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Tracer Research.Corporation if injections) in volumes ranging from 1 uL to 2 mL, depending on the VQC concentration at any particular location. i Sample probe vacuums ranged from 2-22 inches Hg. The maximum pump vacuum was measured at 240 inches Hg. , t ANALYTICAL PROCEDURES A Varian 3300 gas chromatograph was used for the soil gas analyses. It was equipped with a flame ionization detector (FID). Compounds were separated on a 6' by 4 1/8" OD packed column with OV-101 as the stationary phase in a temperature controlled oven. Nitrogen was used as the carrier gas. 1, Hydrocarbon compounds detected in the samples were identified by chromatographic retention time. Quantification of compounds was achieved by comparison of the detector response of the sample with the response measured for calibration standards (external standardization). Instrument calibration checks were run periodically throughout the day and system blanks were run at the beginning of the day to check for contamination in the soil gas sampling equipment. Air samples were also routinely analyzed to check for background levels in the atmosphere. Detection limits for the compounds of interest were a function of the injection volume as well as the detector sensitivity for individual compounds. Thus the detection limit varied with the sample size. Generally, the larger the injection size the greater the sensitivity. However, peaks for compounds of interest were kept within the linear range of the analytical equipment. If any compound had a high concentration, it was necessary to use small injections, and in some cases to dilute the sample to keep it within linear range. f This may have caused decreased detection limits for other compounds in the analyses. i The detection limits for the hydrocarbon compounds were approximately 0.03 ug/L. Detection limits were dependant upon the conditions of the measurement, in 4 I .