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' SOP TO-14A/15 Rev 4 December 2007 ' It should be noted that this detection limit might vary due to low sample amounts or dilutions. In most cases, H&P reports EQL values roughly 5-10 times the MDL. These values are in accordance with the recommended values ' 16.3.3 Reporting Limit ' The reporting limit is a limit below which regulators or clients are uninterested or will not regulate. Thus TO-14/TO-15 compounds that are detected but are below the established reporting limit are reported as non-detect. ' 16.4 Blanks ' A Method Blank is an analyte free matrix sample, run through the sample preparation and analysis procedures of those used for samples. These blanks check the levels of contamination for the method. Blanks must be run at a frequency of one per batch of samples or preparation method. If a contaminate is ' found the source of contamination must be investigated and measures taken to correct, minimize or eliminate the problems if: ' a) the target analytes in a reagent blank are higher than the reporting limit (dilution factors taken into account) in effect at the time ' b) the blank contamination exceeds a concentration greater than 1/10 of the measured concentration of any sample in the associated blank sample batch or the blank contamination exceeds the concentration present in the samples and is greater than 1/10 of the specified regulatory limit. ' 16.5 Matrix Spike/Matrix Spike Duplicate and Lab Control Sample The Matrix Spike (MS) and Matrix Spike Duplicate (MSD)are two aliquots of the same sample, which have ' been which have been spiked with a known concentration of a target analyte. Together, the results of these two sample spikes are used to indicate method precision and accuracy, and to characterize the effects, if any, of matrix interference. H&P usually analyzes only laboratory control samples and their duplicates since vapor samples typically have little matrix effects. The LCS is spiked directly into a clean minican or Summa Canister with the same analytes at the same concentrations as the ccv and is analyzed with the sample batch. If the results of the Laboratory Control Sample (LCS) fails, the failing analyte is to be qualified. sefreet+ve ....4:.11 .....A*1.A*Aker. A...I thR. h-at6. _ealialyzea A LCS is an aliquot of zero air or helium spiked with all the ' analytes of interest. (Certain locales have a different definition of an LCS, e.g., for the LARQCB an LCS is a low level spike that is performed after a batch of samples that have all tested non-detect. This is supposed ' to prove that the method was functioning during the analysis of the batch.) ' 16.6 Percent Recovery Calculation ' Page 22 of 24