&EFA
United State*
Environmental Protection
Agency
Environmental Monitoring and Support EPA-600/4-79-025
Laboratory March 1979
neiearch Triangle Park NC 27711
Development
Evaluation of
Emission Test
Methods for
Halogenated
Hydrocarbons
Volume I
CCU,
CzHCIa
, and
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•3
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development. U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface ..in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL MONITORING series.
This series describes research conducted to develop new or improved methods
and instrumentation for the identification and quantification of environmental
pollutants at the lowest conceivably significant concentrations. It also includes
studies to determine the ambient concentrations of pollutants in the environment
and/or the variance of pollutants as a function of time or meteorological factors.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EVALUATION OF EMISSION TEST METHODS FOR HALOGENATED
HYDROCARBONS - VOLUME I, CC14, C^Clg, C2C14 an C2HC13
by
Joseph E. Knoll, Mark A. Smith, and M. Rodney Midgett
Quality Assurance Branch
Environmental Monitoring and Support Laboratory
Research Triangle Park, North Carolina 27711
ENVIRONMENTAL MONITORING AND SUPPORT LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, NORTH CAROLINA 27711
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DISCLAIMER
This report has been reviewed by the Environmental Monitoring and Support
Laboratory, U.S. Environmental Protection Agency, and approved for publication.
Mention of trade names or commercial products does not constitute endorsement
or recommendation for use.
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ABSTRACT
Carbon tetrachloride, ethylene dichloride, tetrachloroethylene, and tri-
chloroethylene in compressed gas mixtures stored in aluminum and steel
cylinders remained stable for 4 months when maintained at ambient temperatures.
Tedlar bags were also evaluated as containers for gaseous mixtures of these
four compounds at source-level concentrations. Carbon tetrachloride and
tetrachloroethylene samples remained stable for 10 days, trichloroethylene
for 2 days, and ethylene dichloride for 1 day. Storage at -25°C did not
cause concentration changes; heating did cause changes. When Tedlar bags
containing the subject gas mixtures were heated to 70°C, carbon tetrachloride,
tetrachloroethylene, and trichloroethylene samples remained stable for 64, 8,
and 5 hr, respectively. Heating ethylene dichloride gas mixtures in Tedlar
bags to 60°C caused important concentration changes after only 1 hr. A pro-
cedure was developed to remove persistent residues from Tedlar bags that had
contacted high concentrations of halo-genated hydrocarbons. This procedure
consisted of flushing the bag with nitrogen, heating to 60°C, and flushing
again. Only residues of ethylene dichloride could not be removed by this
technique. Retention indices of several columns that may be used for the
analysis of chlorinated hydrocarbons were also determined.
iii
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CONTENTS
Abstract iii
Figures v
Tables vi-vii
Abbreviations and Symbols viii
Acknowledgment ix
1. Introduction 1
2. Conclusions. 4
3. Experimental 6
4. Results and Discussion 10
References 36
IV
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FIGURE
Number Page
1 Double Tedlar bag assembly 9
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TABLES
Number Page
1A Time Variation of Concentrations of Chlorinated Hydro-
carbons in Cylinders 11
IB Time Variation of Concentrations of Chlorinated Hydro-
carbons in Cylinders 12
2 Measured Rates of Concentration Change of Chlorinated
Hydrocarbon Cylinder Gases 13
3 Variation of CC1, Concentration of Gas Mixture Stored
in Tedlar Bags at Ambient Temperatures 22
4 Variation of CpCl* Concentration of Gas Mixtures Stored
in Tedlar Bags at Ambient Temperatures 23
5 Variation of CpCHl, Concentration of Gas Mixtures Stored
in Tedlar Bags at Ambient Temperatures 24
6 Variation of CoH^Clp Concentration of Gas Mixtures Stored
in Tedlar Bags at Ambient Temperatures 25
7 Effect of Temperature on Chlorinated Hydrocarbon Concen-
tration of Gas Mixtures Stored in Tedlar Bags 26
8 "Memory" Effects in Tedlar Bags Resulting from High Concen-
trations of Chlorinated Hydrocarbons 27
9 Variation of C9H.C19 Concentration of a Gas Mixture in a
Double Tedlar Ba
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TABLES
Number Page
13 Kovats Retention Indices of Selected Compounds on
Porapak T, 80/100 Mesh in 6.5-Ft x 1/8-In Stainless
Steel at 140°C 33
14 Kovats Retention Indices of Selected Compounds on 15%
Tetracyanoethylated Pentaerythritol on 60/80 Mesh
Chromasorb P AW In 16-Ft x 1/8-In Stainless Steel. . . . 34-35
vn
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LIST OF ABBREVIATIONS AND SYMBOLS
ABBREVIATIONS
o
C - degree Celsius
EPA - U.S. Environmental Protection Agency
ft - foot
hr - hour
i.d. - inside diameter
in - inch
yl - microliter
ml - milliliter
min - minute
OAQPS - Office of Air Quality Planning and Standards
o.d. - outside diameter
ppm - part per million
SYMBOLS
CC1, - carbon tetrachloride
CoCl* - tetrachloroethylene
C2HC13 - trichloroethylene
C2H4C12 - ethylene dichloride
N« - nitrogen
vi i i
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ACKNOWLEDGMENTS
The authors wish to thank Mr. William Lonneman of this Agency for
permission to use his bag sealing machine. They also wish to thank
Mr. K. William Grimley and his colleagues in the Emission Measurement
Branch (ESED) for permission to include their Method for the Determination
of Halogenated Hydrocarbons from Stationary Sources in the Appendix of this
report.
IX
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SECTION 1
INTRODUCTION
Under the 1976 Toxic Substances Control Act, the U.S. Environmental Pro-
tection Agency (EPA) is given responsibility to test chemicals for health and
environmental effects. Recently, an interagency panel selected certain
categories of chemicals to be given high priority; the halogenated hydro-
carbons were designated as one such category (1). After screening many
halogenated hydrocarbons on the basis of degree of genotoxicity, production
volume, and potential for human exposure, a special task force prepared a
list of compounds for immediate attention (2). These compounds include
carbon tetrachloride (CCl^), ethylene dichloride (CgH^Clg), tetrachloro-
ethylene (C2C14), and trichloroethylene (CgHClj).
An essential feature in pollution assessment and control is develop-
ment of an accurate source test method to measure amounts of emissions and
to determine the efficacy of control technology. For this purpose, a Tenta-
tive Method was formulated in the Emission Measurement Branch, Emission
Standards and Engineering Division, Office of Air Quality Planning and
Standards (OAQPS) (see Appendix A). The present study was undertaken to
evaluate this method and to provide information to aid the user.
The test method under consideration involves collection in Tedlar bags
and analysis by gas chromatography with flame ionization detection. The use
of bottled gas mixtures is one calibration option. The ability of Tedlar
bags to preserve gas samples free from contamination and change has been
1
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the subject of many studies. Seila ejt al_. (3) reviewed recent work in this
area and studied the effects of simulated sunlight on stability of hydro-
carbon samples at ambient concentrations in Tedlar bags. They observed a
series of contamination peaks released by the radiation and suggested that
the origin of these peaks was manufacturing residues. In addition, Tedlar
bags also have been used for source sampling. In this field, samples usually
contain much higher concentrations, and the major problems result from
sample cross-contamination and from the extremes of temperature that are
encountered. Tedlar bags have been successfully employed in the source
sampling method for vinyl chloride (4). Further, a recent study in this
laboratory (5) dealt with the stability of benzene-containing gas mixtures
in Tedlar bags over a range of temperatures. It showed that benzene is quite
stable in Tedlar and relatively free from "memory" effects. The present
investigation was carried out to obtain information on the stability of gas
mixtures in Tedlar bags containing the four chlorinated hydrocarbons of
interest.
Cylinders of compressed gases are often used as secondary standards
during measurements in the field, where they are more convenient than
permeation tubes or diluted gas preparations. Therefore, this study also
examined the stability of compressed gases containing CCl^, CgH^Clg.
CgHCl-j, and CgCl^ in cylinders. The stability of these compounds under such
conditions has received only limited attention in the past (6). Further,
the present investigation included an evaluation of the gas chromatographic
column recommended in the Tentative Method for Analysis of Halogenated hydro-
carbons. Several other columns were also examined to provide analysts with
alternatives when interfering compounds are present.
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This work was carried out in the Source Section of the Quality Assurance
Branch, Environmental Monitoring and Support Laboratory, Research Triangle
Park, North Carolina, which has a program to evaluate and standardize source
emission test methodology. Work is continuing with other halogenated hydro-
carbons.
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SECTION 2
CONCLUSIONS
Steel cylinders containing CCK, CgFLCl^ CpHCK, and CgCl* in nitrogen
(N2) and aluminum cylinders containing C2HClg remain stable for 4 months when
maintained at ambient temperatures. After that time period, no concentration
changes are detected.
Tedlar bags may be used to contain mixtures of halogenated hydrocarbons
in N2 at source-level concentrations. When held at ambient temperatures,
CC14 remains stable for at least 10 days, C2C14 for 10 days, C2HC13 for 2
days, and CgH^Clg for 1 day.
Storage at -25°C in Tedlar bags for 16 hr does not cause changes in con-
centrations of any of the four halogenated hydrocarbons, provided that tem-
perature is maintained above the dew point.
When Tedlar bags containing the subject gas mixtures are heated to 70°C,
CC1*, CpHCUj and CpCK remain stable for 64, 8, and 5 hr, respectively.
Heating Tedlar bags containing C2H4C12 to 60°C causes the concentration to
decrease after only 1 hr. Therefore, steps should be taken to cool high-
temperature gas streams when sampling for CgH.CK and employing Tedlar bags.
The introduction of high concentrations of halogenated hydrocarbons
into Tedlar bags causes formation of persistent residues that may contaminate
subsequent samples. A decontamination procedure was employed that consisted
of flushing the bag with N2, heating to 60°C for 1 hr, and flushing again.
Bags contaminated with CC1, and C2C1^ can be decontaminated with one such
4
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treatment; C2HC13 requires two and C2H^C12 cannot be decontaminated by this
method.
At ambient temperatures C2H.C12 tends to be absorbed into the plastic;
at 60°C it permeates through the plastic.
The chromatographic column recommended in the Tentative Method for the
Analysis of Halogenated Hydrocarbons from Stationary Sources achieves
excellent separations with the four compounds of interest. Other columns
are also available for use under special circumstances.
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SECTION 3
EXPERIMENTAL
Tedlar bags were fabricated from 2-mil plastic sheets. The edges were
sealed with a Vertrod Thermal Impulse Heat Sealing Machine (Model 48 EPS 1/4
WC). Connections to the bag were made using an 0-Seal Straight Thread
Adapter with 0.25-in o.d. tube and a 7/16-20 thread (Swagelok 401-A-OR)
which was inserted through a 2-in-square piece of VisQueen polyethylene tape
fixed to the outside surface of the bag. The adapter was held in place with
a 0.058-in Teflon washer (0.5 in i.d. x 1-in o.d.) and a 7/16-20 nut.
A 7115G4B Hoke ball valve was connected to the adapter.
Cylinders containing gaseous mixtures of Ng and the chlorinated hydro-
carbons under investigation were obtained from Airco, Inc. (Research Triangle
Park, North Carolina). Hydrocarbon concentrations were determined using
Tedlar bag calibration standards by injection of the liquid compound while
filling the bags with Np. The N« was measured using a No. 802 Singer dry
gas meter; a No. 801, 10-ul Hamilton syringe was used to measure the compounds
of interest. In other instances, Tedlar bags were filled directly from the
reference cylinders.
Chlorinated hydrocarbon concentrations were determined using a Hewlett-
Packard Model 5830A gas chromatograph equipped with dual flame ionization
detectors and a 0.1-ml sampling loop. A Hewlett-Packard Model 18850A
integrating terminal was employed to record output. The chromatographic
column consisted of a 15-ft x 1/8 in stainless steel helix packed with 2Q%
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SP-2100/0.1% Carbowax 1500 on 100/200-mesh Supelcoport. The following
operating conditions were employed: inlet temperature, 250°C; column, 75°C;
detector, 300°C; carrier gas, liquid air Ng at 20 ml/min. Under these
conditions, only a single peak could be observed in each compound of interest.
Tedlar bags were sampled by drawing the gas through the chromatographic
sampling loop using the house vacuum. Bottled gases were forced through the
sampling system under their own pressures. A benzene gas mixture was used to
normalize the gas chromatograph results.
In several instances, gas samples containing high concentrations of the
subject compounds were introduced into Tedlar bags. These atmospheres were
prepared by slowly passing N2 gas through an impinger containing the liquid
compound under study. The concentration was calculated for the saturation
vapor pressure of the chlorinated hydrocarbon at 0°C, the temperature at
which the impinger was maintained. This temperature was chosen to assure
that condensation would not take place in the bag during the subsequent study.
To study the effusion of chlorinated hydrocarbons through Tedlar plastic,
a double bag assembly was constructed. This consisted of an inner bag housed
in an outer bag of approximately twice the volume, so that when the inner
bag was filled with a chlorinated hydrocarbon gas mixture, the outer bag could
be filled with an equivalent volume of pure Ng. This assembly was employed
in a previous study in this laboratory (5) and is illustrated in Figure 1.
Retention indices were determined for several chlorinated hydrocarbons
and a number of other selected compounds on five chromatographic columns.
The columns were:
Carbopak C-HT, 80/100 mesh in 6.5-ft x 1/8 in stainless steel.
10% FFAP on 80/100 mesh acid-washed Chromasorb W in 20-ft x 1/8 in
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stainless steel.
Porapak T, 80/100 mesh in 6.5-ft. x 1/8-in stainless steel.
20% SP-2100/0.1% Carbowax 1500 on 100/120 mesh Supelcoport in 15-ft x
1/8-in stainless steel.
15% tetracyanoethylated pentaerythritol on 60/80 mesh Chromasorb P
AW in 16-ft x 1/8-in stainless steel.
The columns were obtained from Supelco, Inc. (Belefonte, Pennsylvania)
and were conditioned overnight at a temperature and flow rate recommended by
the manufacturer. The compounds under investigation were used without further
purification.
Relative retentions in Kovats retention index units (7) were obtained
from chromatograms of suitable mixtures containing n-alkanes as internal
standards. Retention distances measured between point of injection and peak
maxima were corrected for the column gas holdup volume by means of retention
of methane (8). The adjusted retentions were then used to calculate values
for the retention index by means of the expression recommended by the Chroma-
tography Discussion Group (9):
logR - logR
I = 100 N + 100 n
lQ9RN+n '
where R , RN> and R.. are the adjusted retentions of the solute and n-alkanes
containing N and N+n carbon atoms, respectively.
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Fi.gure 1. Double Tedlar Bag Assembly,
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SECTION 4
RESULTS AND DISCUSSION
(STABILITY OF CHLORINATED HYDROCARBON GAS MIXTURES IN ALUMINUM AND STEEL
CYLINDERS)
Because cylinder gases were used as calibration standards for our Tedlar
bag studies, and also because of plans to use such cylinders in future quality
assurance programs, a study was undertaken to determine if gas mixtures con-
taining the chlorinated hydrocarbons under investigation remained stable in
bottled gas containers. A single steel cylinder each of CCl^, C^Clg, and
C2C1^, and two steel and two aluminum cylinders of CgHCU were employed. In
each case, the diluent gas was N2. The gases were measured at various intervals
over a period of approximately 4 months, counting time from the date of
cylinder preparation. The results are listed in Tables 1A and IB. A stability
test was carried out by performing a linear regression analysis on each data
set and calculating the time variation of the concentration. This latter
quantity was judged to be significant if its magnitude exceeded its standard
deviation by at least a factor of 3. The results of these analyses are listed
in Table 2. Since in each instance the calculated rate of change was not
measurably different from 0, the cylinder gases met the test for stability.
However, a concentration change was observed in the C2H4C12 cylinder and in
one C2HClo steel cylinder. The first point in each data set deviated con-
siderably from the subsequent values, indicating that the concentration under-
went a decrease immediately after the cylinder was prepared but then stabilized.
10
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TABLE 1A. TIME VARIATION OF CONCENTRATIONS OF CHLORINATED
HYDROCARBUNS IN CYLINDERS
Elapsed Time, Concentration,
days* ppm
CC14 CH2C1CH2C1 CC12:CC12 CHC1:CC12
(steel cylinder) (steel cylinder) (steel cylinder) (steel cylinder)
7
16
23
30
37
44
51
68
92
97
114
21.9
20.3
19.9
21.1
20.3
18.5
19.0
18.2
18.6
19.4
19.5
14.2
13.3
12.4
12.6
12.9
12.1
12.5
12.7
13.0
12.6
12.5
-
-
18.2
19.1
18.0
19.1
18.2
20.2
20.3
19.4
18.5
19.6
17.6
17.8
17.2
16.5
16.4
17.3
17.6
18.3
17.6
17.7
*From date of filling.
11
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TABLE IB. TIME VARIATION OF CONCENTRATIONS OF CHLORINATED
HYDROCARBONS IN CYLINDERS
Elapsed Time
days*
5
7
25
42
49
63
>
C2HC13
(steel cylinder)
9.7
9.6
9.9
10.1
9.7
9.5
Concentration
ppm
C2HC13
(aluminum cylinder)
30.0
27.9
31.4
29.4
29.1
28.8
»
C2HC13
(aluminum cylinder)
11.8
11.9
11.1
11.8
11.5
11.8
*From date of filling.
12
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TABLE 2. MEASURED RATES OF CONCENTRATION CHANGE OF CHLORINATED
HYDROCARBON CYLINDER GASES
Compound
cci4
C2H4C12
c2ci4
C2HC13 #1
C2HC13 #2
CUP1 J/O
pHLIo ffo
C2HC13 #4
Cylinder Concentration,
Type ppm
Steel
Steel
Steel
Steel
Steel
Al umi num
Aluminum
19.7
14.2
19.0
19.6
26.0
78.7
31.1
Rate of Change,* Standard
%/day Deviation
-0.06
-0.01
+0.05
+0.04
-0.02
-0.02
-0.02
0.04
0.03
0.05
0.03
0.05
0.08
0.05
The initial point was omitted in calculating the rate of change.
13
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Student's t-test was applied to the data to compare the deviations in
question with those that would occur with normal measurement fluctuations.
The t-test indicated a probability the deviations resulted from statistical
fluctuations of less than 0.01 and 0.025 for C2H4C12 and the CgHCU, respec-
tively. Thus, there was a correspondingly high probability that the points
under consideration were evidence for an initial decrease in concentration.
Because of this, both of these points were omitted when linear regression
analysis was applied to the data sets in question. The t-test was also
applied to the extreme point in each of the other data sets listed in Tables
1A and IB, with the result that all were within the range of normal measure-
ment fluctuations. Therefore, the data in Tables 1 and 2 are evidence that
the gases in the cylinders under study remained stable over a time period of
from 2 weeks to as long as 4 months after preparation.
Although stability was demonstrated at ambient temperatures, some
evidence was obtained that decay occurs at higher temperatures. One steel
and one aluminum cylinder containing CpHCU were remeasured and heated at
50°C in a Forma Scientific Environmental Chamber. At the end of 14 days,
they were brought to room temperature, and when remeasured, the steel and
aluminum cylinders measured 90.0±2.1 and 88.5±3.9% of the initial value,
respectively. The changes were significant at the 95% confidence level.
STABILITY OF CHLORINATED HYDROCARBON SAMPLES IN TEDLAR BAGS AT AMBIENT
TEMPERATURES
The stability of samples of C2HC13, C2C14> CCl^, and C2H4C12 in N2 stored
in Tedlar bags was studied. Several bag samples of each compound were pre-
pared by either filling the bags directly from standard cylinders or by in-
14
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jecting measured amounts of liquid into bags filled with known volumes of Ng.
The bags were measured daily over a period of time on a Hewlett-Packard 5830
gas chromatograph and concentrations were determined by comparison with
measurements of standard cylinders.
The results of the measurements (Tables 3 through 6) show that CC1* was
the most stable of the four compounds. The CC1, concentrations of two of the
three bags remained essentially unchanged for as long as 10 days. Calculations
by linear regression of the rate of decay yielded a value that was approxi-
mately equal to its standard deviation. The decay rate of the third bag was
measurable. The concentration in the third bag decreased by approximately 4%
per day; it contained a relatively high concentration of CC1., which may have
affected the decay rate.
C2C14 samples stored in Tedlar bags were also fairly stable. Although
the concentrations of two of the four bags decreased steadily over a 39-day
period, none decayed by more than 10% within 3 days.
Tedlar bag samples of C9HC1, were less stable. Of the four bags pre-
£ O
pared, two decayed steadily at an average rate of about 7% per day over an
11-day period. The concentrations of the other two bags were nearly constant
over a 14-day period.
CgH^Clg was the least stable of the four compounds. Two of the bags
decayed by approximately 5% in only 1 day. The third bag decayed by approxi-
mately 7% over the first 5 days.
The results of this study indicate the lengths of time that samples of
the four compounds can be stored in Tedlar bags without significant concen-
tration changes. If an approximate 10% decrease in concentration is con-
sidered tolerable, samples of C^Cl* can be stored for up 4 days; low concen-
15
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tration samples of CCl^ can be stored for 10 days or more. Samples of C2HC13
and CpH^Clp should be stored for no longer than 2 days and 1 day, respectively.
(STABILITY OF CHLORINATED HYDROCARBON SAMPLES IN TEDLAR BAGS AT TEMPERATURES
ABOVE AND BELOW AMBIENT)
Source sampling often must be carried out on heated gas streams or under
extreme weather conditions. For these reasons, some information also was
obtained about the stability of chlorinated hydrocarbon gas mixtures in
Tedlar bags at temperatures above and below ambient. In studying stability
at low temperatures, bag samples were stored in a freezer for a period of
16 hr. (In each case, the temperature remained above the dew point of the
compound under study.) The bags were then brought to room temperature and
measured.
The results (Table 7) show no observable change in the concentrations of
the compounds under study. When Tedlar bags were heated, however, some
changes were observed. Heating caused the release of some materials from the
plastic, but none eluted on the chromatogram at the same times as the com-
pounds of interest. Heating to 60°C caused one CgH^Clg gas sample to
decrease by 6.4% after 1 hr and another to decrease by 9.4%. On the other
hand, a CpCl, sample did not show a measurable change when heated to 60°C
for 1 hr, but heating to 70°C for 16 hr did cause a 26% decrease. After
heating a CgHCl^ sample to 90°C for 1 hr, a 5.3% change was observed. This
change was barely within the limit of detection. A 15% decrease was observed
at 75°C after 16 hr. In contrast, CCl^ gas samples were very stable at high
temperatures. After heating one sample repeatedly for a total of 63 hr at
70°C, only a 5% change could be detected.
16
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Certain conclusions can be drawn from these results. Gas samples con-
taining the four compounds of interest will not be affected if stored in
Tedlar bags at temperatures that are below ambient but above the compound's
dew point. Exposure of CgH^Clg bag samples to temperatures above 60°C should
be avoided, even for short periods of time. CpCl* and C^HCK samples may be
exposed to temperatures of approximately 70°C for a few hours without signi-
ficant losses. CC1* samples may be heated to 70°C for up to 63 hr without
undergoing important concentration changes.
MEMORY EFFECTS RESULTING FROM HIGH CONCENTRATIONS
"Memory" effects were studied by subjecting Tedlar bags to concentrations
of chlorinated hydrocarbons in the 5,000 to 40,000 ppm range. Such concen-
trations were employed because they result in correspondingly higher amounts
of residuals that are easier to detect. Although high concentrations should
not be expected in controlled effluent streams, they often occur as the result
of process upsets (4) and may contaminate a Tedlar bag that happens to be in
use. Therefore, it was necessary to obtain some information on the magnitude
of "memory" effects and to examine decontamination procedures.
To carry out this study, a high-concentration gas sample was prepared
for each compound of interest and introduced into a new Tedlar bag. After
1 hr, the bag was evacuated and flushed. The latter was accomplished by
filling the bag with gas and evacuating a total of three times. Each bag was
then filled N2 gas, checked to show that all of the chlorinated hydrocarbon
had been removed from the gas phase, and left to stand at room temperature
for 66 hr. The chlorinated hydrocarbon concentration in each bag was
subsequently measured. Following this, each bag was heated for 1 hr at 60°C
17
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and the concentration remeasured. The bag was then flushed and reheated as
described above and remeasured. The results are listed in Table 8.
.All of the bags that had contacted high concentrations of chlorinated
hydrocarbons retained some of these materials and released them into the gas
phase when left to stand at room temperature (see Table 8). Upon heating, an
additional amount of material was released. In the case of CgHClo and CpH^Clp,
amounts of this were large. When the bags were reflushed and reheated, those
that had contained CgHClg and C2H4C12 continued to release material, but
those that had contained CCl^ and C2C14 released only negligible amounts.
The results of this study of high concentrations of chlorinated hydro-
carbons may be summarized as follows. Tedlar bags that contact high concen-
trations retain material even after the sample is removed and the bag is
thoroughly flushed. Such residuals can contaminate subsequent samples.
Heating to 60°C and flushing with N2 is sufficient to remove contamination
from Tedlar bags that have been filled with 42,000 ppm CC14 and 5,700 ppm
C2C14. On the other hand, Tedlar bags filled with 27,000 ppm CgHClg require
two such treatments, and 30,000 ppm C^HClp cannot be decontaminated by this
procedure. These results also show that the order of degree of absorption
into Tedlar plastic is C2H4C12 > C2HC13 > C2C14 > CC14, and is the same as
the order found for rates of decay of gaseous samples. Therefore, the results
obtained for the absorption of chlorinated hydrocarbons into Tedlar are
consistent with our findings about sample decay.
C2H4C12 GAS MIXTURE IN A DOUBLE TEDLAR BAG
In order to obtain some additional information about the loss of
chlorinated hydrocarbons from Tedlar bags, a double bag was employed. This
technique is described in Section 3. A mixture of C2H4C12 in N2 was placed
18
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in the inner bag and an approximately equal volume of N2 gas was placed in
the outer bag. The CpH^Cl^ concentrations in both bags were observed over a
7-day interval. The assembly was then heated to 60°C for 22 hr and the con-
centration measured over an additional 8 days. The results are shown in
Table 9.
Prior to heating, the CgH^C^ concentration in the inner bag decreased
but no C2H.C12 was detected in the outer bag. Heating caused a further
decrease in the inner bag concentration and caused CpH.Clp to appear in the
outer bag. In the subsequent time interval, the C2H*C12 concentration
decreased in both bags. These findings are evidence that the concentration
decrease is the result of absorption into the plastic and not effusion through
the bag. Heating apparently increases mobility through the plastic and results
in the expulsion of some C,,H4C12 from the plastic. This viewpoint is con-
sistent with the fact that contamination can be removed from the bags by
heating.
When the data in Table 9 were subjected to kinetic analysis, the first-
order rate constants for the changes in the inner bag before and after heating
were -0.012 ± 0.001 d"1 and -0.011 ± 0.003 d , respectively. (The variations
are standard deviations.) On the other hand, the corresponding constant for
the decay of C2H4C12 in the outer bag was determined to be -0.037 ± 0.009 d ,
a difference in magnitude that is statistically significant. It may be
assumed, then, that the gas in the outer bag has a greater rate of decay
because it is in contact with a greater surface area. Thus, these results
are also consistent with the supposition that C2H^C12 is absorbed into the
Tedlar plastic.
19
-------
SEPARATION OF HALOGENATED HYDROCARBONS BY GAS CHROMATOGRAPHY
The separation of the chlorinated compounds of interest from other sub-
stances by gas chromatography was also investigated. The column specified
in the Tentative Method for Halogenated Hydrocarbons was studied, along with
four others. Relative retentions in Kovats retention index units (7) were
determined from the elution times of compounds in suitable mixtures. These
calculations are described in Section 3 above; the results are listed in
Tables 9 through 13. Tables of retention indices are often used as a guide
in selecting chromatographic columns for separating complex mixtures and for
making preliminary identifications of components. As a general rule, it is
best to have differences of 30 retention units between compounds in order to
obtain interference-free measurements.
The column specified in the Tentative Method employs methyl silicone
(SP-2100) in the stationary phase. The column separates the four compounds
of interest from each other and from many other chlorine-containing com-
pounds (see Table 9). The data also show that there are other potential
interferents. However, our present concern is for the use of this column to
measure emissions from dry cleaning and metal degreasing operations in which
many such interfering compounds would not ordinarily be present. An example
of an unlikely interferent is furfural, which has the same retention index as
CpCl* on the column under discussion. On the other hand, it should be noted
that the retention indices of CpH-CU. CC1*, and C^HCU fall between 600 and
700, a region in which many gasoline hydrocarbons elute.
Table 11 presents the results obtained using Carbopak C-HT. Carbopak
C-HT is a graphitized thermal carbon black that has been treated with hydrogen
at 1000°C (10). It is said to have a high resolving power. On this column,
20
-------
the chlorinated hydrocarbons of interest are well separated and elute with
the lighter hydrocarbons. The latter process would be an advantage in
resolving the compounds of interest from gasoline hydrocarbons.
The FFAP column is one that has been employed by the National Institute
of Occupational Safety and Health for the analysis of organic solvents in
air (11). The stationary phase consists of free fatty acid Carbowax 20 M
reacted with nitroterephthalic acid. The results (Table 12) show that
chlorinated hydrocarbons elute over a wide range of indices. Many of the
compounds of interest elute after the gasoline hydrocarbons. CHClg and
CgCl^ are not well separated.
Porapak T is a porous polymer based on ethyleneglycoldimethacrylate and
is reported to possess fair resolving power (10). On this column, many
chlorinated hydrocarbons are well separated, except that C^H^Cl^ and CpHCU
interfere (see Table 13).
The final column employs tetracyanoethy1ated pentaerythrltol as a
stationary phase. It is a highly polar column, and many compounds have
retention indices that vary considerably with temperature; others show less
variation (see Table 14). With such columns, it is often possible to
resolve interfering substances by changing column temperature.
21
-------
TABLE 3. VARIATION OF CC14 CONCENTRATION OF GAS MIXTURE
STORED IN TEDLAR BAGS AT AMBIENT TEMPERATURES
Elapsed Time,
days*
0
1
2
3
4
5
6
7
8
9
10
Bag 1
9.24
9.52
9.55
9.28
8.96
9.23
9.21
9.27
9.11
CC1. Concentration,
ppm
Bag 2
1034
999
948
936
838
849
688
Bag 3
28.8
28.9
28.0
28.0
*From date when bags were prepared.
22
-------
TABLE 4. VARIATION OF C2C14 CONCENTRATION OF GAS MIXTURES
STORED IN TEDLAR BAGS AT AMBIENT TEMPERATURES
Elapsed Time,
days*
0
1
2
3
4
5
6
7
25
35
36
38
39
Bag 1
19.7
17.9
16.8
15.9
15.5
14.6
4.2
2.5
2.2
c2c
Bag 2
10.9
»
10.0
9.4
9.2
9.2
8.8
4.3
3.9
3.8
\» Concentration,
ppm
Bag 3
65.0
63.5
62.2
61.6
59.2
60.2
58.2
Bag 4
32.1
31.7
31.0
30.9
29.6
30.1
29.1
*From date when bags were prepared.
23
-------
TABLE 5. VARIATION.OF C2HC13 CONCENTRATION OF GAS MIXTURES
STORED IN TEDLAR BAGS AT AMBIENT TEMPERATURES
Elapsed Time,
days*
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
"2
Bag 1 Bag 2
21.3 65.1
20.0 60.9
19.7 51.0
19.9 48.0
19.7 41.2
20.0 30.2
20.4 12.1
20.0 0.3
20.0
20.1
19.7
HC13 Concentration,
ppm
Bag 3
16.0
15.0
14.4
15.0
14.4
15.0
15.2
15.0
15.0
15.0
14.7
Bag 4
7.0
6.6
6.9
6.0
5.5
4.3
3.7
3.1
2.3
1.1
*From date when bag was prepared.
24
-------
TABLE 6. VARIATION OF C2H4C12 CONCENTRATION OF GAS MIXTURES
STORED IN TEDLAR BAGS AT AMBIENT TEMPERATURES
Elapsed Time,
days*
Bag 1
C2H,C12 Concentration,
ppm
Bag 2 Bag 3
0 31.8
1 29.9
2 28.6
5
6 22.1
7
8 19.2
9 16.6
11
12
16
6.2 91.9
5.9
5.5
86.0
83.4
5.3 81.8
80.5
4.9
80.1
78.2
*From date when bags were prepared.
25
-------
TABLE 7. EFFECT OF TEMPERATURE ON CHLORINATED HYDROCARBON
CONCENTRATION OF GAS MIXTURES STORED IN TEDLAR BAGS
Compound
cci4
cci4
cci4
cci4
cci4
cci4
C2H4C12
C2H4C12
C2H4C12
C2H4C12
c2ci4
c2ci4
c2ci4
C2HC13
C2HC13
C2HC13
C2HC13
Sample
Number
1
2
2
2
2
2
1
2
3
4
1
2
2
1
2
2
3
Temperature,
°C
-25
75
70
70
70
70
-41
60
60
60
-25
60
70
90
-25
75
-25
Time,
hr
16
1
16
6
16
24
16
1
1
2
16
1
16
1
16
16
16
Concentration,
ppm
Initial
18.7
46.6
46.6
46.6
46.6
46.6
7.35
7.35
7.35
7.35
21.4
20.4
20.4
21.4
21.3
21.3
12.9
Final
19.3
46.1
47.2
45.4
44.8
44.2
7.39
7.25
6.88
6.66
21.1
20.6
15.1
20.2
21.8
18.1
13.3
Change,
103.2
98.9
101.3
97.4
96.0
94.7
100.5
98.6
93.6
90.6
98.8
100.5
74.0
94.7
102.3
85.0
103.1
26
-------
TABLE 8. "MEMORY" EFFECTS IN TEDLAR BAGS RESULTING FROM
HIGH CONCENTRATIONS OF CHLORINATED HYDROCARBONS
Compound
cci4
c2ci4
C2HC13
C2H4C12
Initial*
42,000
5,700
27,500
30,100
After
Flushing
8.5
12.5
14.4
8.9
Concentration,
ppm
After
Heating
10.7
14.4
65.9
185.0
After
Second Heating**
0.0
0.2
1.4
5.4
Calculated from vapor pressure at 0°C.
**Bag flushed before second heating.
27
-------
TABLE 9. VARIATION OF C2H4C12 CONCENTRATION OF A GAS
MIXTURE IN A DOUBLE TEDLAR BAG
Elapsed Time,
days*
0
5
7
8
9
12
16
Inner bag
91.0
86.1
83.6
75.5
73.4
70.0
69.0
CgH^Clg Concentration,
ppm
Outer bag
0.0
0.0
0.0
6.2+
5.7
4.8
4.6
*From date when bag was prepared.
+After heating at 60°C for 22 hr.
28
-------
TABLE 10. KOVATS RETENTION INDICES OF SELECTED COMPOUNDS
ON 20% SP-2100/0.1% CARBOWAX 1500 on 100/200 MESH SUPELCOPORT IN
15-FT X 1/8-IN STAINLESS STEEL AT 70°C
Chlorinated Compound Index
dichloromethane 516
trans-1,2-dichloroethene 556
1,1-di chloroethane 565
chloroform 606
ethylene dichloride 636
1-chlorobutane 641
carbon tetrachloride 665
trichloroethylene 695
1-chloropentane 746
2-chloropentane 746
1,3-dichloropropane 765
tetrachloroethylene 813
chlorobenzene 842
1,4-dichlorobutane 886
1,2,3-trichloropropane 898
p-chlorotoluene 948
Other Compound Index
methanol 370
acetaldehyde 374
methyl formate 392
2-propanol 477
diethyl ether 488
methylal 493
formaldehyde 508
ethyl bromide 514
cyclopentene 560
4-methylpentene-l 562
cyclopentane 567
4-methylpentene-2 569
2-methylpentene-l 574
methyl ethylketone 579
hexene-1 590
methyl aerylate 595
29
-------
TABLE 10. KOVATS RETENTION INDICES OF SELECTED COMPOUNDS
ON 20% SP-2100/0.1% CARBOWAX 1500 on 100/200 MESH SUPELCOPORT IN
15-FT X 1/8-IN STAINLESS STEEL AT 70°C (Continued)
Other Compound
hexane
2-ethylbutene-l
2,2-dimethylpentane
crotonaldehyde
methylcyclopentane
1-butanol
methylcyclopentene
benzene
3,3-dimethylpentane
thiophene
cyclohexane
2-pentanone
2,3-dimethylpentane
3-pentanone
cyclohexene
heptene-1
heptane
1,4-dioxane
methyli sobutylketone
methylcyclohexane
pyridine
toluene
methylcyclopentene
butyl acetate
octane
furfural
amyl acetate
ethyl benzene
m-xylene
p-xylene
nonane
o-xylene
decane
naphthalene
Index
600*
600
621
629
633
649
654
658
660
663
667
668
672
677
683
689
700*
721
722
728
733
761
770
795
800*
813
860
869
876
877
900*
900
1000*
1182
*Used as a standard.
30
-------
TABLE 11. KOVATS RETENTION INDICES OF SELECTED COMPOUNDS ON
CARBOPAK C-HT. 80/100 MESH IN 6.5-FT X 1/8-IN STAINLESS STEEL
AT 90°C
Chlorinated Compound
1 ,1-dichloroethane
chloroform
trans-1 ,2-dichloroethylene
ethyl ene di chloride
carbon tetrachloride
1-chlorobutane
trichloroethylene
1,1,1 -tr i chl oroethane
tetrachl oroethyl ene
Other Compound
methyl alcohol
methyl formate
acetone
propanol
2-propanol
butane
furan
ethyl formate
methyl al
butanal
methyl ethyl ketone
pentane
cyclopentanone
cyclohexane
thiophene
methyl aery late
diacetyl
cyclohexanone
benzene
3-pentanone
2-pentanone
toluene
isooctane
pyridine
ethyl benzene
1 -hexene
butyl acetate
hexane
Index
427
443
454
460
502
532
546
568
574
Index
331
340
380
387
396
400*
407
418
432
473
476
500*
509
511
512
519
534
536
557
558
564
568
570
572
573
577
578
600*
*Used as a standard.
31
-------
TABLE 12. KOVATS RETENTION INDICES OF SELECTED COMPOUNDS ON 10% FFAP ON
80/100 MESH ACID-WASHED CHROMASORB W IN 20-FT X 1/8 IN STAINLESS STEEL AT 125°C
Chlorinated Compound Index
1,1-dichloroethylene 738
benzyl chloride 770
2-chlorobutane 800
1-chlorobutane 855
trans-l,2-dichloroethylene 864
2-chloropentane 886
carbon tetrachloride 893
1,1-dichloroethane 896
1,1,1-trichloroethane 897
methylene dichloride 934
trichloroethylene 1004
chloroform 1025
tetrachloroethylene 1039
1-chlorohexane 1054
ethylene dichloride 1078
Other Compound Index
heptane
3-heptene
1-heptene
octane
methyl acetate
1 -octene
2-ethyl, 1-hexene
nonane*
ethyl acetate
methacrolein
methyl propanoate
methyl ethyl ketone
1 -nonene
benzene
propyl acetate
decane
methyl butanoate
1 -decene
ethyl butanoate
toluene
dioxane
undecane
700*
744
746
800*
844
845
846
900
901
904
92T
927
945
963
988
1000*
1000
1044
1048
1060
1093
1100*
*Used as a standard.
32
-------
TABLE 13. KOVATS RETENTION INDICES OF SELECTED COMPOUNDS ON PORAPAK T,
80/100 MESH IN 6.5-FT X 1/8-IN STAINLESS STEEL AT 140°C
Chlorinated Compound Index
trans-1,2-dichloroethylene 550
carbon tetrachloride 553
1,1-di chloroethane 604
chloroform 625
n-butyl chloride 654
trichloroethylene 665
ethylene dichloride 666
tetrachloroethylene 736
Other Compound Index
methanol 426
methyl formate 465
pentane 500*
furan 510
propanol 533
methylal 547
ethyl formate 561
isopropyl alcohol 576
4-methyl-2-pentene 582
4-methyl-1-pentene 584
hexane 600*
1-hexene 603
2-ethyl-l-butene 603
2-hexene 605
tetrahydrofuran 609
isooctane 618
cyclohexane 619
butanal 634
acetone 636
2-butanone 639
methyl ethylketone 644
ethyl acetate 646
benzene 658
thiophene 658
diacetyl 667
heptane 700*
*Used as a standard.
33
-------
TABLE 14. KOVATS RETENTION INDICES OF SELECTED COMPOUNDS ON 15%
TETRACYANOETHYLATED PENTAERYTHRITOL ON 60/80 MESH CHROMASORB P AW IN
16-FT X 1/8-IN STAINLESS STEEL
Chlorinated Compound Index
at 80°C at 100°C
1,1-dichloroethylene 760 792
carbon tetrachloride 897 938
1,1-dichloroethane 940 994
methylene dichloride 956 1013
trichloroethylene 1009 1068
chloroform 1022 1090
tetrachloroethylene 1056 1105
1-chlorobutane 1105
1-chlorohexane 1148 1148
1,2-dichloroethane 1131 1205
1,4-dichlorobutane 1303
chlorobenzene 1347
1,3-dichloropropane 1352
Other Compound at 80°C at 100°C
isooctane
heptane
nonane
1 -nonene
ethyl formate
2-propanol
1-decene
ethyl acetate
acetone
undecane
benzene
methyl acrylate
2-methoxy ethanol
methyl ethyl ketone
pyridine
propyl butanoate
thiophene
dodecane
toluene
monoethanol ami ne
crotonaldehyde
ethyl benzene
m-xylene
700*
900*
1047
1009
1100*
1039
1087
1132
1143
1102
1200*
1136
683
700*
900*
972
1014
1046
1070
1076
1091
1100*
1104
1125
1155
1158
1158
1170
1176
1200*
1201
1268
1275
1281
1297
*Used as a standard.
34
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TABLE 14. KOVATS RETENTION INDICES OF SELECTED COMPOUNDS ON 15%
TETRACYANOETHYLATED PENTAERYTHRITOL ON 60/80 MESH CHROMASORB P AW IN
16-FT X 1/8-IN STAINLESS STEEL (Continued)
Other Compound
p-xylene
cumene
o-xylene
tetradecane
styrene
Index
at 80°C
at 100°C
1312
1318
1353
1400*
1419
*Used as a standard.
35
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REFERENCES
1. Regulators Release Chemicals Hit List. Chemical and Engineering News,
56:19, December 11, 1978.
2. Bachmann, J. D. (Pollutant Strategies Branch). Prioritization and
Assessment of High-Volume Industrial Organic Chemicals. Memorandum to
J.R. O'Connor, Chief, Pollutant Strategies Branch, Strategies and Air
Standards Division, Office of Air Quality Planning and Standards,
U.S. Environmental Protection Agency, Research Triangle Park,
North Carolina, December 28, 1977.
3. Seila, R. L., W. A. Lonneman, and S. A. Meeks. Evaluation of Polyvinyl
Fluoride as a Container Material for Air Pollution Samples. J. Environ-
mental Science, A-ll .-121-130, 1976.
4. Scheil, G. W. Standardization of Stationary Source Method for Vinyl
Chloride. Environmental Monitoring Series EPA-600/4-77-026, U.S. En-
vironmental Protection Agency, Research Triangle Park, North Carolina,
May 1977.
5. Knoll, J. E., W. H. Penney, and M. R. Midgett. The Use of Tedlar Bags
to Contain Gaseous Benzene Samples at Source Level Concentrations.
Environmental Monitoring Series EPA-600/4-78-057, U.S. Environmental
Protection Agency, Research Triangle Park, North Carolina, November 1978.
6. Cadoff, E. C., E. E. Hughes, R. Alvarez, and J. K. Taylor. Preparation
of Charcoal Sampling Tubes Containing Known Quantities of Adsorbed
Solvents. NBS Report NBSIR-74-530, National Bureau of Standards,
36
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Department of Commerce, Washington, D.C., 1974.
7. Kovats, E. Gas-chromatographische Charakterisierung organischer Verbind-
ungen Teil 1:Retentionsindices aliphatischer Halogenide, Alkohole,
Aldehyde und Ketone. Helv. Chim. Acta, 41:1915, 1958.
8. Feinland, R., A. 0. Andreatch, and D. P. Cotrup. Gas Chromatographic
Calculations. Anal. Chem., 33:991, 1961.
9. Data Sub-Committee of the Gas Chromatography Discussion Group, Gas
Chromatography, 1964, A. Goldup, ed. Institute of Petroleum, London,
1965, p. 303.
10. Vidal-Madjar, C., M. F. Gonnord, F. Benchah, and G. Guichon. Perform-
ance of Various Adsorbents for the Trapping and Analysis of Organohalo-
genated Air Pollutants by Gas Chromatography. J. Chromat. Sci., 16:190-
196, 1978.
11. White, L. D., D. G. Taylor, P. A. Mauer, and R. E. Kupel. A Convenient
Optimized Method for the Analysis of Selected Solvent Vapors in the
Industrial Atmosphere. Amer. Ind. Hyg. Assoc. J., 31:225, 1970.
37
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APPENDIX A
METHOD FOR THE DETERMINATION OF HALOGENATED ORGANICS FROM
STATIONARY SOURCES
38
-------
METHOD 23. DETERMINATION OF HALOGENATED
ORGANICS FROM STATIONARY SOURCES
INTRODUCTION
Performance of this method should not be attempted
by persons unfamiliar with the operation of a gas
chromatograph9 nor by those who are unfamiliar with
source samplings as there are many details that are
beyond the scope of this presentation. Care must
be exercised to prevent exposure of sampling personnel
to hazardous emissions-
1. Principle and Applicability
1.1 Principle. An integrated bag sample of stack gas containing
one or more halogenated organics is subjected to gas chromatographic
(GC) analysis, using a flame ionization detector (FID).
1.2 Applicability. The method is applicable to the measurement of
halogenated organics such as carbon tetrachloride, ethylene dichloride9
perchloroethylene9 trichloroethylene, methyl ene chloride, 1-1-1 tri-
chloroethane, and trichlorotrifluoroethane in stack gases only from
specified processes. It is not applicable where the gases are contained
in particulate matter.
2. Range and Sensitivity
The procedure described herein is applicable to the measurement of
halogenated organics in the 0.1 to 200 ppm range. The upper limit may
be extended by further calibration or by dilution of the sample.
3. Interferences
The chromatograph column with the corresponding operating parameters
herein described has been represented as being useful for producing
adequate resolution of halogenated organics. However, resolution
39
-------
interferences may be encountered on some sources. Also, the chrom-
atograph operator may know of a column that will produce a superior
resolution of the particular compound of interest without reducing the
response to that compound, as specified in Section 4.3.1.
In any event, the chromatograph operator shall select a column
which is best suited to his particular analysis problem, subject to the
approval of the Administrator. Such approval shall be considered
automatic provided that confirming data produced through a demonstrably
adequate supplemental analytical technique, such as analysis with a
different column or G.C./mass spectroscopy, is available for review by
the Administrator.
4. Apparatus
4.1 Sampling (see Figure 23-1).
4.1.1 Probe. Stainless steel, Pyrex glass, or Teflon tubing
according to stack temperature, each equipped with a glass wool plug to
remove particulate matter if particulate matter is present.
4.1.2 Sample Line. Teflon, 6.4 mm outside diameter, of sufficient
length to connect probe to bag. A new unused piece is employed for each
series of bag samples that constitutes an emission test.
4.1.3 Male (2) and female (2) stainless steel quick connects, with
ball checks (one pair without) located as shown in Figure 23-1.
4.1.4 Tedlar or aluminized Mylar bags, 100 liter capacity. To
contain sample.
4.1.5 Rigid leakproof containers for 4.1.4, with covering to
protect contents from sunlight.
Mention of trade names or specific products does not constitute
endorsement by the Environmental Protection Agency.
40
-------
4.1.6 Needle Valve. To adjust sample flow rate.
4.1.7 Pump—Leak-Free. Minimum capacity 2 liters per minute.
4.1.8 Charcoal Tube. To prevent admission of halogenated organics
to the atmosphere in the vicinity of samplers.
4.1.9 Flow Meter. For observing sample flow rate; capable of
measuring a flow range from 0.10 to 1.00 liters per minute.
4.1.10 Connecting Tubing. Teflon, 6.4 mm outside diameter, to
assemble sample train (Figure 23-1).
4.2 Sample Recovery.
4.2.1 Tubing. Teflon, 6.4 mm outside diameter, to connect bag to
gas chromatograph sample loop. A new unused piece is employed for each
series of bag samples that constitutes an emission test, and is to be
discarded upon conclusion of analysis of those bags.
4.3 Analysis.
4.3.1 Gas Chromatograph. With FID, potentiometric strip chart
recorder and 1.0 to 2.0 ml sampling loop in automatic sample valve. The
chromatographic system shall be capable of producing a response to 0.1
ppm of the halogenated organic compound that is at least as great as the
average noise level. (Response is measured from the average value of
the baseline to the maximum of the waveform, while standard operating
conditions are in use.)
4.3.2 Chromatographic Column. Stainless steel, 3.05 m x 3.2 mm,
containing 20 percent SP-2100/0.1 percent Carbowax 1500 on 100/120
Supelcoport. Other columns can be used, provided that the precision
and accuracy of the analysis of standards are not impaired. Information
confirming that adequate resolution of the halogenated organic compound
41
-------
peak is accomplished should be available. Adequate resolution is
defined as an area overlap of not more than 10 percent of the halo-
genated organic compound peak by an interferent peak. Calculation
of area overlap is explained in Appendix E, Supplement A: "Determi-
nation of Adequate Chromotographic Peak Resolution."
4.3.3 Flow Meters (2). Rotameter type, 0 to 100 ml/min
capacity.
4.3.4 Gas Regulators. For required gas cylinders.
4.3.5 Thermometer. Accurate to one degree centigrade, to measure
temperature of heated sample loop at time of sample injection.
4.3.6 Barometer. Accurate to 5 mm Hg, to measure atmospheric
pressure around gas chromatograph during sample analysis.
4.3.7 Pump—Leak-free. Minimum capacity 100 ml/min.
4.3.8 Recorder. Strip chart type, optionally equipped with disc
integrator or electronic integrator.
4.3.9 Planimeter. Optional, in place of disc or electronic
integrator, for 4.3.8 to measure chromatograph peak areas.
4.4 Calibration. 4.4.2 through 4.4.6 are for section 7.1 which
is optional.
4.4.1 Tubing. Teflon, 6.4 mm outside diameter, separate pieces
marked for each calibration concentration.
4.4.2 Tedlar or Aluminized Mylar Bags. 50-liter capacity, with
valve; separate bag marked for each calibration concentration.
4.4.3 Syringe. 25 yl, gas tight, individually calibrated, to
dispense liquid halogenated organic solvent.
42
-------
4.4.4 Syringe. 50 yl, gas tight, individually calibrated, to
dispense liquid halogenated organic solvent.
4.4.5 Dry Gas Meter, With Temperature and Pressure Gauges.
Accurate to +2 percent, to meter nitrogen in preparation of standard gas
mixtures, calibrated at the flowrate used to prepare standards.
4.4.6 Midget Impinger/Hot Plate Assembly. To vaporize solvent.
5. Reagents
It is necessary that all reagents be of chromatographic grade.
5.1 Analysis.
5.1.1 Helium Gas or Nitrogen Gas. Zero grade, for chromatographic
carrier gas.
5.1.2 Hydrogen Gas. Zero grade.
5.1.3 Oxygen Gas or Air as Required by the Detector. Zero grade.
5.2 Calibration. Use one of the following options: either 5.2.1
and 5.2.2, or 5.2.3.
5.2.1 Halogenated organic compound, 99 mol percent pure, certified
by the manufacturer to contain a minimum of 99 mol percent of the
particular halogenated organic compound; for use in the preparation of
standard gas mixtures as described in Section 7.1.
5.2.2 Nitrogen Gas. Zero grade, for preparation of standard gas
mixtures as described in Section 7.1.
5.2.3 Cylinder Standards (3). Gas mixture standards (200, 100,
and 50 ppm of the halogenated organic compound of interest, in nitrogen)
for which the gas composition has been certified with an accuracy of +3
percent or better by the manufacturer. The manufacturer must have
recommended a maximum shelf life for each cylinder so that the concentration
43
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does not change by greater than +_ 5 percent from the certified value.
The date of gas cylinder preparation, certified concentration of the
halogenated organic compound and recommended maximum shelf life must
have been affixed to the cylinder before shipment from the gas manu-
facturer to the buyer. These gas mixture standards may be directly used
to prepare a chromatograph calibration curve as described in Section 7.2.2.
5.2.3.1 Cylinder Standards Certification. The concentration of
the halogenated organic compound in nitrogen in each cylinder must have
been certified by the manufacturer by a direct analysis of each cylinder
using an analytical procedure that the manufacturer had calibrated on
the day of cylinder analysis. The calibration of the analytical pro-
cedure shall, as a minimum, have utilized a three-point calibration
curve. It is recommended that the manufacturer maintain two calibration
standards and use these standards in the following way: (1) a high
concentration standard (between 200 and 400 ppm) for preparation of a
calibration curve by an appropriate dilution technique; (2) a low con-
centration standard (between 50 and 100 ppm) for verification of the
dilution technique used. If the difference between the apparent
concentration read from the calibration curve and the true concentration
assigned to the low concentration standard exceeds 5 percent of the true
concentration, determine the source of error and correct it, then repeat
the three-point calibration.
5.2.3.2 Establishment and Verification of Calibration Standards.
The concentration of each calibration standard must have been established
by the manufacturer using reliable procedures. Additionally, each
calibration standard must have been verified by the manufacturer by
44
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one of the following procedures, and the agreement between the initially
determined concentration value and the verification concentration value
must be within +_ 5 percent: (1) verification value determined by
comparison with a gas mixture prepared in accordance with the procedure
described in Section 7.1.1 and using 99 mol percent of the halogenated
organic compounds, or (2) verification value obtained by having the
calibration standard analyzed by the National Bureau of Standards, if
such analysis is available. All calibration standards must be reverified
on a time interval consistent with the shelf life of the cylinder
standards sold.
5.2.4 Audit Cylinder Standards (2). Gas mixture standards identi-
cal in preparation to those in Section 5.2.3 (the halogenated organic
compounds of interest, in nitrogen), except the concentrations are only
known to the person supervising the analysis of samples. The concentrations
of the audit cylinders should be: one low concentration cylinder in the
range of 25 to 50 ppm, and one high concentration cylinder in the range
of 200 to 300 ppm. When available, audit cylinders may be obtained by
contacting: EPA, Environmental Monitoring and Support Laboratory,
Quality Assurance Branch (MD-77), Research Triangle Park, North Carolina
27711. If audit cylinders are not available at EPA, an alternate source
must be secured.
6. Procedure
6.1 Sampling. Assemble the sample train as in Figure 23-1.
Perform a bag leak check according to Section 7.3.2. Join the quick
connects as illustrated, and determine that all connections between the
bag and the probe are tight. Place the end of the probe at the
45
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centroid of the stack and start the pump with the needle valve adjusted
to yield a flow of 0.5 1pm. After a period of time sufficient to purge
the line several times has elapsed, connect the vacuum line to the bag
and evacuate the bag until the rotameter indicates no flow. At all
times, direct the gas exiting the rotameter away from sampling personnel.
Then reposition the sample and vacuum lines and begin the actual sampling,
keeping the rate constant. At the end of the sample period, shut off
the pump, disconnect the sample line from the bag, and disconnect the
vacuum line from the bag container. Protect the bag container from
sunlight.
6.2 Sample Storage. Sample bags must be kept out of direct sun-
light and must be protected from heat. Analysis must be performed
within 1 day of sample collection for methylene chloride, ethylene
dichloride and trichlorotrifluoroethane. Analysis of perchloroethylene,
trichloroehtylene, 1,1, 1-trichloroethane and carbon tetrachloride must
be performed within 2 days.
6.3 Sample Recovery. With a new piece of Teflon tubing identified
for that bag, connect a bag inlet valve to the gas chromatograph sample
valve. Switch the valve to receive gas from the bag through the sample
loop. Arrange the equipment so the sample gas passes from the sample
valve to a 0-100 ml/min rotameter with flow control valve followed by a
charcoal tube and a 0-1 inch w.g. pressure gauge. Sample flow may be
maintained either by a vacuum pump or container pressurization if the
collection bag remains in the rigid container. After sample loop
purging is ceased, allow the pressure gauge to return to zero before
activating the gas sampling valve.
46
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TRAIN FOR PREPARATION OF SAMPLES
NITROGEN CYLINDER
HOT PLATE
TEDLAR BAG
CAPACITY
47
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INTEGRATED - BAG SAMPLING TRAIN
FILTER (GLASS WOOL)
PROBE
TEFLON
.SAMPLE LINE
VACUUM LINE
QUICK
CONNECTS
(MALE)
-N
NO BALL
CHECKS
QUICK
CONNECTS
(FEMALE)
TEDLAROR
ALUMINIZED
MYLAR BAG
RIGID LEAK-PROOF
CONTAINER
CHARCOAL TUBE
FLOW METER
PUMP
48
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6.4 Analysis. Set the column temperature to 100° C, and the
detector temperature to 225° C. When optimum hydrogen and oxygen flow
rates have been determined, verify and maintain these flow rates during
all chromatograph operations. Using zero helium or nitrogen as the
carrier gas, establish a flow rate in the range consistent with the
manufacturer's requirements for satisfactory detector operation. A
flow rate of approximately 20 ml/min should produce adequate separations.
Observe the base line periodically and determine that the noise level
has stabilized and that base line drift has ceased. Purge the sample
loop for thirty seconds at the rate of 100 ml/min, then activate the
sample valve. Record the injection time (the position of the pen on
the chart at the time of sample injection), the sample number, the
sample loop temperature, the column temperature, carrier gas flow
rate, chart speed and the attenuator setting. Record the laboratory
pressure. From the chart, note the peak having the retention time
corresponding to the halogenated organic compound as determined in
Section 7.2.1. Measure the halogenated organic compound peak area,
A , by use of a disc integrator, electronic integrator, or a plani-
meter. Record A and the retention time. Repeat the injection at
least two times or until two consecutive values for the total area of
the peak do not vary more than 5 percent. The average value for these
two total areas will be used to compute the bag concentration.
6.5 Measure the ambient temperature and barometric pressure near
the bag. From a water saturation vapor pressure table, determine and
record the water vapor content of the bag as a decimal figure. (Assume
the relative humidity to be 100 percent unless a lesser value is known.)
49
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7. Standards, Calibration, and Quality Assurance
7.1 Standards.
7.1.1 Preparation of Standard Gas Mixtures. (Optional-delete if
cylinder standards are used.) Assemble the apparatus shown in Figure
232. Check that all fittings are tight. Evacuate a 50-liter Tedlar or
aluminized Mylar bag that has passed a leak check (described in Section
7.3.2) and meter in about 50 liters of nitrogen. Measure the barometric
pressure, the relative pressure at the dry gas meter, and the temperature
at the dry gas meter. Refer to Table 23-1. While the bag is filling,
use the 50 yl syringe to inject through the septum on top of the impinger,
the quantity required to yield a concentration of 200 ppm. In a like
manner, use the 25 yl syringe to prepare bags having approximately 100
and 50 ppm concentrations. To calculate the specific concentrations,
refer to Section 8.1. Tedlar bag gas mixture standards of methylene
chloride, ethylene dichloride, and trichlorotrifluoroethane may be used
for 1 day; trichloroethylene and 1, 1,1-trichloroethene for 2 days;
perchloroethylene and carbon tetrachloride for 10 days from the date of
preparation. (Caution: Contamination may be a problem when a bag is
reused if the new gas mixture standard is a lower concentration than the
previous gas mixture standard.)
7.2 Calibration.
7.2.1 Determination of Halogenated Organic Compound Retention
Time. This section can be performed simultaneously with Section 7.2.2.
Establish chromatograph conditions identical with those in Section 6.3,
above. Determine proper attenuator position. Flush the sampling loop
with zero helium or nitrogen and activate the sample valve. Record the
50
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en
TABLE 23-1. INJECTION VALUES FOR PREPARATION OF STANDARDS. (Optional, see Section 7.1.1)
yl Liquid Required in 50 1
Compound
Perchloroethylene C2C1,
Trichloroethylene C2HC13
1 , 1 , 1 -Tr i chl oroethane C2H3C1 3
Methyl ene Chloride CH2C12
Tr i chl orotr i f 1 uoroethane C2C1 3F3
Carbon Tetrachloride CCl^
Ethyl ene Di chloride C9HAC19
Molecular
Weight
(M)
165.85
131.40
133.42
84.94
187.38
153.84
98.96
Density at
293° A
(D)
1.6230
1.4649
1.4384
1.3255
1.5790
1.5940
1.2569
for Approximate Concer
200 ppm 100 ppm
42.5
37.3
38.6
26.6
49.3
40.1
32.7
21.2
18.6
19.3
13.3
24.7
20.1
16.4
itration of:
50 ppm
10.6
9.3
9.6
6.7
12.3
10.0
8.2
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injection time, the sample loop temperature, the column temperature, the
carrier gas flow rate, the chart speed and the attenuator setting.
Record peaks and detector responses that occur in the absence of the
halogenated organic. Maintain conditions (with the equipment plumbing
arranged identically to Section 6.3), flush the sample loop for 30
seconds at the rate of 100 ml/min with one of the halogenated organic
compound calibration mixtures, and activate the sample valve. Record
the injection time. Select the peak that corresponds to the halogenated
organic compound. Measure the distance on the chart from the injection
time to the time at which the peak maximum occurs. This distance divided
by the chart speed is defined as the halogenated organic compound peak
retention time. Since it is possible that there will be other organics
present in the sample, it is very important that positive identification
of the halogenated organic compound peak be made.
7.2.2 Preparation of Chromatograph Calibration Curve. Make a gas
chromatographic measurement of each standard gas mixture (described in
Section 5.2.3 or 7.1.1) using conditions identical with those listed in
Sections 6.3 and 6.4. Flush the sampling loop for 30 seconds at the
rate of 100 ml/min with one of the standard gas mixtures and activate
the sample valve. Record C , the concentration of halogenated organic
\*
injected, the attenuator setting, chart speed, peak area, sample loop
temperature, column temperature, carrier gas flow rate, and retention
time. Record the laboratory pressure. Calculate AC> the peak area
multiplied by the attenuator setting. Repeat until two consecutive
injection areas are within 5 percent, then plot the average of those two
52
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values versus C . When ther other standard gas mixtures have been
similarly analyzed and plotted, draw a straight line through the points.
Perform calibration daily, or before and after each set of bag samples,
whichever is more frequent.
7.3 Quality Assurance.
7.3.1 Analysis Audit. Immediately after the preparation of the
calibration curve and prior to the sample analyses, perform the analysis
audit described in Appendix E, Supplement B: "Procedure for Field
Auditing GC Analysis."
7.3.2 Bag Leak Checks. While performance of this section is
required subsequent to bag use, it is also advised that it be performed
prior to bag use. After each use, make sure a bag did not develop leaks
as follows: to leak check, connect a water manometer and pressurize the
bag to 5-10 cm H20 (2-4 in. H20). Allow to stand for 10 minutes. Any
displacement in the water manometer indicates a leak. Also, check the
rigid container for leaks in this manner. (Note: an alternative leak
check method is to pressurize the bag to 5-10 cm hLO or 2-4 in. HgO and
allow to stand overnight. A deflated bag indicates a leak.) For each
sample bag in its rigid container, place a rotameter in line between the
bag and the pump inlet. Evacuate the bag. Failure of the rotameter to
register zero flow when the bag appears to be empty indicates a leak.
8. Calculations
8.1 Optional Standards Concentrations. Calculate each halogenated
organic standard concentration prepared in accordance with Section 7.1.1
as follows:
53
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r
C
3
P -| D pg 10 pg pg mole 24.055 pi
y pi mg M pg p§ mole
„ v 106 pi 293 Pm
vm Y 1 Tm 760
{£ (24.055 x 103)
u v 293 Pm
m Y ~T~ 760
106
E<
Equation 23-1
Where:
C = Standard concentration in ppm.
B = Number of pi of injected.
Vm = Gas volume measured by dry gas meter in liters.
Y = Dry gas meter calibration factor.
»
Pm = Absolute pressure of the dry gas meter, mm Hg.
T = Absolute temperature of the dry gas meter, °A.
D = Density of compound at 293° A.
M = Molecular weight of compound.
24.055= Ideal gas at 293° A, 760 mm Hg.
10 = Conversion factor, ppm.
8.2 Sample Concentrations. From the calibration curve described in
Section 7.2.2 above, select the value of Cc that corresponds to AC. Calcu-
late Cs as follows:
CcPrTi
Ce = p T y/g — r Equation 23-2
"
e
s
Where:
S . = The water vapor content of the bag sample, as analyzed.
C = The concentration of the halogenated organic in the sample
in ppm.
54
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C = The concentration of the halogenated organic indicated by
C
the gas chromatograph, in ppm.
Pr = The reference pressure, the laboratory pressure recorded
during calibration, mm Hg.
T.. = The sample loop temperature on the absolute scale at the
time of analysis, °A.
P.. = The laboratory pressure at time of analysis, mm Hg.
Tr = The reference temperature, the sample loop temperature
recorded during calibration, °A.
9. References
1. Feairheller, W. R.; Kemmer, A.M.; Warner, B. J.; and
Douglas, D. Q. "Measurement of Gaseous Organic Compound Emissions by Gas
Chromatography," EPA Contract No. 68-02-1404, Task 33 and 68-02-2818, Work
Assignment 3. January 1978. Revised August, 1978, by EPA.
2. Bullein 747. "Separation of Hydrocarbons" 1974. Supelco, Inc.
Bellefonte, Pennsylvania 16823.
3. Communication From Joseph E. Knoll. Perchloroethylene Analysis
by Gas Chromatography. March 8, 1978.
4. Communication From Joseph E. Knoll. Test Method for Halogenated
Hydrocarbons. December 20, 1978.
55
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TECHNICAL REPORT DATA
(Please read Inunictions on the reverse before completing)
1. REPORT NO.
EPA 600/4-79-025
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AMD SUBTITLE
EVALUATION OF EMISSION TEST METHODS FOR HALOGENATED
5. REPORT DATE
March 1979
HYDROCARBONS - VOLUME I, CC1.,
CpCl, and
6. PERFORMING ORGANIZATION CODE
7. ADTHOR(S)
Joseph E. Knoll, Mark A. Smith and M. Rodney Midgett
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Quality Assurance Branch
Environmental Monitoring and Support Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
10. PROGRAM ELEMENT NO.
1AD800
11. CONTRACT/GRANT NO.
12. SPONSORING AGENCY NAME AND ADDRESS
Environmental Monitoring and Support Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina ,27711
13. TYPE OF REPORT AND PERIOD COVERED
Final Report
14. SPONSORING AGENCY CODE
EPA-ORD-600
15. SUPPLEMENTARY NOTES
To be published as an Environmental Monitoring Series Report.
16. ABSTRACT
A test method for halogenated hydrocarbons has been evaluated and information is
provided for the user. Four compounds were investigated, carbon tetrachloride,
ethylene dichloride, tetrachloroethylene and trichloroethylene. The subject compound:
remained stable in compressed gas mixtures in aluminum and steel cylinders for 4
months. In Tedlar bags held at ambient temperatures, carbon tetrachloride and tetra-
chloroethylene remained stable for 10 days, trichloroethylene for 2 days, and ethylem
dichloride for one day. Heating causes decreases in stabilities. A procedure was
developed to remove persistent residues from Tedlar bags that had contacted high con-
centrations of halogenated hydrocarbons. Information is also included on gas chromati
graphic columns for use in this method of analysis.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Croup
air pollution
gas sampling
halogenated hydrocarbons
Tedlar bags
43 F
68A
13. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (This Report)
UNEIASSTFTFH
21. NO. OF PAGES
Rfi
20. SECURITY CLASS (Thispage)
UNCLASSIFIED
22. PRICE
EPA Form 2220-1 (9-73)
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