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performing any task associated with the analysis of samples. The SOP <br /> will describe step-by-step procedures to perform a specific task. SOPS will <br /> be utilized to ensure acceptable precision and quality. <br /> Laboratory quality control samples will include the use of method blanks, <br /> matrix spikes, laboratory control samples, laboratory duplicates and <br /> surrogate spikes. The results of QC samples will be reported with the <br /> associated project sample results. <br /> Method Blank <br /> Method blanks are used to monitor and ensure the analytical system is <br /> free of contamination due to either carryover from previous samples or <br /> from laboratory procedures. A method blank is prepared using <br /> laboratory reagent water. The reagent matrix is extracted and analyzed as <br /> a sample by the laboratory. A method blank should be performed at least <br /> once per day for each matrix and method utilized by the laboratory for <br /> that day. A maximum of 20 samples should be associated with a method <br /> blank. Target analytes should not be present at levels above the practical <br /> quantitation limit (PQL); compounds identified by USEPA as common <br /> laboratory contaminants should not be present at concentrations greater <br /> than three times the detection limit. Project samples that are associated <br /> with blanks that do not meet these criteria and exhibit detections of the <br /> blank contaminant will be reanalyzed and, if necessarv, reextracted and <br /> reanalyzed. Samples for which no analysis meeting these criteria is <br /> attained may be resampled and reanalyzed. <br /> Matrix Spike <br /> Matrix spike (MS) samples are utilized to monitor and assess the effects of <br /> the sample matrix on the sample analysis and as a check on the accuracy <br /> of the analysis. MS samples are prepared by adding known quantities of <br /> target compounds to a sample. The results of the analysis are compared <br /> with the known concentrations added to the sample, and a MS recovery is <br /> calculated. The calculated recovery gives an evaluation of the effect of the <br /> sample matrix and accuracy of the analysis procedure. MS recoveries will <br /> be compared to the laboratory established limits. No corrective action or <br /> reanalysis of samples is required for MS recoveries outside of acceptable <br /> limits. MS samples will be prepared and performed by the laboratory at a <br /> frequency of one per batch of 20 samples. An MS will be performed daily <br /> for each instrument that is used to perform volatile analyses. <br /> C-2 <br />