CONCLUSIONS - SR96

be held for a couple of days without altering the

posure for samples with a large surface/mass ra-

VOC concentration present (Turriff et al. 1995).

tio. Thus, soils obtained in small diameter coring

This sampling tool maintains the soil structure

devices should be extruded directly into appro-

during collection, storage and transfer as would a

priately prepared analysis vials. Sample vials that

plastic syringe; however, it is made out of either

do not contain a organic solvent before soil sample

stainless steel and proprietary composite material,

collection cannot have their hermetic seals broken

and uses Viton O-rings for hermetic seals. These

without incurring volatilization losses. To main-

materials are believed to rival that of the currently

tain site-representative VOC concentrations in soil

accepted VOA vial with regard to inertness and

samples, any collections and transfers for in-vial

preventing volatilization losses. In its current de-

analysis must occur rapidly with limited structure

sign, once an undistrubed soil core has been ob-

disruption and exposure.

tained by pushing the core barrel into an exposed

surface and removing it, a gas tight cap is used to

seal the opening. After estimating the concentra-

LITERATURE CITED

tion of VOC present for a colocated sample, the

soil can then be extruded after moving the cap

Barbeau, D.S., T.G. Ellis and C.P.L. Grady Jr.

from this temporary holding chamber, and trans-

(1995) Oxygen leakage during respirometric mea-

ferred directly into an appropriately prepared

surement: A caution on the use of PTFE tape. Wa-

VOA vial.

ter Research, 29(4): 12111212.

Another topic that this study addressed was

Chiou, C.T. and T.D. Shoup (1985) Soil sorption

sample size. Subsurface sample collection is both

of organic vapors and effects of humidity on sorp-

a very costly and time-consuming activity. Efforts

tive mechanism and capacity. Environmental Sci-

to minimize the impact of these two factors has

ence and Technology, 19: 11961200.

led to use of smaller and more rapid sampling sys-

Griffith, T.J., G.A. Robbins and T.M. Spittler

tems. The results of this study show that as the

(1988) A new method for field analysis of soils

surface area/mass ratio increases for intact soil

contaminated with aromatic hydrocarbon com-

cores, time of exposure needs to decrease in order

pounds. In FOCUS Conference on Eastern Regional

to maintain VOC concentrations representative of

Water Issues, National Water Well Association, Sep-

the in-situ conditions. When samples are retrieved

tember, Stamford, Connecticut, p. 223248.

from intact core liners or from recently excavated

Hewitt, A.D. (1995a) Determining volatile organic

pits, samples should be collected and transferred

compound concentration stability in soil. In Pro-

within a few minutes. However, if subsurface soils

ceedings of 11th annual Waste Testing and Quality As-

are retrieved in the barrel of a device with a diam-

surance Symposium, 2328 July, Washington, D.C.,

eter of less than 1.5 cm, and the soil has to be ex-

1995.

truded prior to subsampling, the subsequent col-

Hewitt, A.D. (1995b) Preservation of volatile or-

lection and transfer most likely cannot be per-

ganic compounds in soil subsamples. American

formed without substantial volatilization losses.

Environmental Laboratory, 1618 August.

In general, as the diameter and cohesiveness of the

Hewitt, A.D. (1995c) Enhanced preservation of

matrix decreases and vapor pressure of the analyte

volatile organic compounds in soil with sodium

increases, the ability to obtain samples that are

bisulfate. USA Cold Regions Research and Engi-

representative of the in-situ conditions diminishes.

neering Laboratory, Special Report 95-26.

Furthermore, with time playing such a critical vari-

Hewitt, A.D. and C.L Grant (1995) Round-robin

able for small diameter extruded soil cores, it be-

study of performance evaluation soils vapor-for-

comes unlikely that even sequentially collected

tified with volatile organic compounds. Environ-

colocated samples, would be representative of one

mental Science and Technology, 29: 769774.

another.

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 Laboratory,

CONCLUSIONS

JanuaryFebruary.

Soil samples retained in core liners covered with

Hewitt, A.D., P.H. Miyares and R.S. Sletten (1993)

either sheets of TFE-fluorocarbon or aluminum foil

Determination of two chlorinated volatile organic

are subject to volatilization losses. Uncontrollable

compounds in soil by headspace gas chromatrog-

volatilization losses occur within seconds of ex-

raphy and purge-and-trap gas chromatography