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' CORE LABORATORIES <br />~ ~/~/~ <br />Western Atlas <br />~riter~BtlDri9~ <br />ro... ~..w <br />1 Iri*i <br />ANALYTICAL CHEMISTRY DIVISION QUALITY ASSURANCE MANUAL <br />SOP N0. REVISION ND. EFFECTIVE DATE PAGE <br />HC-QAC-02 0 1!06192 73 of 104 <br /> li <br />l <br />S <br />S <br /> amp <br />p <br />t <br />es <br />' Split samples are separate homogenous aliquots of a sample taken from the <br /> same field site and submitted to two or more independent laboratories for <br /> analysis. <br /> <br /> Split samples measure the reproducibility (accuracy) of analysis. <br /> Performance Evaluation Samples <br /> QC Check Samples <br />' <br /> QC check samples are samples which contain target analyses at known <br />' concentrations. This type of quality control check Sample is often <br />submitted by clients and regulatory agencies as round robin or laboratory <br /> performance evaluation samples. Several QC check samlple programs are <br /> used by Core Laboratories as a quality assessment measure of laboratory <br />' performance (see sections 15.6 and 15.71. <br /> If the analyst is not informed of the true target analyte concentration value, <br />' the sample is referred to as a "blind" QC check sample. <br /> If the analyst is not informed that the sample is a quality control check <br />' sample, the sample is referred to as a "double blind" QC check sample. <br />' At a minimum, QC check samples should be analyzed on a quarterly basis. <br /> Blind Duplicates <br /> <br /> Blind duplicates are a measure of the repeatability within the laboratory. <br /> Blind duplicates are field samples which are split in the laboratory, logged <br />' in as two separate jobs and analyzed separately. Analysts are not, <br /> informed of the identity of blind duplicate samples which ire introduced. <br /> For homogenous samples, duplicate analyses should be wlthin 20% RPD <br />' (relative percent difference). <br />' 13.2 Inorganic Requirements <br />f General Quality Control Guidelines <br />