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March 7, 2019 | Page B-3 File No. 0504-119-01 <br />Trip Blanks <br />Trip blanks are analyzed to provide an indication as to whether volatile compounds have <br />cross-contaminated other like samples within the transportation process to the laboratory. None of the <br />analytes of interest were detected in the trip blank. <br />Matrix Spikes/Matrix Spike Duplicates <br />Since the actual analyte concentration in an environmental sample is not known, the accuracy of a <br />particular analysis is usually inferred by performing a matrix spike (MS) analysis on one sample from the <br />associated batch, known as the parent sample. One aliquot of the sample is analyzed in the normal manner <br />and then a second aliquot of the sample is spiked with a known amount of analyte concentration and <br />analyzed. From these analyses, a percent recovery is calculated. Matrix spike duplicate (MSD) analyses are <br />generally performed for organic analyses as a precision check and analyzed in the same sequence as a <br />matrix spike. Using the result values from the MS and MSD, the relative percent difference (RPD) is <br />calculated. <br />A laboratory control sample/laboratory control sample duplicate (LCS/LCSD) sample set was performed in <br />lieu of a MS/MSD analysis. <br />Laboratory Control Samples/Laboratory Control Sample Duplicates <br />A laboratory control sample (LCS) is a blank sample that is spiked with a known amount of analyte and then <br />analyzed. An LCS is similar to an MS, but without the possibility of matrix interference. Given that matrix <br />interference is not an issue, the LCS/LCSD control limits for accuracy and precision are usually more <br />rigorous than for MS/MSD analyses. Additionally, data qualification based on LCS/LCSD analyses would <br />apply to all samples in the associated batch, instead of just the parent sample. The percent recovery control <br />limits for LCS and LCSD analyses are specified in the laboratory documents, as are the RPD control limits <br />for LCS/LCSD sample sets. <br />One LCS/LCSD analysis should be performed for every analytical batch or every 20 field samples, whichever <br />is more frequent. The frequency requirements were met for all analyses and the percent recovery and RPD <br />values were within the proper control limits. <br />FIELD DUPLICATES <br />In order to assess precision, field duplicate samples were collected and analyzed along with the reviewed <br />sample batches. The duplicate samples were analyzed for the same parameters as the associated parent <br />samples. Precision is determined by calculating the RPD between each pair of samples. If one or more of <br />the sample analytes has a concentration less than five times the reporting limit for that sample, then the <br />absolute difference is used instead of the RPD. The RPD control limit for groundwater samples is <br />35 percent. <br />SDG 590-10350-1: One field duplicate sample pair, MW-3:013019 and DUP:013019, was submitted with <br />this SDG. The precision criteria for all target analytes were met for this sample pair.