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I ' GT ENVIRONMENTAL LABORATORY(GTEQ STANDARD OPERATING PROCEDURE ' CONCERNING FIELD PRESERVATION OF BTEX SAMPLES BY ACIDIFICATION SOP 12 ' If specifically prepared acidified vials are not available, apply the following Field Procedures, using the field acidification kit The kit contains. ' a) 500 cc b) dropping bottle of 50°16 hydrochloric acid or nitric acid ' c) narrow range pH paper, 10 - 2 5 pH range d) glass stirring rod ' 1 Collect approximately 300cc of water in beaker Try to minimize turbulence, bubbling, and time of exposure to the air I 2 For inorganic analysis use 50°16 nitric acid For volatile organic analysis use 50% hydrochloric ' acid Add 30 drops of 50°,6 acid to measuring cup Hold dropper completely vertically. lie 3 Gently mix with glass bar ' 4 Remove bar and touch wetted tip to the pH paper and check color code to assure it is below pH 2 As more acid is added the pH goes lower Discard used pH strip ' 5 Add more acid if necessary too much acid Is not a problem, just record how much was added (this will be helpful next time) Don't waste time trying to get it right-just add plenty of acid to ' get it below pH 2 Ideally, once you know how much acid needs to be added at one well, that amount will be sufficient for the rest. However, test the pH each time ' 6 Pour the water Into the vialsPar a ed for that well and cap off with no bubbles inside Again Pr ' turbulence and bubbling are to be minimized Also note that it Is Important that all of the vials for a given well be poured and sealed one right after another. Make sure the 300oc collected is enough to fill al of the vials with some to spare at the end The volume collected can be ' Increased but remember to proportionally increase the amount of acid added T. Acidification does not replace chilling Always chill samples and ship via air for next day delivery GROUNDWATER r_' TECHNOLOGY, INC