United States
Environmental Protection
Agency
Environmental Monitoring
Systems Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S4-85/075 Jan. 1986
v>ERA Project Summary
Laboratory and Field
Evaluation of the
Semi-VOST Method
J. Bursey, M. Hartman, J. Homolya,
R. McAllister, J. McGaughey, and D. Wagoner
An initial laboratory and field evalua-
tion has been completed which as-
sessed the performance of the Semi-
Volatile Organic Sampling Train
Method (Semi-VOST) for measuring
concentrations of principal organic haz-
ardous constituents (POHCs) with boil-
ing points greater than 100°C that are
emitted from hazardous waste inciner-
ators. A draft formulation of the
methodology was tested through an
experimental laboratory program to
evaluate method performance charac-
teristics. The program consisted of:
(1) determination of minimum com-
pound detection limits; (2) simulation
of a flue gas stream to determine the
impacts of water vapor, SO2, NOX, and
HCI on sampling; and (3) determination
of precision and bias for the sample
preparation and analytical elements of
the method. Results of the simulation
study are reported for 12 test com-
pounds (POHCs) representing a range
of physical and chemical properties
which could affect sample train collec-
tion and recovery performance. Three
of the test compounds (toluene,
chlorobenzene, and 1,1,2,2-
tetrachloroethane) were selected for
further investigation to evaluate
method precision and bias under field
conditions through the use of four
simultaneously-operating Semi-VOST
trains. Cylinder gas standards of each
compound were blended and dynami-
cally spiked into paired sample trains
for determining method bias. Estimates
of bias are presented for toluene and
1,1,2,2-tetrachloroethane. Method pre-
cision for chlorobenzene is calculated
from unspiked sample train results
which also included distributive vol-
ume experiments to determine sample
train breakthrough of POHCs. Project
results are presented in Volume I along
with recommendations on elements of
the method requiring further research.
Volume II includes appendices giving
detailed descriptions of the method for-
mulation, laboratory and field studies,
along with quality assurance data.
This Project Summary was devel-
oped by EPA's Environmental Monitor-
ing Systems Laboratory, Research Tri-
angle Park, NC, to announce key
findings of the research project that is
fully documented in two separate
volumes of the same title (see Project
Report ordering information at back).
Introduction
The Solid Waste Disposal Act, as
amended by the Resource Conservation
and Recovery Act of 1976 (RCRA), re-
.quires that the Environmental Protec-
tion Agency establish a national regula-
tory program to ensure that hazardous
wastes are managed in a manner which
does not endanger human health or the
environment. The statute requires EPA
to promulgate performance standards
for hazardous waste management. In-
cluded in the promulgated regulations
are provisions for waste disposal by in-
cineration and requirements that haz-
ardous waste incinerators be so oper-
ated that the principal organic
hazardous constituents (POHCs) are de-
stroyed or removed with a minimum ef-
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ficiency of 99.99 percent. To determine
destruction and removal efficiency
(ORE), EPA has designated the Semi-
Volatile Organic Sampling Train
Method (Semi-VOST) as the method for
measuring concentrations of POHCs
with boiling points greater than 100°C
that are emitted from hazardous waste
incinerators.
The Quality Assurance Division of the
Environmental Monitoring Systems
Laboratory at Research Triangle Park,
North Carolina, has a program to evalu-
ate and standardize EPA source test
methods. While participating in this
program, Radian Corporation has un-
dertaken an evaluation of the Semi-
VOST Method, which is the subject of
the full report. The following were the
objectives of the program:
• assemble and refine a draft formu-
lation of the Semi-VOST sampling
and analysis methodology;
• select a series of Appendix VIII test
compounds for method evaluation
based on the characteristics of in-
cinerability, water solubility, and
adsorption strength on XAD-2®
resin;
• design and conduct an experimen-
tal laboratory program to evaluate
method performance characteris-
tics in terms of minimum com-
pound detection limits, sampling
flow rate and volume, and the for-
mation of artifact compounds dur-
ing the sampling of a simulated flue
gas stream containing water vapor,
S02, NOX, and HCI;
• determine precision and bias at-
tributable to each of the sample
preparation steps and the final GC/
MS analysis step;
• design, construct, and evaluate the
performance of a dynamic spiking
system for determining method
bias using experimental field data;
and
• carry out a field test study at a haz-
ardous waste incineration facility to
evaluate method precision and bias,
and the potential of POHC sample
train breakthrough.
Procedure
The initial Semi-VOST method formu-
lation contained no analytical protocols
but included several sections that were
discretionary or that required clarifica-
tion. Therefore, prior to laboratory ex-
perimentation, a refinement in the for-
mulation was developed by surveying
members of the technical community
who had experience in the use of the
Semi-VOST method. Based on the sur-
vey responses, a working copy of the
method was drafted to encompass both
sampling and analysis procedures.
In the application of Semi-VOST,
gaseous and particulate components
are isokinetically withdrawn from an
emission source and collected in a mul-
ticomponent sampling train. Key ele-
ments of the train include a high-
efficiency particulate filter and a packed
bed of a porous polymeric adsorbent
resin (XAD-2®). The filter is used to sep-
arate stack gas particles from gaseous
substances, which are then adsorbed
on XAD-2®. As a collection sorbent,
XAD-2®, a polystyrene-divinylbenzene
copolymer, has the advantage of high
surface area (300 rq,2/g) with an average
pore volume of 90 A, which permits col-
lection of semi-volatile compounds. Fol-
lowing sample collection, the train com-
ponents are extracted with solvent,
concentrated, and identified/quantified
using high resolution gas chromatogra-
phy coupled with low resolution mass
spectrometry.
After return of the samples to the lab-
oratory, all fractions are spiked with sur-
rogate standards prior to extraction,
concentration, and analysis. The use of
surrogates provides a measure of the
efficiency of the sample preparation
procedures. In the sample analyses, an
examination of surrogate recovery is
used to qualify and possibly correct the
analytical results. For example, poor or
variable surrogate recovery would sug-
gest difficulties with sample prepara-
tion/analysis as opposed to incinerator
operation. The spiking compounds
should be the stable, isotopically-
labeled analogs of the compounds of
interest or a compound that would ex-
hibit properties similar to those of the
compounds of interest, be easily chro-
matographed, and not interfere with the
analysis. Potential surrogate spiking
compounds include deuterated naph-
thalene, chrysene, phenol, nitroben-
zene, chlorobenzene, toluene, and car-
bon 13-labeled pentachlorophenol.
The condensate knockout trap solu-
tion is spiked with the surrogates, trans-
ferred to a separatory funnel, acidified,
and extracted with methylene chloride.
The aqueous phase is made alkaline
and re-extracted with methylene chlo-
ride. This procedure is used to optimize
the recovery of POHCs with different
functional groups. The condensate may
contain compounds that show great
water solubility and low organic solvent
solubility. The methylene chloride solu-
tions are combined in a Kuderna-Danish
(K-D) evaporator/concentrator and re-
duced in volume usually to less than
10 ml, and a standard is added for quan-
titation by gas chromatography coupled
with mass spectrometry (GC/MS). Im-
pinger contents are extracted with
methylene chloride under both acidic
and basic conditions and then concen-
trated. The methylene chloride/
methanol rinses of the probe and filter
housing are prepared by spiking with
surrogate standards and adding suffi-
cient water to a separatory funnel to
force methylene chloride to become im-
miscible with water and form two
phases. The XAD-2® resin is spiked with
surrogate standards and transferred
with the filter to an all-glass Soxhlet ex-
traction thimble. The module is rinsed
with methylene chloride, the solution is
added to the Soxhlet, and extraction is
conducted for 16 hours.
Analysis is performed by GC/MS
using fused silica capillary GC columns.
The mass spectrometer is operated in a
full (40 to 450 daltons) scanning mode.
For most purposes, electron ionization
(El) spectra are collected, since a major-
ity of the potential POHCs give reason-
able El spectra. Also El spectra are com-
patible with the NBS Library of Mass
Spectra and other reference data that
aid in identification.
For quantitation by GC/MS, each sam-
ple fraction is spiked with a known
amount of an internal standard prior to
analysis. The response ratio of the inter-
nal standard to each compound of inter-
est in the sample is then compared to a
similar ratio established with a calibra-
tion curve.
Results and Discussion
Laboratory Evaluation
A laboratory program consisting of
three stages was designed and imple-
mented to provide an initial estimate of
method precision and bias and to inves-
tigate method interferences. The initial
portion of the laboratory program in-
volved the selection of compounds to
test the limits of the method and for the
determination of minimum detection
limits (MDL) of the GC/MS. Compound
selection was followed by a series of
simulated flue gas generation experi-
ments to identify external effects of the
sampling environment that would affect
the analytical results and to evaluate the
overall method precision and bias. Fi-
nally, a series of experiments was con-
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ducted to determine specifically the pre-
cision and bias of the laboratory
preparation and analytical portions of
the method.
Results from the laboratory studies
indicated the following:
• Method precision and bias are
compound-specific and cannot be
generalized for all classes of chemi-
cals. Laboratory experiments
demonstrated that method preci-
sion and bias are related to the
distribution and recovery of a par-
ticular POHC throughout the com-
ponents of the sampling train. Sam-
ple distribution and recovery of a
POHC is related to its boiling point,
water solubility, and chemical func-
tion.
• Compounds adsorbed on XAD-2®
resin exhibited better precision and
recovery than compounds collected
in the condensate and impingers.
• Test compound recoveries were not
affected by either simulated flue gas
variations in compound concentra-
tion by HCI, S02, or water vapor, or
by variations in sample flow rate
and volume.
• Increases in generated flue gas NOX
levels were associated with de-
creases in the recoveries of 1,4-
dioxane, urethane, and phenol.
• For toluene, chlorobenzene, and
1,1,2,2-tetrachloroethane, labora-
tory experiments showed that the
precision of the resin extraction and
concentration steps was not signifi-
cantly different from the precision
of the concentration step alone.
However, the precision of the sepa-
ratory funnel extraction and con-
centration steps was significantly
poorer than either the precision of
the concentration step alone or the
resin extraction and concentration
step.
• For chlorobenzene, toluene, and
1,1,2,2-tetrachloroethane, no signif-
icant losses were detected when the
K-D concentrate was reduced from
5 ml to 2.5 ml using an inert gas for
blowdown.
Field Evaluation
Following completion of the labora-
tory studies, a field test program was
conducted to evaluate method perform-
ance at an operational hazardous waste
incineration facility. A test plan was pre-
pared which included the collection of
matrixed sequence of samples for the
evaluation of method precision, bias,
and POHC sample train breakthrough.
Results from the field evaluation
study included the following:
• A preliminary estimate of method
bias of -13 percent for toluene was
calculated from field test data ob-
tained using the dynamic spiking
system.
- The 87 percent recovery of
toluene from the field test data
compares favorably with the
mean recovery of 91 percent
measured from the laboratory
baseline performance test of the
dynamic spiking apparatus.
- The identification of toluene in
the methylene chloride recovery
solvent returned from the field
necessitates analysis of addi-
tional sample fractions from the
test to confirm the toluene bias
estimate.
• A preliminary estimate of method
bias of -16 percent was calculated
for 1,1,2,2-tetrachloroethane.
- The 84 percent recovery of
1,1,2,2-tetrachloroethane is in
agreement with the 85 percent
value from the baseline dynamic
spiking test.
• The dynamic spiking concept was
demonstrated as a viable approach
for determining method bias in field
evaluation studies.
• A method precision of 19.9 percent
for chlorobenzene was calculated
from a field test data set consisting
of a series of paired, unspiked Semi-
VOST trains sampling the emis-
sions from a hazardous waste incin-
erator.
• No sample train breakthrough of
chlorobenzene could be determined
from the field test distributive vol-
ume experiments. Therefore, the re-
tention volume for chlorobenzene
was not exceeded and demon-
strates the adequacy of this aspect
of the current method formulation.
Recommendations
Based on the results of the method
evaluation studies presented in this re-
port, the following recommendations
are made for further investigation:
• Method bias and precision have
been shown to be compound
specific. An investigation should be
conducted to determine if Ap-
pendix VIII compounds could be ag-
gregated according to properties
such as water solubility, chemical
similarity, or adsorption strength
(retention volume) on XAD-2 to pro-
vide estimates of method precision
and bias for compound categories.
Pyridine, pentachlorophenol, and
resorcinol exhibited poor recoveries
during the flue gas generator exper-
iments. Preliminary studies have in-
dicated that compound losses may
be attributed to chromatographic
properties, poor solvent extraction,
or compound reaction in the
aqueous components of the sam-
pling train which become acidified
during sample collection. Also, the
low recovery of pentachlorophenol
may have been due to loss within
the flue gas generator. Further labo-
ratory studies are warranted to clar-
ify these observations and to de-
velop simplified screening
procedures to demonstrate the ap-
plicability of the method's sample
preparation (extraction) and analy-
sis (GC/MS conditions) steps to
other Appendix VIII compounds or
classes of compounds.
The recovery losses of urethane,
phenol, and 1,4-dioxane associated
with NOX flue gas generator levels
should be studied using solutions to
simulate condensate and impinger
contents for evaluating compound
reactivity with NOX. Findings could
then be used to plan a second field
evaluation of the method which in-
cludes POHC artifact formation
study objectives.
The particulate filters from the
Semi-Vost samples collected during
the field test program were stored
and solvent extracted for later anal-
ysis. The extracts should be ana-
lyzed for semi-volatile compounds
in preparation for future studies
to evaluate POHC-particulate mat-
ter interactions during sample
collection.
The preliminary estimates of
method bias for toluene and 1,1,2,2-
tetrachloroethane should be final-
ized by analyzing the remaining
sample fractions from the field test.
The presence of toluene in the
methylene chloride rinse solvent
should also be accounted for.
The dynamic spiking system for
determining method bias should be
redesigned to improve its reliability
in the field. The use of a stable,
single gas mixture containing multi-
ple components would simplify op-
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eration and delivery of a dynamic
spike to two simultaneously-
operating Semi-Vost trains. Stable,
isotopically-labeled POHCs would
be desireable spiking components
as it is unlikely that they would be
present in the flue gas.
The existing field study GC/MS ana-
lytical data set for unspiked sam-
pling runs should be re-examined to
determine if additional flue gas or-
ganic compounds could be used to
evaluate sample train break-
through.
Future field method evaluation
studies should include the addition
of spiked waste feed materials to
permit measurement of method
precision and sample train break-
through for several pre-determined
compounds contained in the spiked
waste.
J. Bursey, M. Hartman, J. Homolya, R. McAllister, J. McGaughey, andD. Wagoner
are with Radian Corporation, Research Triangle Park, NC 27709.
John Margeson is the EPA Project Officer (see below).
The complete report consists of two volumes, entitled "Laboratory and Field
Evaluation of the Semi-VOST Method:"
"Volume I," (Order No. PB 86-123 551 /A S; Cost: $11.95)
"Volume II. Appendices." (Order No. PB 86-123 569/AS; Cost: $22.95)
The above reports will be available only from: (cost subject to change)
National Technical Information Service
5285 Port Royal Road
Springfield. VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Environmental Monitoring Systems Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
tnvironmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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