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• QUALITY CONTROL REPORT <br /> METHOD BLANK PESULTS A mathod blank (MB) is a laboratory generated sample free <br /> of any contamination The method blank assesses the degree to which the <br /> laboratory operations and procedures cause false-positive analytical results for <br /> your samples The method blank results associated with your samples are <br /> attached <br /> LABORATORY CONTROL SPIKES <br /> The LCS Program <br /> The laboratory control spike is a well characterized matrix (organic pure <br /> type II for water samples and contamination free sand for soil samples) <br /> which is spiked with certain target parameters and analyzed in duplicate <br /> at approximately 108 of the sample load in order to assure the accuracy <br /> and precision of the analytical method. The results of the laboratory <br /> control spike associated with your samples are. attached <br /> Accuracy is measured using percent recovery, i e <br /> (measured concentration) <br /> Percent Recovery — ------------------------ x 100 <br /> (actual concentration) <br /> Precision is measured using the relative percent difference (RPU) from <br /> duplicate tests, i e <br /> % Recovery of Spike(4) - 8 Recovery of Spike <br /> RPD — ---------------------------------------------------- x 100 <br /> (8 Recovery of Spike(l) + 8 Recovery of Spike,Z) )/2 <br /> Control limits for accuracy and precision are different fol different <br /> methods They may also vary with the different sample matrices They are <br /> based on laboratory average historical data and EPA limits which are <br /> approved by the Quality Assurance Department McLaren Analytical <br /> Laboratory reanalyzes samples if the precision or accuracy is out of <br /> acceptance control limits <br /> Zz- <br /> McLaren <br /> �" (DC3-CN2612) <br />