Obtaining and Transferring Soils for
In-Vial Analysis of Volatile Organic Compounds
ALAN D. HEWITT AND NICOLE J.E. LUKASH
5035, attention must also be given to how the
INTRODUCTION
sample is obtained and transferred prior to this
An in-vial method of preparing and analyzing
treatment. The necessity to limit disruption and
soils for volatile organic compounds (VOCs) re-
exposure of the unsaturated soil sample, while it
quires soil to be transferred directly to a vessel with
is being transferred to an analysis vial, is impera-
hermetic seals. This approach differs from those
tive because the analytes of concern have high va-
often used under the guidelines of Method 5030
por pressures, allowing them to either partly or
of the SW-846 (U.S. EPA 1986) by using only a
largely exist as gases under environmental condi-
single transfer process and a vessel that is com-
tions. For instance, to avoid the volatilization losses
patible with the instrumentation on which the
incurred by using utensils that allow the soil to
analysis will be performed. In-vial soil sample
randomly fracture and expose an uncontrolled
preparation and analysis methods address much
amount of surface area (stainless steel spoons,
of the past criticism regarding the volatilization
spatulas, garden trowels, etc.), small coring tools
losses of VOCs caused by repeated exposures and
have been used. Examples of such devices are com-
uncontrolled disturbance of soil samples when
mon laboratory plastic syringes with their tips re-
transferred to and from receptacles of various
moved (Griffith et al. 1988) and specially designed
shapes and sizes (Urban et al. 1989, Seigrist and
stainless steel samplers (Associated Design and
Jenssen 1990, Hewitt et al. 1993, Illias 1993, Voice
Manufacturing Co., EN CHEM, Inc.). The use of
and Kolb 1993, Lewis et al. 1994).
these coring tools is addressed in the current draft
The U.S. Environmental Protection Agency has
of Method 5021, and the inclusion of these devices
proposed Methods 5021 and 5035, two in-vial
is anticipated for the final version of Method 5035.
preparation and analysis procedures for the third
The merit of using a limited-disruption single-
update of the Test Methods for Evaluating Solid
transfer and in-vial approach to soil sample col-
Waste, SW-846. The first is designed for low level
lection, handling and analysis is to achieve more
(<1-g VOC/g) analysis by purge-and-trap, gas
representative estimates of the in-situ environ-
chromatography/mass spectrometry (Method
mental VOC concentrations than possible using
8240 or 8260). The second is an equilibrium
previous approaches.
headspace (HS) approach to analysis that can be
The purpose of this study is to look closely at
used in conjunction with Methods 8015, 8021, or
some collection and transfer procedures that may
8260. Both of these of methods use volatile organic
be used with in-vial methods of analysis. Experi-
analysis (VOA) vials (22 and 44 mL), which rely
ments were designed to assess if VOC concentra-
on a Teflon-faced septum with bonded silicon or
tions are maintained in an intact soil sample when
rubber backing, compressed by a rigid plastic or
1) held for less than an hour in a metal core liner,
aluminum cap, to form a hermetic seal with a glass
2) held for days in a metal core liner sealed with
rim. This septum also forms a vapor-tight seal
TFEflourocarbon sheets or aluminum foil (ASTM
around the needles used to remove VOCs from the
D4547-91), 3) held for less than 2 minutes in a plas-
vial during sample analysis.
tic bag after extruding from a sampling device,
In addition to using the in-vial preparation and
and 4) immediately transferred to an empty vial
analysis methods described in Methods 5021 and
to which a solvent was added later.
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