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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 10% of the sample load in order to establish <br /> laboratory accuracy and precision. <br /> Precision is measured by using duplicate tests by Relative <br /> Percent Difference (RPD) as in: <br /> (sample concentration) - (duplicate sample concentration) <br /> RPD - <br /> ------------------------------..--------------------------- * 140 <br /> ( mean concentration of sample and duplicate sample ) <br /> Internal Accuracy (spike recovery) is measured by Percent <br /> Recovery (%REC) as in: <br /> ( spiked sample concentration ) - ( sample concentration ) <br /> %REC = ---------------------------------------------------------- * 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 laboratory-generated <br /> sample which assesses the degree to which laboratorprations <br />' and procedures cause false-positive analytical results for your <br /> samples. <br />' In the method blanks associated wth these samples, 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 />