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Emec0 <br /> Si le C rol Sam le. An SCS consists of a control matrix that <br /> is spiked with surrogate compounds appropriate to the method being <br /> used. In cases where no surrogate is available, (e.g. metals or <br /> conventional analyses) a single control sample identical to the <br /> DGS serves as the control sample. An SCS is prepared for each <br /> sample lot. Accuracy is calculated identically to the DCS. The <br /> SCS results associated with your samples are on the attached <br /> Single Control Sample Report. <br /> Accuracy is measured by Percent Recovery as in: <br /> % recovery = ,tmeasurPd concentratia x 100 <br /> (actual concentration) <br /> Precision is measured using duplicate tests by Relative Percent Difference <br /> (RpD) as in: <br /> RpD % recovery test I - % recover 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 ioata, EPA sor ry limits are set, with the <br /> approval of theQuality Assurancedepartment. <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, unless the method requires or the client requests that <br /> such correction be made. <br /> Results are on the attached data sheets. <br />