1992-04-01_REVISION - M1988112 - Laserfiche WebLink

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i , 1 1 LJ ~~~~~ CORE LABOF~IATORIES Western Atlas International io,o... v... iriTl c i ANALYTICAL CHEMISTRY DIVISION QUALITY ASSURANCE MIANUAL SOP N0. REVISION N0. EFFECTIVE OATE PAGE HC-QAC-02 0 1 /06192 73 of 104 Split Samples Split samples are separate homogenous aliquots of a sanhple taken from the same field site and submitted to two or more independent laboratories for analysis. Split samples measure the reproducibility (accuracy) of analysis. Performance Evaluation Samples QC Check Samples QC check samples are samples which contain target alnalytes at known concentrations. This type of quality control check sample is often submitted by clients and regulatory agencies as round robin or laboratory performance evaluation samples. Several QC check sample programs are used by Core Laboratories as a quality assessment measure of laboratory performance (see sections 15.6 and 15.71. tf the analyst is not informed of the true target analyte concentration value, the sample is referred to as a "blind" QC check sample. If the analyst is not informed that the sample is a quality control check) sample, the sample is referred to as a "double blind" QO check sample. At a minimum, QC check samples should be analyzed on'a quarterly basis. Blind Duplicates 1 1 Blind duplicates are a measure of the repeatability withih the laboratory. Blind duplicates are field samples which are split in the Igboratory, logged in as two separate jobs and analyzed separately. )Analysts are not informed of the identity of blind duplicate samples whichh are I iroduced. For homogenous samples, duplicate analyses should be wi In 20% RPD (relative percent difference). ~~_~~ 13.2 Inorganic Requirements General Quality Control Guidelines l~ ~ I awn vH Hn