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CORE LABORATORIES <br />~ ~/~s~ <br />' Western Atlas <br />International <br />TITI F _.._ <br />ANALYTICAL CHEMISTRY DIVISION QUALITY ASSURANCE MANUAL ~ <br />SOP N0. REVISION N0. EFFECTIVE DATE PAGiE <br />HC-QAC-02 0 1!06!92 <br />1 <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 />' Field sample spikes are often submitted by clients as double blind" ality <br /> control samples to measure the recovery of targ~t-anal tes 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 ~0% RPD (relative <br /> percent difference). <br />t 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 @ffects. <br /> Laboratory duplicates should be analyzed once per batch Hof samples or atj <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 />' <br /> Laboratory replicates measure the precision (repeatabillity) of sample <br /> analyses. <br /> <br /> Field Duplicates <br />' Field duplicates are duplicate field samples which are collec>Jed in a separate <br /> container under identical field sampling conditions. <br />' Field duplicates are often submitted by clients in order to measure the <br /> <br />I precision of both field and laboratory procedure. <br /> <br />I <br />I <br /> <br />