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% <br /> MMA ` C <br /> Ml <br /> Tracer Reeeareis Corporation <br />�i I <br /> injections) in volumes ranging from 1 uL to 2 ml,depending on the VOC concentration at <br /> any particalar location. <br /> Sample probe vacuums ranged from 2-22 inches Hg. The maximum pump vacuum <br /> A as measured at 240 inches Hg. <br /> F <br /> 1 <br /> ANALYTICAL PROCEDURES <br /> A Varian 3300 gas chromatograph wzs used for the soil gas analyses. It was <br /> equipped with a fame ionization detector (FID). Compounds were separated on a 6' by <br /> 1/8" OD packed column with OV-101 as the stationary phase in a temperature controlled <br /> oven. Nitrogen was used as the carrier gas. <br /> Hydrocarbon compounds detected in the samples were identified by chromatographic <br /> retention time. Quantification of compounds was achieved by comparison of the detector <br />` response of the sample with the response measured for calibration standards (external <br /> standardization). Instrument calibration checks were run periodically throughout the day ; <br /> and system blanks were run at th..e beginning of thL day to check for contamination in the <br /> soil gas sampling equipment. .fir samples were also routinely analyzed to check for � <br /> i <br /> background levels in the atmosphere. ' <br /> Detection limits for the compounds of interest were a function of the injection <br /> volume as well as the detector sensitivity for individual compounds. Thus the detection limit <br /> varied with the sample size. Generally, the larger the injection size the greater the <br /> sensitivity. However,peaks for compounds of interest were kept within the linear range of <br /> the analytical equipment. If any compound had a high concentration, it was necessary to <br /> use small injections, and in some cases to dilute the sample to keep it within linear range. <br /> This may have caused decreased detection limits for other compounds in the analyses. <br /> The detection limits for the hydrocarbon compounds wereapproximately 0.03 <br /> ug/L. Detection limits were dependant upon the conditions of the measurement, in <br /> 4 <br /> aiwn�n�nrn•vnnnu� - � �wx rrxsxeumnrr ��{®®ITAa��solsounr�== <br />