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Ground Water Sampling <br /> for holding samples that will be analyzed for metals, Cal/EPA recommends the <br /> • use of glass containers instead There is evidence that metals may sorb into the <br /> polyethylene matrix and that the acid preservative may fail to desorb them When <br /> organics are the analytes of interest, glass bottles with Teflon-lined caps should be <br /> used The SAP should refer to the specific analytical method that designates an <br /> acceptable container <br /> New containers should be prepared based on the analyte of interest, used <br /> containers are to be discarded The cleaning procedures used for sample <br /> containers are the same as those discussed in Section 2.3 6 The cleanliness of a <br /> batch of precleaned bottles should be verified in the laboratory The residue <br /> analysis should be available prior to sampling in the field <br /> 252 Sample Preservation <br /> The SAP should identify the sample preservation methods that will be used <br /> Methods of sample preservation are relatively limited, and are generally intended <br /> to 1) retard biological action, 2)retard chemical reactions such as hydrolysis or <br /> oxidation, and 3) reduce sorption effects Preservation methods are generally <br /> limited to pH control,chemical addition, refrigeration, and protection from light <br /> Most sample containers provided by a laboratory have pre-added preservative <br /> If these are not available, then preservatives should be added in the field No <br /> sample should be brought back to the laboratory for preservation For pH control, <br /> test strips should be used to verify that samples have attained the appropriate pH <br /> range for sample preservation <br /> Most commercial shipping containers ("coolers") leak when the interior water <br />' level reaches the lid-body interface As a result, the carner may refuse to ship the <br /> container For this reason, Cal/EPA recommends that two polyethylene overpack <br /> bags be used in shipping The firs twill contain the sample bottles, the second the <br /> ice needed to keep the samples at 4°C If the bags are taped shut, the melt water <br /> will not reach the bottle labels or escape from the cooler This precaution may not <br /> be necessary if "blue" ice or other contained coolants are used Glass containers <br />' should be protected from breakage using bubble wrap and/or vermiculite The <br /> vermiculite will also absorb any spills or melted ice <br /> As specified by U S EPA (1986),a temperature history of the samples should be <br /> maintained as a quality control measure This is done by recording the <br /> temperature on the chain-of-custody record (Section 2 6) before the sample <br /> containers are sealed for shipment Upon receipt of the shipment,the laboratory <br /> is required to record the temperature at receipt on the chain-of-custody record <br /> Holding time refers to the period that begins when the sample is collected from the <br />' well and ends with its extraction or analysis Holding time is not measured from <br /> the time the laboratory receives the samples Any laboratory submission to <br /> Cal/EPA should contain the date/time sampled, the date/time received, the <br /> date/t im e extracted, and the date/t tme analyzed <br /> 21 <br />