VOLATILE ORGANIC COMPOUNDS IN SOILS AND

SUMMARY OF METHOD 2.1 At least 2 g of a soil sample are placed into a crimp-seal or screw-top glass headspace vial at time of sampling. 2.2 A matrix modifying solution is added to each soil sample to act as a chemical preservative. In addition, each sample is fortified with internal standards and surrogate compounds. These additions may be done either in the field or in the laboratory upon receipt of samples. 2.3 Additional sample volume is collected in a VOA vial for dry weight determination and for high concentration determination if the sample concentration requires it. 2.4 In the laboratory, the vials are rotated to allow for diffusion of the internal standards and surrogates throughout the matrix. The vials are placed in the autosampler carousel of the headspace analyzer and maintained at room temperature. Approximately 1 hour prior to analysis, the individual vials are moved to a heated zone and allowed to equilibrate. The sample is then mixed by mechanical vibration while the elevated temperature is maintained. 2.5 The autosampler then pressurizes the vial with helium which forces a portion of the headspace gas mixture through a heated transfer line onto the GC column. 2.6 Determinative analysis is performed using the appropriate GC or GC/MS method.