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f <br /> 5.0 QUALITY ASSURANCE/QUALITY CONTROL (QA/QC) EVALUATION <br /> I <br /> Laboratory and field QC sample results were evaluated to assess the quality of the <br /> individual sample results and overall method performance. Analytical performance was evaluated <br /> on a"batch QC" basis by evaluating the QC sample results for groups of samples that were <br /> prepared and analyzed together. The data evaluation performed included review of <br /> • Blanks (method, equipment, and trip); <br /> • Spikes (surrogate, laboratory control and matrix); <br /> • Duplicates (field, laboratory control and matrix); <br /> 4 • Comparability (Method 8010/8020 versus 8260), and <br /> • Sample Integrity (chain-of-custody documentation, sample preservation, <br /> and holding time compliance). <br /> The results of the data evaluation ar <br /> e summarized in the following subsections. <br /> 5.1 Blanks <br /> All reported results for p o the method blanks and equipment blanks are non-detect <br /> (less than the laboratory reporting limit) indicating no evidence of contamination from laboratory <br /> instrumentation and/or field equipment decontamination procedures. <br /> Four compounds (isopropylbenzene, n-propylbenzene, sec-butylbenzene, and <br /> naphthalene) were detected in the trip blank analyzed by U.S. EPA Method 8260 in excess of the <br /> reporting limit. Reanalysis of the trip blank by U.S. EPA Method 8260 gave comparable results. <br /> It should be noted that because only one trip blank was available for analysis, it is possible that the <br /> trip blank sample may have been contaminated by the autosampler probe when the sample was <br /> analyzed by U.S. EPA Method 8010/8020. The sample was analyzed by U.S. EPA Method 8260 <br /> after the U.S. EPA Method 8010/8020 analysis was performed. The concentration of naphthalene <br /> ® in the trip blank was 24 µg/L. The concentration of naphthalene in sample C007, which was <br /> 35275 Welty Road,Vernalis 13 March 1997 <br />