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Tracer Research Corporation <br /> f . <br /> particular, the sample size. If any component being analyzed was not detected, the <br /> detection limit for that compound in that analysis is given as a "less than" value (e. g. < 4.1 <br /> f <br /> ug/L). Detection limits obtained from GC analyses were calculated from the current <br /> response factor, the sample size, and the estimated minimum peak size (area) that would <br /> have been visible under the conditions of the measurement. <br /> QUALITY ASSURANCE/QUALITY CONTROL PROCEDURES <br /> Tracer Research Corporation's normal quality assurance procedures were followed <br /> in order to prevent any cross-contamination of soil gas samples. These procedures are <br /> described below: <br /> 1 I Steel probes are used only once during the day and then washed with high <br /> pressure soap and hot water spray or steam-cleaned to eliminate the possibility of <br /> cross-contamination. Enough probes are carried on each van to avoid the need to <br /> reuse any during the day. <br /> Probe adaptors (TRC's patented design) are used to connect the sample probe <br /> to the vacuum pump.The adaptor is designed to eliminate the possibility of exposing <br /> the sample stream to any part of the adaptor. Associated tubing connecting the <br /> adaptor to the vacuum pump is replaced periodically as needed during the job to <br /> insure cleanliness and good fit. At the end of each day the adaptor is cleaned with <br /> soap and water and baked in the GC oven. <br /> Silicone tubing (which acts as a septum for the syringe needle) is replaced as <br /> needed to insure proper sealing around the syringe needle. This tubing does not <br /> directly contact soil gas samples. <br /> Glass syringes are usually used for only one sample per day and are washed <br /> and baked out at night. If they must be used twice, they are purged with carrier gas <br /> f (nitrogen) and baked out between probe samplings. <br /> } 5 <br />