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Laboratory Control Sample <br /> Laboratory control samples (LCSs) are used to monitor the accuracy of the <br /> analytical procedure without the bias of a matrix. The LCS is prepared <br /> similarly to an MS sample, except a control (clean, reagent) matrix is <br /> utilized. The LCS recovery is calculated in the same way as the MS <br /> recovery. LCS recoveries will be compared to the laboratory established <br /> limits. LCSs with recoveries outside of acceptable limits should be <br /> reanalyzed along with each of the associated samples in the batch. If <br /> necessary, samples should be reextracted and reanalyzed. LCS samples <br /> will be prepared and performed by the laboratory at a frequency of one <br /> per batch of 20 samples. An LCS will be performed daily for each <br /> instrument that is used to perform volatile analyses. <br /> Laboratory Duplicate <br /> Laboratory duplicate samples are used to monitor and assess laboratory <br /> precision as well as potential matrix heterogeneity. Laboratory duplicate <br /> samples are performed by taking an additional aliquot of sample and <br /> analyzing it. Matrix spike duplicate (MSD) analyses will be performed for <br /> volatile analyses. The two results are compared and an RPD is calculated. <br /> The RPD is compared to the laboratory established limits. Because only <br /> soil samples will be submitted for analysis, no reanalysis of samples with <br /> elevated RPDs is required. A laboratory duplicate will be performed at a <br /> frequency of once per batch of 20 samples. <br /> Surrogate Spike <br /> Surrogate spikes are utilized to monitor potential interferences from the <br /> sample matrix. Surrogate spikes are required for organic analyses only. <br /> Known concentrations of surrogate spikes are added to each sample <br /> including QC samples prior to performing an organic analysis. The <br /> surrogate spike recovery is calculated similarly to the MS and LCS <br /> recovery. For this investigation the methods that utilize surrogates and <br /> either the method-specified or laboratory-generated limits will be used to <br /> monitor assess matrix interference with sample analyses. <br /> Samples with surrogate recoveries outside of acceptable limits should be <br /> reanalyzed and, when necessary, reextracted and reanalyzed. If surrogate <br /> recoveries are still outside of acceptable limits upon reextraction and <br /> reanalysis, the out-of-limit occurrence will be considered an indication of <br /> matrix interference. If the surrogate recoveries are within acceptable <br /> limits, then the reextraction and reanalysis will be reported. <br /> C-3 <br />