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CORE LABORATORIES <br />~ fO/~, <br />' Western Aclas <br />International <br />e.~o...-w~.y. <br />T1Tl F <br />ANALYTICAL CHEMISTRY DIVISION QUALITY ASSURANCE MANUAL <br />SOP ND. REVISION N0. EFFECTIVE DATE PAGE <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 /> i <br />i <br />" <br />" <br /> Field sample spikes are often submitted by cl <br />ents as <br />double bl <br />nd <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 />' Laboratorv 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 effects. <br /> Laboratory duplicates should be analyzed once per batch oaf samples or at <br /> a rate of 10% of the sample population, whichever is greater (sample <br />' volumes permitting). <br /> Laboratorv Replicates <br /> Laboratory replicates are repeated analyses of a single field sample aliquot. <br /> l <br /> Laboratory replicates measure the precision (repeatabi{ity) of samp <br />e <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 /> <br />i precision of both field and laboratory procedure. <br /> <br />I <br />1 <br />I <br /> <br />