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PMR <br /> bond <br /> 3. Laboratory Method Blank Analyses <br /> Method blanks are prepared from a purified matrix and analyzed with investigative samples to determine the <br /> existence and magnitude of sample contamination introduced during the analytical procedures. <br /> For this study, laboratory method blanks were analyzed at a minimum frequency of 1 per 20 investigative <br /> samples and/or 1 per analytical batch. <br /> All method blank results were non-detect, indicating that laboratory contamination was not a factor for this <br /> investigation. <br /> 4. Surrogate Spike Recoveries <br /> In accordance with the method employed, all samples, blanks, and QC samples analyzed for organics are <br /> spiked with surrogate compounds prior to sample extraction. Surrogate recoveries provide a means to <br /> evaluate the effects of laboratory performance on individual sample matrices. Due to necessary sample <br /> dilutions, surrogate recoveries were not assessed for some samples. <br /> All samples submitted for diesel range organics (DRO)/motor oil range organics (ORO) analysis were spiked <br /> with the appropriate number of surrogate compounds prior to sample extraction. <br /> Surrogate recoveries were assessed against the control limits. All surrogate recoveries met the associated <br /> criteria. <br /> 5. Laboratory Control Sample Analyses <br /> Laboratory control samples (LCS) are prepared and analyzed as samples to assess the analytical <br /> efficiencies of the method employed, independent of sample matrix effects. <br /> For this study, LCS were analyzed at a minimum frequency of 1 per 20 investigative samples and/or 1 per <br /> analytical batch. <br /> The LCS contained all analytes of interest. All LCS recoveries were within associated control limits, <br /> demonstrating acceptable analytical accuracy. <br /> 6. Matrix Spike/Matrix Spike Duplicate Analyses <br /> To evaluate the effects of sample matrices on the preparation process, measurement procedures, and <br /> accuracy of a particular analysis, samples are spiked with a known concentration of the analyte of concern <br /> and analyzed as matrix spike/matrix spike duplicate(MS/MSD) samples. The RPD between the MS and <br /> MSD is used to assess analytical precision. MS/MSD analyses were performed as specified in Table 1. <br /> The original sample concentrations were significantly greater than the spike concentrations and the <br /> recoveries were not assessed. <br /> GHD 11183954Memo-678.docx 2 <br />