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Accuracy is measured by Percent Recovery as in: <br />% recovery = (measured concentration) x 100 <br />(actual concentration) <br />Precision is measured using duplicate tests by Relative Percent Difference <br />(RPD) as in: <br />RPD = (% recovery test 1 - % recovery test 2) x 100 <br />(% recovery test 1 + % recovery test 2)/2 <br />Control limits for accuracy (percent recovery) are based on the average, <br />historical percent recovery +/-3 standard deviation units. Control limits <br />for precision (relative percent difference) range from 0 (identical <br />duplicate DCS results) to the average, historical relative percent <br />difference + 3 standard deviation units. In cases where there is not <br />enough historical data, EPA limits or advisory limits are set, with the <br />approval of the Quality Assurance department. <br />IV Analysis Results <br />Test methods may include minor modifications of published EPA Methods such <br />as reporting limits or parameter lists. Reporting limits are adjusted to <br />reflect dilution of the sample, when appropriate. Solid and waste samples <br />are reported on an "as received" basis; i.e., no correction is made for <br />moisture content. All data is "blank corrected" by subtracting the level <br />of contamination, if any, found in the laboratory method blank from the <br />analytical result before it is reported. <br />Results are on the attached data sheets. <br />E <br />Enseco <br />