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CORE LABORATORIES <br />~ ~1~/~ <br />' Western Aelas <br />International <br />.a o.... ra.,., <br />' T I T I F <br />ANALYTICAL CHEMISTRY DIVISION QUALITY ASSURANCE MANUAL <br />SOP ND. AEVIS ION N0. EFFECTIVE DATE PAGH <br />HC-QAC-02 0 1/06/92 72 of 10< <br />' <br /> Field sample spikes are samples which have been spiked with known <br /> amounts of target analytes in the field prior to shipment to the laboratory. <br /> " <br />" <br /> Field sample spikes are often submitted by clients as <br />double blind <br />quality <br /> control samples to measure the recovery of target analytes for both field <br /> and laboratory procedures. <br /> Duplicates <br /> <br /> Duplicates are analyzed in order to measure the precision of analyses. For <br />' homogenous samples, duplicate analyses should be within 20% RPD (relative <br />percent difference) <br /> . <br /> Laboratory Duplicates <br /> Laboratory duplicates are two separate sample aliquots taken from the <br /> same field sample. <br /> Laboratory duplicates are used as a cumulative measure of laboratory <br />' analytical precision and non-homogenous sample matrix eflfects. <br /> Laboratory duplicates should be analyzed once per batch of samples or at <br /> a rate of 10% of the sample population, whichever is greater (sample <br /> volumes permitting). <br /> Laboratory Replicates <br /> Laboratory replicates are repeated analyses of a single field sample aliquot. ~ <br /> I <br /> Laboratory replicates measure the precision (repeatability) of sample <br /> analyses. <br />' <br /> Field Duplicates <br />' Field duplicates are duplicate field samples which are collected in a separate <br /> container under identical field sampling conditions. <br />Field duplicates are often submitted by clients in order to measure the <br />precision of both field and laboratory procedure. <br />i <br />t 1 <br />I <br />