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CORE LABOFIATOgIES <br />~ '~///~ <br />' Western Atlas <br />International <br />,o... cae... <br />ANALYTICAL CHEMISTRY DIVISION QUALITY ASSURANCE MANUAL <br />SOP N0. REVISION N0. EFFECTIVE GATE PA6E <br />HC-QAC-02 0 1/06/92 68 of 104 <br />' Instrument blanks are normally analyzed once per analytical batch of <br />samples. <br />Method Blanks <br /> Method blanks are laboratory pure water samples whichh contain all of the <br /> method reagents which have been introduced into qhe field samples. <br /> Method blanks are taken through all of the same sample preparation and <br />' analysis steps as field samples. <br /> Method blanks measure the combined contamination frgm laboratory pure <br />water, method reagents, instrumentation, sample prepardtion, and analysis <br /> procedures. <br />' Measured analyte concentrations in method blanks should be less than the <br /> reported method detection limit. <br />' Method blanks are normally analyzed once per batch of simples or at a rate <br /> of 10% of the sample population, whichever is greater (i.ie., 1-10 samples, <br /> 1 blank; 11-20 samples, 2 blanks, etc.1. <br /> Reagent Blanks <br /> <br /> Reagent blanks are field samples containing all of the .method reagents <br /> except the color forming reagent. <br />1 ' <br />~ <br /> Reagent blank <br />s are used in certain colorimetric analyses to measure <br /> potential colorimetric interferences derived from the samlple matrix. <br />1 <br /> Instrument Carrvover Blank <br /> 4nstrument carryover blanks are laboratory pure water samples which are <br /> analyzed after ahigh-level sample. <br />' Carryover blanks measure the instrument contamination which may occur <br /> after analyzing highly concentrated samples. This type of blank is often <br /> used to decontaminate the instrument prior to continuing sample analysis. <br />' <br /> Standards <br /> <br />