United States
Environmental Protection
Agency
Air and Energy Engineering
Research Laboratory
Research Triangle Park NC 27711
Research and Development
EPA/600/S8-87/008 May 1987
SERA Project Summary
Development of VOST Sample
Analysis Protocol for
Water-Soluble Volatile
POHCs and PICs
Mark H. Owens, Stephen A. Mooney, and Thomas Lachajczyk
This report gives results of a literature
review and laboratory research associ-
ated with applying the volatile organic
sampling train (VOST) to the sampling
and analysis of water-soluble, volatile.
Principal Organic Hazardous Constitu-
ents (POHCs) and Products of Incom-
plete Combustion (PICs). Previous
studies resulted in methods develop-
ment for analysis of volatile POHCs and
PICs, but did not address compounds
soluble in water.
The POHCs and PICs studied were
acetaldehyde, acetone, acetonitrile,
acrolein, acrylonitrile, 1,4-dioxane,
ethyl acetate, methyl ethyl ketone,
methyl formate, propionitrile, propyla-
mine, and pyridine. The collection ef-
ficiency of each component of the VOST
was established for each compound.
The accuracy of current analytical
methods for analysis of volatile POHCs
and PICs when applied to volatile,
water-soluble POHCs and PICs was
determined. New analytical techniques
were developed through literature
search and experimentation, and were
evaluated against existing methods. An
accuracy goal of 60-150% pollutant
recovery was set, along with an analy-
tical goal of 25% or less relative
difference.
Modifications to the existing method
of analysis (purge and trap) include
elevating the purge temperature from
the standard (20°C) to 60°C, adding 1
g of either sodium chloride or sodium
sulfate salt to the sample before purging,
and a combination of both modifica-
tions. The modifications improved purge
efficiency by about 100% or more for
the compounds analyzed. Even with
the modifications, the highest purge
efficiency for 1,4-dioxane was no
greater than 21%. The resulting purge
efficiencies for these compounds ranged
from 19.1% for 1,4-dioxane to 127%
for acetaldehyde.
The alternate analytical method of
direct aqueous injection into a liquid
chromatograph was performed with
condensate from the pyridine VOST
analysis. VOST recovery of pyridine
with this analytical method was at best
23%. Other compounds (acrolein,
acrylonitrile, 1,4-dioxane, and methyl
formate) did not meet the VOST re-
covery objective of 6O-15O% recovery.
Pyridine was analyzed by direct aqueous
injection on the liquid chromatograph
because the purge efficiency was poor
and the liquid chromatograph offered a
viable alternative.
This Project Summary was developed
by EPA's Air and Energy Engineering
Research Laboratory, Research Triangle
Park, NC, to announce key findings of
the research project that Is fully docu-
mented In a separate report of the same
title (see Project Report ordering In-
formation at back).
Background
Sampling and analysis for determina-
tion of the concentration of organic pol-
lutants in stack gas effluents present
unique problems due to the minute con-
centrations involved and the variety of
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compounds present. Exacting analytical
procedures using advanced equipment
are required. One of these methods,
developed after years of research, is the
Volatile Organic Sampling Train (VOST).
The VOST was developed by the U.S.
EPA to sample volatile organic chemical
constituents in smoke stacks. One appli-
cation of VOST is the sampling of gaseous
effluent from hazardous waste incinera-
tors. The primary goal of this sampling is
to determine the destruction and removal
efficiency (ORE) of volatile Principal
Organic Hazardous Constituents (POHCs)
and Products of Incomplete Combustion
(PICs). DRE calculations are used to
demonstrate compliance with federal
regulations.
A protocol for sampling and analysis of
volatile POHCs and PICs with VOST has
been developed. However, it did not pro-
vide guidance for analysis of volatile
POHCs and PICs that are water-soluble.
Under an EPA contract, the VOST
procedures were evaluated with regard
to water-soluble, volatile POHCs and PICs
in order to develop an addendum to the
existing VOST sampting and analysis
protocol. A literature search and labora-
tory research were conducted into the
analytical methods associated with the
application of the VOST method to water-
soluble, volatile POHCs and PICs. The
results of that research are summarized
in this document.
The sample collection media in the
VOST include a Tenax trap, a condensate
collector, and a Tenax/charcoal trap. The
standard method of analysis for a volatile
POHC or PIC involves a thermal desorption
unit, purge and trap apparatus, and a
GC/MS. The purge and trap procedure
specified in the existing protocol may not
be suitable for analysis of some water-
soluble, volatile POHCs and PICs. This
document summarizes results of experi-
ments to develop modified methods of
analysis for those situations in which the
VOST may be used to sample water-
soluble volatile POHCs and PICs.
Objectives
The primary objective of this project
was to provide technical information for
the development of a protocol for VOST
sampling of volatile, water-soluble POHCs
and PICs. In order to accomplish the
primary objective, four secondary objec-
tives were identified:
1) Identification of suitable representative
water-soluble compounds for use in
methods analysis and development.
2) Determination of the accuracy of cur-
rent analytical methods for analysis of
water-soluble, volatile POHCs and
PICs.
3) Development of new analytical tech-
niques through literature search and
experimentation, and evaluation of
these techniques by comparison to
existing methods.
4) Determination of the collection effici-
ency of each component of the VOST
for each compound.
Scope of Work
Compounds were identified for study
based on criteria developed in the plan-
ning phase. Ten compounds were then
evaluated with regard to purge efficiency.
Then, modifications and alternatives to
the purge and trap method were devel-
oped, evaluated, and compared to estab-
lish a preferred analytical technique.
Finally, VOST experiments were run for
selected compounds, and recovery effici-
encies for each component of the VOST
(i.e., Tenax trap 1, condensate, Tenax trap
2, and charcoal trap) were determined
using the preferred analytical technique.
Although the overall objective of the pro-
ject included development of modifica-
tions to the analytical protocol, it was
beyond the scope of the project to develop
modifications to the sampling protocol
(e.g., substitution for Tenax).
Summary and Conclusions
Analytical Method Modification
Summary
The standard purge and trap procedure
for analyzing volatile POHCs and PICs in
VOST impinger condensate was con-
sidered potentially inadequate when used
to analyze water-soluble volatile POHCs
and PICs. Improved analytical techniques
were developed and evaluated. Modifica-
tions to the standard purge and trap
method included elevating the purge
temperature to 60°C and adding 1 g of
sodium chloride or sodium sulfate salt to
the condensate before purging. An alter-
native analytical method using direct
aqueous injection in a high pressure
liquid chromatograph (HPLC) was also
investigated.
The basis of comparison between
alternate methods was purge efficiency,
defined as the ratio of the GC/FID curve
area response generated by a given
quantity of pollutant after purge and trap
of the pollutant, to the direct aqueous
injection into the GC/FID.
The mean purge efficiency for the 12
compounds studied, at room temperature
purge without salt addition, was 20.7%,
and ranged from 0.0% for pyridine to
44.6% for acrolein. The mean purge ef-
ficiency using alternate optimal methods
was more than 3.7 times greater.
Analytical Results Summary
The highest recovery efficiencies
achieved for each POHC or PIC evaluated
using the VOST are given in Table 2-1 of
the full report. These recovery efficiencies
are the cumulative pollutant recoveries
achieved through the combined collection
in all components of the VOST system
(Tenax trap 1, condensate impinger, Tenax
trap 2, and charcoal trap), divided by the
standard weight used in the VOST run.
The recovery values reported were the
highest cumulative recoveries demon-
strated through a series of three runs for
each compound, using standard (un-
modified) VOST analytical protocol.
Conclusions
1) The VOST protocol for sampling and
analysis of volatile POHCs and PICs
can be adapted to include the analytical
protocol for some volatile, water-
soluble POHCs and PICs.
2) The distribution of the trapped com-
pounds in the various components of
the VOST train (Tenax trap 1, con-
densate trap, Tenax trap 2, and char-
coal trap) is highly variable and
appears to be compound-specific.
3) Purge efficiency of VOST condensate
can be greatly enhanced by elevating
the purge temperature and by salting
the sample with 1 g of NaCI or Na2S04
before purging. However, even with
these modifications, purge efficiency
for some compounds, though improved,
will still be low.
4) Na2SO4 appears to improve purge ef-
ficiency to a greater extent than NaCI
when used in similar circumstances
(i.e., in conjunction with a 60°C purge
temperature).
5) VOST recoveries of 60-150% were
demonstrated using the methods men-
tioned above for five water-soluble,
volatile POHCs and PICs: acetaldehyde,
acrylonitrile, ethyl acetate, methyl ethyl
ketone, and propionitrile.
6) VOST recoveries of 60-150% were
not demonstrated, even with the
methods mentioned above, for five
water-sol,uble, volatile POHCs and
PICs: acetonitrile, acrolein, 1,4-
dioxane, methyl formate, and pyridine.
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M. Owens, S. Mooney. and T Lachajczyk are with Envirodyne Engineers, Inc.,
St. Louis, MO 63146.
Larry D. Johnson is the EPA Project Officer (see below).
The complete report, entitled "Development of VOST Sample Analysis Protocol
for Water-Soluble Volatile POHCs and PICs," (Order No. PB 87-165 239/
AS; Cost: $18.95, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield. VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Air and Energy Engineering Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
Official Business
Penalty for Private Use $300
EPA/600/S8-87/008
0000329 PS
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