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' SOP TO-14A/15 <br /> Rev 4 <br /> December 2007 <br /> ' The values for the LCS and LCSD are used to calculate the Percent Recovery (PR), an estimate of the <br /> accuracy of the analytical process. The Average PR can be calculated using the following general equation: <br /> ' Average PR= 100((LCS + LCSD)/2(SA) <br /> where: PR= Percent Recovery <br /> ' LCS= Laboratory Control Sample Result <br /> LCSD=Laboratory Control Sample Duplicate Result <br /> SA= Spiked Amount <br /> ' H&P calculates the PR for each set of spikes (LCS and LCSD) and the resultant value is included in the <br /> QA/QC section of the report. <br /> 1 <br /> 16.7 Relative Percent Difference <br /> ' The Relative Percent Difference (RPD) is calculated from LCS and LCSD data and is used to estimate <br /> overall method precision. The RPD can be calculated using the following general equation: <br /> ' RPD= 100(LCS—LCSD)/(LCS+LCSD)/2 <br /> ' This RPD data is calculated for each set of spikes (LCS and LCSD)and is included in the QA/QC section of <br /> the report. <br /> ' 16.8 Laboratory Control Limits <br /> Each certified laboratory establishes their own set of Laboratory Control Limits (LCL's). These limits <br /> ' include criteria such as recovery ranges and maximum allowable RPD's. H&P has established the following <br /> list of control limits for EPA Method TO-14A/15 : <br /> ' Average percent recovery Relative Percent difference Marginal Exceedance Limit <br /> Soil Vapor LCS <br /> ' All Targets 65 - 135 <30 <40 <br /> 16.8.1 LCS Marginal Exceedance <br /> The current typical list of target compounds contains 65 target analytes. in yamn <br /> 1 u Relatiye <br /> n,...,ent n7PC re„,.e innrn and no ...............a.. may ,..,,,,.,.a nnoc nnr, If any analyte exceeds <br /> ' the QAQC limit of 65-135% recovery,the analyte is to be qualified in the data report. <br /> QAQC limits may be changed due to control chart evaluations. <br /> ' 16.8.2 Marginal Exceedance Randomness. <br /> The LCS marginal exceedance allowance assumes randomness of the exceedance for all <br /> compounds. The analyst can monitor the occurrence of LCS compounds using the Laboratory <br /> ' Page 23 of 24 <br />