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' GT ENVIRONMENTAL LABORATORY (GTEL) <br /> STANDARD OPERATING PROCEDURE <br /> CONCERNING FIELD PRESERVATION OF BTEX SAMPLES BY ACIDIFICATION <br /> SOP 12 <br />' If specifically prepared acidified vials are not available, apply the following Field Procedures, using <br />' the field acidification kit The kit contains <br /> a) 500 cc <br />' b) dropping bottle of 50% hydrochloric acid or nitric acid <br /> c) narrow range pH paper, 10 - 2 5 pH range <br /> d) glass stirring rod <br />' 1 Collect approximately 300cc of water In beaker Try to minimize turbulence, bubbling, and <br /> time of exposure to the air <br />' 2 For inorganic analysis use 50% nitric acid For volatile organic analysis use 50% <br /> hydrochloric acid Add 30 drops of 50% acid to measuring cup Hold dropper completely <br /> vertically <br /> 3 Gently mix with glass bar <br />' 4 Remove bar and touch wetted tip P to the H paper and check color code to assure it is below <br />' pH 2 As more acid is added the pH goes lower Discard used pH strip <br />' 5 Add more acid If necessary too much acid is not a problem, just record how much was <br /> added (this will be helpful next time) Don't waste time trying to get It right -Just add plenty of <br /> acid to get it below pH 2 Ideally, once you know how much acid needs to be added at one <br />' well, that amount will be sufficient for the rest However, test the pH each time <br /> 1 <br /> SOP 12 Page 1 of 2 <br /> GROUNDWATER <br /> TECHNOLOGY, INC <br />