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8020 / 5 6.0 Sample Collection, Preservation, and Handlin 6.1 Grab samples must be collected in glass containers (see Apparatus, Sections 4.1 and 4.2) having a total volume of at least 25 ml. Fill the sample bottles in such a manner that no air bubbles pass through the sample as the bottle is being filled. Seal the bottle so that no air bubbles are entrapped in it. Solid and semisolid samples are to be taken in the same way. Assure that no solid material interferes with sealing of the glass vial. Maintain the hermetic seal on the sample bottle until time of analysis. 6.2 Sample transfer implements: Implements are required to transfer portions of solid, semisolid, and liquid wastes from sample containers to laboratory glassware. The transfer must be accomplished rapidly to avoid loss of volatile components during the transfer step. Liquids may be trans- ferred using a hypodermic syringe with a wide -bore needle attached or with no needle. Solids may be transferred using a conventional laboratory spatula, spoon, or coring device. A coring device that is suitable for handling some samples can be made by using a glass tubing saw to cut away the enclosed end of the barrel of a glass hypodermic syringe. 6.3 The samples must be iced or refrigerated from the time of collec- tion until extraction. If the sample may contain free or combined chlorine, add sodium thiosulfate preservative (10 mg/40 ml will suffice for up to 5 ppm C12) to the empty sample bottles just prior to shipping to the sampling site, fill with sample just to overflowing, seal the bottle, and shake vigorously for 1 min. 6.4 Sample preservation: Non-sterile samples containing aromatic hydrocarbons cannot be stored longer than 4 hr because of biological degradation., Samples can be stabilized by adding free chlorine or by adjusting the pH to less than 2 with 1:1 hydrochloric acid. However, free chlorine will react with styrene and 2,3 -benzofuran. Therefore, if styrene or 2,3 -benzofuran are to be determined in chlorinated water, the sample must be dechlorinated with sodium thiosulfate at the rate of 1 mg/ppm of free chlorine. Once dechlorinated, the sample pH must be adjusted to less than 2 with 1:1 hydrochloric acid. If. chemical preservation is employed, the pre- servative is also added to the blanks. 6.5 All samples must be analyzed within 14 days of collection. 7.0 Procedures 7.1 The recommended gas chromatographic columns and operating conditions for the instrument are: Column 1: The carrier gas is helium at a flow rate of 30 ml/min. The temperature program sequences are as follows: for lower boiling compounds, operate at 50' C isothermal for 2 min, then program at 6' C/min to 90' C