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2 / ORGANIC ANALYTICAL METHODS - GC syringe or purging device must be rinsed out between samples with reagent water. Whenever an unusually concentrated sample is encountered, it should be followed by an analysis of reagent water to check for cross contamination. For samples containing large amounts of water-soluble materials, suspended solids, high boiling compounds or high levels of volatile organics, it may be necessary to wash out the syringe or purging device with a detergent solution, rinse it with distilled water, and then dry it in a 105' C oven between analyses. 3.3 Before processing any samples, the analyst should demonstrate daily through the analysis of an organic -free water or solvent blank that the entire analytical system is interference -free. Standard quality assurance practices should be used with this method. Field replicates should be collected to validate the precision of the sampling technique. Laboratory replicates should be analyzed to validate the precision of the analysis. Fortified samples should be analyzed to validate the accuracy of the anal- yses. Where doubt exists over the identification of a peak on the gas chromatogram, confirmatory techniques such as mass: spectroscopy should be used. 3.4 The analyst should maintain constant surveillance of both the performance of the analytical system and the effectiveness of the method in dealing with each sample matrix. This is done by spiking each waste sample with known amounts of the compounds that the waste is being analyzed for. Using these spiked waste samples, the sensitivity of the instrument is then readjusted so that 1 µg/g of sample can be readily detected. Detection 'imits necessary for groundwater monitoring are much lower. The analyst should adjust instrument sensitivity according to Table 1 (below) when analyzing groundwater samples. 4.0 Apparatus and Materials 4.1 Vial with cap: 40-m1 capacity equivalent). Detergent wash, rinse with and dry at 105' C before use. screw cap vial (Pierce #13075 or tap and distilled deionized water, 4.2 Septum: Teflon -faced silicone (Pierce #12722 or equivalent). Detergent wash, rinse with tap and distilled deionized water, and dry at 105' C for 30 min before use. NOTE: Do not heat the TFE seals for extended periods of time (i.e., more than 1 hour) because the silicone layer slowly degrades at 105' C. 4.3 Sample introduction apparatus for Methods 5020 and 5030. 4.4 Gas chromatograph: Analytical system complete with programmable gas chromatograph suitable for on -column injection or purge -and -trap sample introduction and all required accessories, including PID, column supplies, recorder, and gases. A data system for measuring peak area is recommended.