Laserfiche WebLink
0 <br />often cost effective in the long term and ensure data <br />reliability relative to cross -contamination. If transfer of <br />equipment is necessary, sampling should proceed from the <br />least contaminated to the most contaminated well, if the <br />latter information is available before sample collection. <br />Water samples should be collected in vials or containers <br />specifically designed to, prevent loss of volatile constitu- <br />ents from the sample. These vials should be provided by an <br />analytical laboratory, and preferably, the laboratory <br />conducting the analysis. No headspace should be present in <br />the sample container once the container has been capped. <br />This can be checked by inverting the bottle, once the sample <br />is collected, and looking for bubbles. Sometimes it is not <br />possible to collect a sample without air bubbles, particu- <br />larly if water is aerated. In these cases, the investigator <br />should record the problem and account for probable error. <br />Cooling samples may also produce headspace (bubbles), but <br />these will disappear once the sample is warmed for analysis. <br />Samples should be placed in an ice chest maintained at 40C <br />with blue ice (care should be taken to prevent freezing of <br />the water and bursting of the glass vial). A thermometer <br />with a protected bulb should be carried in each ice chest_ <br />c. Surface water: Grab samples should be collected in appro- <br />priate glass containers supplied by the laboratory. The <br />sample should be collected in such a manner that air bubbles <br />are not entrapped. Semisolid samples should be collected <br />the same way. The collected samples should be refrigerated <br />(blue ice, 40C) for transport and analyzed within 7 days of <br />collection (14 days with preservatives). <br />-62- <br />