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.. GT ENVIRONMENTAL LABORATORY (GTEL) <br /> STANDARD OPERATING PROCEDURE <br /> CONCERNING FIELD PRESERVATION OF BTX SAMPLES <br /> BY ACIDIFICATION <br /> SAI' 22 <br /> Specially <br /> �. the followigpFieldeProcedures, using the fd 'vials are ieldvacidificationy <br /> .:it. The kit contains: <br /> a) 500 cc glass measuring cup or breaker. <br /> b) dropping bot,,ae of 50% hydrocloric acid or nitric <br /> acid. <br /> C) narrow range PH paper, 1.0-2.5 pH range. <br /> d) glass stirring rod. <br /> Collect approximately 300cc of water in bea.er. Try to <br /> miniir:ize turbulence, bubbling, and time of exposure to the <br /> air. <br /> 2• For inorganic analysis: use 50% nitric acid <br /> For volatile organic analysis: use 50% hydrocloric acid <br /> Add 30 drops of 50% acid to measurinc, cup. Hold dropper <br /> completely vertically, <br /> 3. Gently mix with glass bar. <br /> 4. Remove ba_ and touch wetted tip to the pH paper and check <br /> color code to assure it is below pH 2. As more acid is <br /> added the pH goes lower. Discard used pH strip. <br /> 5• Add more acid if neac,ssary. Too much acid is not a problem, <br /> Just record how much was added (this will be helpful next <br /> time) . Don't waste time trying to get it right - just add <br /> plenty of acid to get it below pH 2. Ideally, once you know <br /> R how much acid needs to be added at one well, that amount <br /> will be sufficient for the rest. However, test the pH each <br /> time. <br /> 6. Pour the water into the. vials <br /> preparedan <br /> off with no bubbles inside. Again turbulence aandebubblingap <br /> are to be minimized. Also note that it is important that <br /> all of the vials for a given well be poured and sealed one <br /> right after another. Make sure the 300cc collected is <br /> enough to fill all of the vials with some to spare at the <br /> end. The volume collected can be increased but remember to <br /> Proportionally increase the amount of acid added. <br /> 7. Acidification does not replace chilling. Always chill <br /> samples and ship via air for next day delivery. <br /> w <br />