Received for review July 30, 1998

Revised manuscript received February 11, 1999

Accepted February 18, 1999

Abstract:

A mixture of volatile organic compounds (VOCs) was encapsulated and mixed with a soil to produce a product suitable for use as a double blind source of VOCs in a soil performance evaluation sample. Two independent laboratories analyzed the standard encapsulated VOC/soil mixture for benzene, toluene, ethylbenzene, and xylene by using U.S. EPA SW-846 Method 5035 in conjunction with SW-846 Method 8020. One laboratory received the sample as a single blind standard, while the other laboratory received the sample as a double blind standard. The percent relative standard deviation (%RSD) for triplicate analyses ranged from 2 to 13%. The lowest %RSD was for m/p-xylene (2%) from the sample analyzed as a double blind sample. Analytical results from these pilot studies indicate that it is possible to prepare standard soil samples contaminated with known amounts of VOCs which will enable soil samples to be submitted to environmental analytical laboratories as a truly blind sample.