonitrile                 2
Aniline                     1
Methyl Isobutyl Ketone       1
Cyclohexanone               2
Para-dichlorobenzene         2
Ethylamine                  2
Formaldehyde
Methylene Chloride          1
Carbon Tetrachloride         1
 Freon 113                  1
 Methyl Chloroform           1
 Ethylene Oxide              1
 Propylene Oxide             1
Allyl Chloride               1
Acrolein                    1
 Chlorobenzene               1
 Carbondisulfide              1
              8- 13
              5-20

              5-20
                  17
                   4
                   6
                   4
                   4
            60
           300
         3000
           300
          WOO
           200
           300
           300
           300
           300
           300
           300
           100
    -400
    - 700
    - 20.000
    - 700
    - 6000(MJ,
    - 700(E)
    - 700
    -700
    -700
    -700
    •700
    -700
    -300
number of cylinders of each compound.
Additional compounds are obtained as
needed.
  The gaseous compounds are acquired
from  commercial  suppliers  in
compressed gas cylinders; these same
cylinders,  along  with an  appropriate
delivery system,  are used  directly as
sources of the  standard  gas  during
performance  audits.  The compressed
gas cylinder is especially suitable as an
audit material because of its simplicity,
portability, low cost, flexibility in analyte
delivery over a  broad concentration
              5-20         4
              5-20         2
              5-20         2
              5-20         2
              5-20         2
              5-20         2
              5-20         2
              3-10         -          	
             20-80         2     1000 • 3000
              5-20         4      100-600
              	          /          700
               50           -           	
               50           -          	
              5-20         2      300 - 700
              5-20         2      100-600
              5-20         2      100-600
              5-20         2      100- 600
              5-20         2      300 - 700
              5-30         -        	
               25           -        	
              5-20         2      300-700
               10           -        	
               10           1       50 - 100
              5-20         .        	
             10-40         -        	
             10 - 60         -        	

                10           -        	
                10           -        	
                10           -        	
                10           -        	
                10           -        	
              5-20         1       75 - 200
              5-20         /       75-200
              5-20         1       75-200
              5-20         -        	
              5-20	1	75-200

               range, reliability, and ruggedness for
               interstate shipping. The accuracy of the
               supplier-reported  levels  of  these
               compounds  are  verified  through
               measurement using National Bureau of
               Standards  -  Standard  Reference
               Materials  (NBS-SRM's),  commercial
               permeation  tubes,   and/or  reagent
               grade pure liquids as standards. The
               permeation rate of  the commercially
               available tubes are verified by RTI before
               use.
                  The accuracy of the "known" cylinder
               concentrations and the 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 performed. This study involves
periodic  analyses of the contents of
each of the cylinders in the repository.

Procedure
  Once a  compound  is  chosen, a
commercial supplier  is contacted  to
determine if a cylinder containing that
compound can be prepared. If so,  the
manufacturer  prepares the  cylinder
gases and determines the concentra-
tion of the analyte in the cylinder. The
cylinder is sent to RTI where its contents
are analyzed  within seven days of its
arrival. If the RTI value varies from the
manufacturer's value by more than 10
percent, an analysis is performed by a
third party. The cylinder contents  are
then   analyzed   one  month  after
acquisition,  two  months after
acquisition, and one year after acqui-
sition.  The cylinder contents are also
analyzed before a cylinder is sent out for
an audit.  This preaudit analysis  may
substitute for the annual  analysis  if it
occurs within  a  month of the normal
analysis due date.
  All analyses are carried out using gas
chromatography.  The  column  and
detector are chosen so as to be optimum
for the compound  being measured.
Three types of standards are used to
generate gas  concentrations  for
calibration of the  GC for the measure-
ment   of  audit   materials.  National
Bureau  of   Standards  -   Standard
Reference  Materials (NBS-SRM)
methane  and propane are used  as
standards for  the  measurement  of
methane and propane audit materials.
These same gases are used to calibrate
the  chromatographic system  for
measurement   of  ethylene  and
propylene, assuming the FID response
per carbon is constant for compound to
compound. In  a few others (e.g., vinyl
chloride,  ethylene   oxide)   gaseous
standards  are  generated  using
permeation tubes. The standards  for
most  of the other audit materials are
prepared using pure liquids which are
volatized in a clean glass bulb.
   Audit requests are directed to  RTI
through  the  EPA Project Officer.  The
cylinder and  a  regulator  are  then
shipped  by a  freight  carrier to  the
laboratory being audited. A letter is also
included  with  the  cylinders which
provides general  instructions   for

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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.  The laboratory
being audited then is  responsible for
shipping the cylinder and regulator back
to RTI.
Results and Discussion
  To date,  86 individual audits have
been initiated, and 83 are complete. The
results  obtained  for  a  few  typical
performance audits are shown in Table
2 and the rest are given in the full report.
Generally,  the  results of the audits
show close agreement (±.10%) with the
actual  cylinder  concentrations
measured prior to shipment.
  Most of the cylinders in the repository
are analyzed at  least four  times to
determine  the  stability  of  these
compounds; some are analyzed as many
as eight times. An estimate of stability
has been made for each cylinder that

Table 2.   Typical Audit Results
               has been analyzed at least three times.
               This estimate is a calculation of percent
               change in concentration per month over
               the period that RTI  has performed
               analyses of the cylinder contents. The
               calculation involves a linear regression
               analysis  of the  concentration  of the
               analyte versus time in days. The slope
               and  intercept  determined  by  this
               regression analysis are then  used  to
               calculate percent change per month  by
               the relationship:
                                        slope
                                          % Change/Month =
                                    y  intercept
                                    100x30
               Examples of stability data are shown in
               Table 3. Changes are noted  for each
               compound,  although   these  changes
               may not be significantly different from
               zero.  As the number of analyses per
               cylinder increases, additional statistical
               analyses will be performed.

               Conclusions
                Cylinder  gases  of  hydrocarbons,
               halocarbons, and sulfur  species have
               been  used successfully to assess the
     Industry
Audit Material
   Cylinder
Concentration  Client Audit
    (ppm)      Accuracy
Maleic anhydride
production
Ester production
Vegetable oil plant
Coke oven by-product
Benzene in N
Propane in Air
Hexane in N
Benzene in N
138
300
10.1
710
82.2
1982
88.4
8.2
-9.4
+4.7
+8.6
+8.6
+5.6
+3.0
-8.7
+2.6
accuracy  of  gas   chromatographic
systems  used  to  measure  organic
compounds  in  source emissions.
Absolute  accuracy  has  not  been
determined because of lack of standard
reference materials; instead, interlabor-
atory bias has been reported for the
performance  audits conducted during
source testing. The interlaboratory bias
determined has been generally within
10  percent  for  both  low  and  high
concentration gases.
  Twenty-six   out  of  40  gaseous
compounds  have demonstrated
sufficient stability in cylinders for use as
audit  materials.  Four  compounds
(ethylamine,  paradichlorobenzene,
cyclohexanone,  and  aniline) are  not
recommended as audit materials for
various reasons as discussed in the full
report. Another 10 compounds (carbon
tetrachloride,  methylene chloride,
methyl chloroform, Freon 113, ethylene
oxide,  propylene  oxide, alkyl chloride,
acrolein,  ch lorobenzene  and
carbondisulfide)  have  recently been
added to the repository; the stability of
these  compounds  remains   to   be
studied. The estimates of stability are
reported in terms of percent change per
month.  Detailed  statistical  analyses
which  would  separate  statistical
deviations  from  true  concentration
change with time are in progress and
will   be presented   in  a   journal
publication.
Table 3.   Typical Stability Results
  Compound
  Concentration  Period of Cylinder
     (ppm)     Analyses (months)  % Change/Month
Benzene
Benzene
Hydrogen sulfide
1,2 Dichloroethane
Perchloroethylene
Acrylonitrile
Chloroform
Propylene
12.2
296
9.15
439
13.0
20.1
348
14.8
25
27
37
28
13
28
33
25
-0.15
0.01
-0.05
-0.10
-0.23
-1.07
-0.20
0.06

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      R. K. M. Jayanty, W. F. Gutknecht, and C. E. Decker are with Research Triangle
        Institute, Research Triangle Park, NC 27709; the EPA authors J. E. Knoll and
        D. J. von Lehmden (also the EPA Project Officer, see below) are with the
        Environmental Monitoring Systems Laboratory, Research Triangle Park, NC
        27711.
      The complete report, entitled "Stability of Organic Audit Materials and Results
        of Source Test Analysis Audits," (Order No. PB 83-107 490; Cost: $11.50.
        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
                                                                    •(t U.S. GOVERNMENT PRINTING OFFICE: 1983	 6S9-O17/O881:
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