Laserfiche WebLink
• Holding Time: The holding time for analysis of trip blanks begins at the tie the oldest <br /> sample in the set is collected. <br /> Matrix Spike Samples <br /> Matrix spikes are performed by the analytical laboratory to evaluate the efficiency of the sample <br /> extraction and analysis procedures and are necessary because sample matrix interference may <br /> have a widely varying effect on the accuracy and precision of the extraction analysis. The matrix <br /> spike is prepared by the addition of known quantities of target compounds to a sample. The <br /> sample is extracted and analyzed, the results of the analysis are compared with the known <br /> additions, and a matrix spike recovery is calculated giving an evaluation of the accuracy of the <br /> extraction and analysis procedures. <br /> Matrix spike recoveries are reviewed to check that they are within acceptable range. However, <br /> acceptable ranges vary widely with both sample matrix and analytical method. Matrix spikes and <br /> matrix spike duplicates will be analyzed by the laboratory at a frequency of at least 1 per 20, or 5 <br /> percent of the primary field samples. Typically, matrix spikes are performed in duplicate to <br /> evaluate the precision of the procedures as well as the accuracy. Precision objectives (represented <br /> by agreement between matrix spike and matrix spike duplicate recoveries) and accuracy <br /> objectives (represented by matrix spike recovery results) are based on statistically generated <br /> limits established annually by the analytical laboratory. It is important to note that these <br /> objectives are to be viewed as goals, not criteria. If matrix bias is suspected, the <br /> associated data will be qualified and the direction of the bias indicated in the data validation <br /> report. The laboratory will provide matrix spike and matrix spike duplicate acceptance criteria. <br /> Surrogate Standard <br /> Surrogates are added to each soil and aqueous sample for organic analysis. The results of <br /> surrogate standard determinations are compared with true values spiked into the sample matrix <br /> before extraction and analysis, and the percent recoveries of the surrogates are calculated. If these <br /> recoveries fall outside control limits, the associated data may be affected. If a surrogate recovery <br /> Environmental/LNC/Workplan/Appendix3.wpd 14 <br />