United States
                    Environmental Protection
Industrial Environmental Research
Research Triangle Park NC 27711
                    Research and Development
EPA-600/S8-84-007  Apr. 1984
SEPA         Project  Summary
                    Protocol  for  the  Collection  and
                    Analysis  of  Volatile  POHCs
                    Using  VOST
                    Earl M. Hansen
                      This document provides a state-of-
                    the-art operating protocol for sampling
                    and analysis of volatile organic constit-
                    uents of flue gas from hazardous waste
                    incinerators or other similar combustor
                    systems using the Volatile Organic
                    Sampling Train (VOST). It is intended to
                    be used for guidance by personnel of
                    the regulatory groups, personnel asso-
                    ciated with engineering R&D. and the
                    regulated community.
                      The VOST is designed to extract and
                    concentrate volatile organic  com-
                    pounds (boiling point < 100C) from
                    stack gas effluents. The concentrated
                    organics are analyzed by procedures
                    chosen to be compatible with the VOST
                    in order to obtain flue gas concentration
                    levels. This information is necessary to
                    perform destruction and removal effi-
                    ciency (ORE) calculations for incin-
                    erator operations. The results of labo-
                    ratory evaluation and field use of the
                    VOST have shown that the VOST pro-
                    vides sufficient sensitivity to permit
                    calculation of a DRE equal to or greater
                    than 99.99 percent for volatile organics
                    present in the waste feed at 100/u g/g.
                      The VOST is directly applicable to
                    organic compounds with boiling points
                    of 30C to 100C. Many organic com-
                    pounds with boiling points less  than
                    30C or with  boiling  points in the
                    100C to  150C range may also be
                    collected and analyzed by this method.
                    Field application of the VOST for com-
                    pounds with boiling points outside the
                    30C-100C range should be attempt-
                    ed only after laboratory evaluation of
                    the collection and recovery efficiencies
                    of the specific compounds.
  The document is presented in two
parts. Part A describes the key compo-
nents of the train, the procedures for
preparation of the sorbent materials,
and procedures for sample collection
using the VOST. Part B describes the
procedures for analysis of VOST sorbent
cartridges for volatile principal organic
hazardous constituents (POHCs) using
purge-trap-desorb gas chromatogra-
phy/mass spectrometry (P-T-D GC/
MS). Quality control procedures  are
presented in both Sections A and B.
  This Project Summary was developed
by EPA's Industrial Environmental Re-
search 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 infor-
mation at back).

  The Resource Conservation and  Re-
covery Act (RCRA) requires that own-
ers/operators of facilities which treat
hazardous waste by incineration ensure
that the  incinerators  are operated  in a
manner which does not endanger human
health or the environment. The Code of
Federal Regulations, Title 40, Part 264,
requires  that a destruction and removal
efficiency of 99.99 percent be achieved
for each  POHC designated in the Trial
Burn Permit. The DRE standard implicitly
requires sampling and analysis to quanti-
fy POHCs in the waste feed material and
stack gas effluent. The "Sampling  and
Analysis  Methods for Hazardous Waste
Combustion" manual (methods manual)
provides information on methods that are

applicable for collection and analysis of
POHCs in process streams of hazardous
waste incinerator units.
  The methods manual identifies three
possible  methods for  the collection of
volatile organics (those with boiling points
of <100C). The methods include bag,
glass bulb, and the VOST. Evaluation of
the bags and bulbs indicates that these
sampling systems are subject to a number
of technical problems. The most important
of these problems is the  inadequate
sensitivity for  POHCs present  in  low
  The VOST provides increased sensitiv-
ity to low-level concentrations of volatile
POHCs due  to its ability to concentrate
the gaseous effluent. The  results of
laboratory evaluation and field application
of the VOST  have shown that it provides
sufficient sensitivity to permit calculation
of a  ORE equal to or greater than 99.99
percent for  volatile POHCs  which are
present in the waste feed at 10O^i g/g.
  The  methods manual  identifies the
VOST as a suitable sampling system for
volatile organics and  includes a paper
describing the VOST. A detailed protocol
was not included in the methods manual
due to the fact that this  is  outside the
scope of the  document.
  The  purpose of this  protocol  is to
provide a standard operating procedure to
users of the VOST in the collection and
analysis of samples for volatile POHCs in
the gaseous effluents of hazardous waste
incinerators  or gaseous effluents of haz-
ardous waste co-fired  combustion  proc-
esses. The protocol is presented in two
parts. Part A describes the  key compo-
nents of the VOST train, and the pro-
cedures for sample collection using VOST.
Part B describes  the procedures for
analysis  of VOST sorbent cartridges for
volatile POHCs using purge-trap-desorb
gas chromatography/mass spectrometry
(P-T-D GC/MS).

Part ASampling
  The VOST is directly applicable to
organic compounds with boiling points of
30Cto 100C. Many organic compounds
with boiling points below 30C and
between 100C and 150C  may also be
effectively collected and analyzed  using
the method  However, laboratory evalua-
tion of the collection and recovery efficien-
cies for  compounds with boiling points
outside  the 30C to 100C range is
required prior to field sampling.
  A schematic  diagram of the principal
components of the VOST is shown in
Figure 1 The gas stream  is filtered
through a glass wool plug in a quartz or
  Glass Wool
               Heated Probe
                      -Isolation Valves
                            .Carbon Filter
(or Test System)
                                                              Dry Gas
                                          Silica Gel
               Trap Impinger
Figure 1.    Schematic of Volatile Organic Sampling Train (VOST).
glass lined probe. The gas is then cooled
to 20C  by passage through  a  water
cooled condenser to facilitate collection
of volatile organic POHCs on a pair of
sorbent cartridges. Liquid condensate is
collected in an impmger placed between
the two  sorbent  cartridges. The first
sorbent cartridge contains approximately
1,6 g of Tenax, and the second cartridge
contains approximately  1  g of Tenax
followed by  1  g  of  petroleum based
charcoal, 3:1 by volume. Isolation valves
provide for purging the probe with stack
gas prior to sampling and for leak check-
ing the VOST
  Laboratory data have been developed
for a concentration range of 0.1 to  100
/ug/m3 (0.1 to  100 ng/L) for  selected
volatile POHCs. The concentration range
of 100/ug/m3 to 500/ug/m3 (100 ng/L to
500 ng/L) is not expected to pose prob-
lems.  Although the  upper end of the
range of applicability is limited by break-
through of  volatile POHCs  through the
sorbent cartridges used  to  collect the
sample,  the  range is also limited by
analytical constraints. Caution should be
exercised in using the VOST to collect
samples from a stack gas stream present
at high concentrations, 500^g/m3 (500
ng/L) or  greater. The analytical detector
may overload during analysis resulting in
invalid data. It would be  appropriate to
collect a reduced sample  volume to
alleviate  the  problem. Analytical prob-
lems such as peak interferences due to
peak tailing or instrument overloading
need to be  evaluated prior to field sam-
  The  VOST is designed to provide six
stack gas samples over a 2-hour sampling
                                        period.  The samples are collected at a
                                        sampling flow rate of 1 L/min, using a
                                        VOST equipped with a temperature con-
                                        trolled quartz or glass-lined probe.
                                          An alternate set of operating conditions
                                        allows  for reduced sample  flow  rate.
                                        Operation of the  VOST under these
                                        conditions has been referred to as SLOW-
                                        VOST. This method is used to collect 5 L
                                        of sample (0.25 L/min for 20 minutes) or
                                        20 L of sample (0.5 L/min for 40 minutes)
                                        on each pair of  sorbent cartridges. The
                                        SLOW-VOST should be considered  for
                                        sampling organic compounds with boiling
                                        points below 30C. Fewer pairs of car-
                                        tridge samples may be required for the
                                        SLOW-VOST with  a minimum of three
                                        sorbent cartridges samples collected.

                                        Part BAnalysis
                                          The method of analysis for volatile
                                        POHCs collected on VOST sorbent car-
                                        tridges is thermal desorption followed by
                                        purge-trap-desorb gas chromatography/
                                        mass spectrometry (P-T-D GC/MS). Much
                                        of the analytical method is described in
                                        EPA Method 624. Since the majority of
                                        gas streams sampled using the VOST will
                                        contain a high concentration of water, the
                                        P-T-D analytical method was chosen to
                                        minimize the effect of  water on the
                                        analytical system.
                                          A schematic diagram of the analytical
                                        system is shown  in Figure 2. Sorbenl
                                        cartridges are spiked with internal stand-
                                        ards and thermally desorbed into the P-T-
                                        D system by  heating to 180C for  1C
                                        minutes. Sample cartridges may be de-
                                        sorbed in pairs.  However, if the analyte
                                        concentrations  are anticipated  to  be
                                        sufficiently high to saturate the GC/MS

                                               Flow During
                                   Flow to
                                               Flow During
                                                               He or A/a
                                              Analytical Trap
                                              with Heating Coil
                                              (0.3 cm diameter
                                              by 25 cm long)

  r) 3%SP-2100(1 cm)

( 2) Tenax (7.7 cm)

(!}} Silica Gel(7.7 cm)

Cty Charcoal (7 7 cm)
Figure 2.    Schematic diagram of trap desorption/analysis system.
detector, when desorbed in pairs, con-
sideration should be given  to individual
analysis of cartridges. The desorbed
components pass into the bottom of the
water column, and are purged from the
analytical  trap into the GC/MS. The
volatile POHCs are separated by temper-
ature programmed gas chromatography
and  detected by low resolution mass
spectrometry. The quantities of volatile
POHCs collected on the sorbent cartridges
are calculated using the internal standard
  The sensitivity of the analytical method
for a particular POHC depends  on the 
level of interferences, the level of back-
ground contamination on blank sorbent
cartridges,  and the purgeability of the
POHCs from water. The target detection
limit for the method is 0.1/ug/m3 in stack
gas. This corresponds to 2 ng adsorbed on
a single pair of Tenax and Tenax/charcoal
cartridges.  The desorption of multiple
pairs of cartridges onto a single pair for
subsequent analysis may be required to
achieve the detection goal of 0.1/u g/m3.
Most uses of the VOST have not required
this level of detection.
                          F. M. Hansen is with Envirodyne Engineers. Inc., St. Louis, MO 63146.
                          Robin M. Anderson is the EPA Project Officer (see below).
                          The complete report, entitled "Protocol for the Collection and Analysis of Volatile
                            POHCs Using VOST." (Order No. PB  84-170 042; Cost: $10.00,  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:
                                 Industrial Environmental Research Laboratory
                                 U.S. Environmental Protection Agency
                                 Research Triangle Park, NC 27711

United States
Environmental Protection
Center for Environmental Research
Cincinnati OH 45268
   PERMIT No. G-3E
Official Business
Penalty for Private Use $300
                                                                                               r, II S. GOVERNMENT PRINTING OFFICE 759-01E