organic compounds in aged soils. Analytical
This feasibility study only considered field
Chemistry, 68: 34313433.
samples contaminated with TCE. However, other
compounds would be expected to behave simi-
Conant, B.H., R.W. Gillham, and C.A. Mendoza
larly, since the response of PIDs varies by less
(1996) Vapor transport of trichloroethylene in the
than a factor of 1.4 for many common chlorinated
unsaturated zone: Field and numerical modeling
and aromatic hydrocarbons (i.e., TCE, tetra-
investigations. Water Resources Research, 32: 922.
chloroethene, benzene, and toluene). Further-
Fitzgerald, J. (1989) On site analytical screening of
more, it is possible that this on-site rapid analysis
gasoline contaminated media using a jar head-
method would also work for fuels heavier than
space procedure. In Petroleum Contaminated Soil.
gasoline, although the reduction of highly vola-
Chesea, Michigan: Lewis Publishers, vol. 2, p.
tile constituents may require larger quantities
(≈50 g) of soil. We encourage regulators and site
Hewitt, A.D. (1994) Comparison of methods for
investigators to incorporate this on-site system-
sampling vadose zone soils for the determination
atic and rapid approach to soil vapor analysis, so
of trichloroethylene. Journal of the Association of Of-
that informed decisions about how to handle and
ficial Analytical Chemists, 77(2): 458463.
prepare samples for VOC analysis can be made.
Hewitt, A.D. (1995) Evaluation of methanol and
To assist in the documentation of a standard
NaHSO4 for preservation of volatile organic com-
operational procedure, a general outline of this
pounds in soil subsamples. American Environmen-
method is provided in Appendix A.
tal Lab, August.
Hewitt, A.D. (1996a) Establishing a relationship
between passive soil vapor and grab sample tech-
niques for determining volatile organic com-
pounds. USA Cold Regions Research and Engi-
In general, low-concentration-level methods
neering Laboratory, Special Report 96-14.
are practical when we attempt to establish the full
Hewitt, A.D. (1996b) Methods of preparing soil
spatial extent of the impact of a spill or leak of
VOCs into the vadose zone. However, when the
samples for headspace analysis of volatile organic
main objective of a site investigation is to locate
compounds: Emphasis on salting out. In Proceed-
and remediate source regions, where residual
ings of 12th annual Waste Testing and Quality Assur-
product often exists, methods that maintain the
ance Symposium, 2326 July, Washington, D.C., p.
representiveness of high levels of VOC concentra-
tions (>0.2 mg/kg) in soil samples are of para-
Hewitt, A.D. (1997) Preparing soil samples for vol-
mount concern. Failure to maintain representa-
atile organic compound analysis. USA Cold Re-
tive VOC concentrations results in false negative
gions Research and Engineering Laboratory, Spe-
levels and often prolongs the investigation stage,
cial Report 97-11.
and can lead to inadequate remediation, and pos-
Hewitt, A.D., and N.J.E. Lukash (1996) Obtaining
sibly even a premature site closure. To address
and transferring soils for in-vial analysis of vola-
these shortfalls, we recommend estimating the
tile organic compounds. USA Cold Regions Re-
total VOC concentration at a sampling location
search and Engineering Laboratory, Special Re-
before collecting samples for accurate quantita-
Hewitt, A.D., and S.A. Shoop (1994) Rapid assess-
tion. The approach described here was success-
ment of trichloroethylene in ground water.
fully applied during two field trials at a site con-
taminated with TCE, and should also be effective
Ground Water Monitoring and Remediadion, 3: 116
for most other halogenated and aromatic com-
pounds, including petroleum products. This
Hewitt, A.D., P.H. Miyares, D.C. Leggett, and T.F.
method will tell site investigators when the use of
Jenkins (1992) Comparison of analytical methods
MeOH is justified for on-site sample preparation
for determination of volatile organic compounds.
by indicating when VOC concentrations exceed
Environmental Science and Technology, 26: 1932
Hewitt, A.D., T.F. Jenkins, and C.L. Grant (1995)
Collection, handling, and storage: Keys to im-
proved data quality for volatile organic com-
pounds in soil. American Environmental Lab, Janu-
Askari, M.D.F., M.P. Maskarinec, S.M. Smith, P.M.
Beam, and C.C. Travis (1996) Effectiveness of
purge-and-trap for measurement of volatile
Illias, A.M., and C. Jaeger (1993) Evaluation of