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Woodward-Clyde Consultants <br /> II QUALITY CONTROL <br /> ------------------ <br /> A. PROJECT SPECIFIC QC. Spikes and duplicates were analyzed . <br /> ' at approximately• l0% of the sample load in order to establish <br /> I laboratory accuracy and precision. <br /> Precision is measured by using duplicate tests by Relative <br /> Percent Difference (RFD) as in: <br /> (sampleconcentration) _ (duplicateCsampleconcentration) <br /> RPD - - - _ - <br /> * 100 <br /> { mean concentration of sample and duplicate sample ) <br /> 1 <br /> Internal Accuracy (spike recovery) 'is measured by Percent <br /> ' Recovery ($REC) as in: <br /> ( spiked sample concentration <br /> ) ( sample concentration <br /> %REC --------------------------------- ---------- ) <br /> 100 <br /> ( true concentration of the spike ) <br /> ( See attached precision and accuracy summaries. ) <br /> ' B. METHOD PERFORMANCE. Precision and accuracy results were within <br /> EPA performance criteria for the method. <br /> C. METHOD BLANK RESULTS. A method blank_ is a jaboratory-generated <br /> sample which assesses the degree to which ;'laboratory operations <br /> ' and procedures cause false-positive analytical results for your <br /> samples. <br /> t In the method blanks associated wth these �sampies, target <br /> parameters were not detected at or above the practical quantitation <br /> limits noted on the data sheets in the Analytical Results Section. <br /> ' ( See attached reagent water data sheet in Section III. ) <br /> 1 <br /> ri <br /> A <br />