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6 <br /> jj� MEN in 1—cm <br /> .'i <br /> -rraGar Aosearch Corporation <br /> �A f <br /> QUALITY ASSURANCE/QUALITY CONTROL PROCEDURES <br /> Tracer Research Corporation's normal quality assurance procedures were (allowed <br /> in order to prevent any cross-contamination of soil gas samples. <br /> 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 <br /> Possibility for cross-contamination. Enough probes are carried on each van <br /> to avoid the need to reuse any during the day. <br /> Probe adaptors (steel reducer and tubing) are used once during the course <br /> of the day and cleaned at the end of the each working day by baking in the <br /> GC oven. The tubing is replaced periodically as needed during the job to <br /> insure cleanliness and good fit. <br /> Silicone tubing (connecting the adaptor to the vacuum pump; s replaced <br /> as needed to insure proper sealing around the syringe needle. This tubing <br /> does not directly contact soil gas samples. <br /> Polyethylene tubing used to collect water samples is used one then <br /> discarded to prevent cross contamination of water samples. <br /> k Glass sy,inges are usually used for only one sample per day and are <br /> washed and baked out at night. If they must be used twice, they are purged <br /> with carrier gas (nitrogen) and baked out between probe samplings. <br /> Septa through which soil gas samples are injected into the chromatograph <br /> are replaced on a daily basis to prevent possible gas leaks from the <br /> chromatographic column. <br /> Analytical instruments were calibrated each day by analytical standards <br /> from Chem Service, Inc. Calibration checks are also run after approximately <br /> - -------every five-sOil--as-sampling-locat ions, - <br /> 2 cc subsampling syringes are checked for contamination prior to sampling <br /> each day by injecting nitrogen carrier gas into the gas chromatograph. <br /> Prior to sampling each day, system blanks are run to check the sampling <br /> apparatus (probe, adaptor, 10 cc syringe) for contamination by drawing <br /> 5 <br />