United States
Environmental Protection
Agency
Atmospheric Research and Exposure
Assessment Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S3-90/065 Sept. 1990
EPA Project Summary
Sampling and Analysis of
Butadiene at a Neoprene Plant
Anna C. Carver
Butadiene has been listed as a haz-
ardous air pollutant by the Un ited States
Environmental Protection Agency (EPA).
This document details a field study
commissioned bythe EPA's Atmospheric
Research and Exposure Assessment
Laboratory, Quality Assurance Division,
Research Triangle Park, North Carolina,
that validates a method for the sampling
and analysis of butadiene emissions from
a plant manufacturing neoprene from
butadiene/chlorine mixtures. Gaseous
samples werecollectedfromthe process
vent of one such plant using a modifi-
cation of the evacuated container sam-
pling procedure,outlined in Section 7.1.1
of EPA Method 18. The samples were
collected at a sampling rate of 0.04 L/
min, rather than at 0.5 L/min as specified
in the method. Sample collection at the
lowered sampling rate yields a total
sample volume of approximately 3 L,
rather than the 30 L obtained when using
the specified sampling rate. On-site
analysis of samples was performed us-
ing a gas chromatograph equipped with
a flame ionization detector.
The method precision was deter-
mined by collection and analysis of si-
multaneous.quadruplicate samples. The
relative standard deviation for quad-train
samples collected at the lowered sam-
pling rate ranged from 1.7 - 6.4 percent
with emission levels ranging from about
2 to 40%.
This Project Summary was devel-
oped by EPA's Atmospheric Research
and Exposure Assessment Laboratory,
Research Triangle Park, NC, to an-
nounce 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).
Procedure
The principles of sampling and analy-
sis followed the general procedures de-
scribed in EPA Method 18, with the excep-
tion that emission samples were collected
at flow rates of 0.04 L/min, rather than 0.5 L/
min.
The precision of the sampling and
analysis techniques was determined using
quad-trains. During the field test, gases
were withdrawn from a duct carrying pro-
cess emissions to the atmosphere, and all
quad-trains drew gases from a common
manifold. A schematic of the sampling
apparatus is included as Figure 1.
Samples were collected in quadrupli-
cate in 5 L Tedlar bags using a newly
designed sampling system. All bags were
analyzed on-site, as was an audit sample.
The results from analysis of the four bags
were averaged, and a standard deviation at
95% confidence level for each sampling
run were calculated.
One bag sample from each of the
sampling runs was returned to the base
laboratory for reanalysis by Entropy.
These samples were analyzed 13 to 15
days following completion of the field test.
Following reanalysis at Entropy's laboratory,
selected bag samples were made available
to AREAL, QAD personnel for independent
verification of butadiene concentrations
measured.
Analyzed cylinders containing approxi-
mately 2000 ppm, 1.3%, and 3.8% of gas-
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sous butadiene in nitrogen were purchased
from a supplier of high purity gases and
used to calibrate the gas chromatograph.
The cylinders were analyzed after final
blending by the supplier, who certified the
butadiene concentrations to ± 5 ppm.
Instrument response was obtained
from a least squares fit of the calibration
data. An audit of these results was con-
ducted daily by assaying the concentration
of a blind audit sample provided under the
EPA's performance audit program. The
audit sample contained butadiene diluted
with nitrogen gas at a concentration in the
ppm range.
The accuracy of the butadiene deter-
minations was examined by the on-site
analysis of a blind audit sample provided by
Research Triangle Institute, Research Tri-
angle Park, North Carolina underthe EPA's
performance audit Figure 1. Quad-train
sampling system program, which utilizes
cylinder gases containing volatile organics
in the ppm range. The audit cylinders
available were known to contain butadiene
in the 5-60 ppm range. Field and labora-
tory analyses of the cylinder provided a
quality assurance check of the three-point
calibration curves.
During the field test, sample analysis
involved a chromatographic system utiliz-
ing a 2 m x 1/8-inch stainless steel column
containing 0.19% picrtcacid on 80/100 mesh
Carbopack C. The separation was per-
formed isothermally at 80°C, and the carrier
flow was approximately 30 mL/min in the
forward direction.
Results and Discussion
The range and sensitivity were deter-
mined for the Tedlar bag sampling tech-
nique prior to conducting the field test. An
estimation of the limit of detection and
quantifiable limit was made. Using asample
size of 1 ml, these values were determined
to be 0.43 ppm and 2.0 ppm, respectively.
The results from analysis of the four
bags composing each quad-train were av-
eraged, and a standard deviation at 95%
confidence level were calculated. The rela-
tive standard deviation was also calculated
for each of the 12 sampling runs. One
relative standard deviation was discarded
as a statistical outlier at a confidence level
of 90%. Two estimates for measures of the
precision of the method are given, one in
which the outlier is included and one in
which it is not. The relative standard de-
viations ranged from 1.7 to 6.4 percent.
During the quad-train sampling runs, the
average butadiene level determined using
samples collected in the bags at a flow rate
of 0.04 L/min was approximately 27%. This
information is summarized in Table 1.
A stability study of the samples col-
lected indicated that butadiene at these
high levels (2-40%) is not necessarily stable
over long periods of time. After 13 days, the
samples began to show signs of polymer-
ization of the butadiene.
Several analyses of the audit cylinder
were conducted while analyzing samples
collected during the field test. The average
value obtained for the concentration of the
audit cylinder was only 4% above the certi-
fied concentration.
been proven acceptable at the 95%
confidence level greatly reduces the
sample size. This reduced sample
size allows sample collection in much
smaller and more convenient
sample containers.
2. The precision ranges from 1.7 to 6.4
percent for this method based on
the relative standard deviations ob-
tained in the field evaluation.
Table 1. Summary of Analytical Results and precision of Data
Date
4/2/90
4/3/90
4/3/90
4/3/90
4/3/90
4/3/90
4/4/90
4/4/90
4/4/90
4/4/90
4/4/90
4/4/90
Run
ID
1
2
3
4
5
6
7
8
9
10
11*
12
Mean
Cone. (%)
25.7 ,
33.9
35.5
37.5
20.2
24.0
41.4
34.2
22.8
2.55
15.7
26.9
Coefficient of
Variation (%)
_ 4.44
1.70
2.46
2.53
6.03
5.77
2.28
1.86
6.40
13.5
4.83
6.01
"One bag sample collected during this run was found to leak; the results from analysis of
this bag are not included in any statistical evaluation of the data.
Although the retention of butadiene by
Tedlar bags was not rigorously evaluated,
experiments were conducted to demon-
strate that bags containing field samples
could be reused afterthey had been blanked.
Bags were emptied of sample by complete
evacuation and flushed four times with
compressed air before being filled to half
their capacities. After allowing the bags to
stand overnight, analysis of the contained
gas showed them to be essentially free of
butadiene.
Conclusions and
Recommendations
The sampling and analytical pro-
tocol used wasfully validated, incorporating
the use of the lowered sampling rate for
collection of emission samples in small
Tedlar bags. The physical and chemical
composition of the process effluent encoun-
tered in this investigation leads to several
important conclusions/recommendations
concerning sampling methodology and
sample analysis.
1. A sample flow rate (approximately
0.05 L/min) is recommended for the
collection of butadiene at neoprene
plants. This flow rate which has
3. The possible presence of butane/
butene isomers in the sample stream
necessitates the use of a chroma-
tography column capable of sepa-
rating butadiene from these poten-
tial interferents. A 2 m x 1/8-inch
stainless steel column containing
0.19% picric acid on 80/100 mesh
Carbopack C was utilized during
this investigation. Use of this col-
... umn or another one of similar design
capable of resolving butadiene from
these potentially interfering hydro-
carbons is highly recommended.
4. Sample stability is a concern when
collecting butadiene at neoprene
plants due to the high concentra-
tions (2 - 40%) observed. Samples
appear to be stable upto two weeks,
but no longer. Rapid analysis of the
samples is highly recommended and
will eliminate the possibility of poly-
merization of butadiene before
sample analysis.
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1/4" TEFLON
VACUUM LINES -
STAINLESS STEEL
VACUUM MANIFOLD
BULK-HEAD
QUICK CONNECTS
STAINLESS STEEL
SAMPLE MANIFOLD
/ / VACUUM LINE (1501)
1/4" TEFLON
SAMPLE LINES
(41)
TRANSPARENT GLASS-
CONTAINERS
Figure 1. Quad-train sampling system.
S. GOVERNMENT PRINTING OFFICE: 1990/748-01-2/20102
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Anna C. Carver is with Entropy Environmentalists, Inc., Research Triangle Park, NC 27711
Jtmmy C. Pair is the EPA Project Officer (see below).
Tha complete report, entitled "Sampling and Analysis of Butadiene at a Neoprene Plant,"
(Order No. PB90-261 S46/AS; Cost: $17.00, cost subject to change) will be available only
from:
National Technicallnformation Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
Tha EPA Project Officer can be contacted at:
Atmospheric Research and Exposure Assessment 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/S3-90/065
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