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Page 7 of 24 <br />SOP NUMBER 28.0 AnalvOcal Data Validation <br />Generally, the diluted result can be considered to be the more accurate result, as long as the <br />diluted concentration is well above the detection limit. Therefore, the data reviewer can <br />generally discern a potential bias direction from a comparison of the diluted and undiluted <br />results. For example, if the diluted result is higher than the original result, the bias direction <br />(associated with the original result) is considered to be potentially low. <br />A qualifier code of "DL" will be assigned to all results qualified on the basis of serial dilution <br />results along with an appropriate bias code. <br />4.1.6.1.3 Internal Standards <br />Internal standards are used routinely in the analysis for metals by ICP-MS; however, internal <br />standards may be used in the analysis of metals by ICP-ES. Internal standard recoveries for <br />every sample and standard (as the requested level of reporting permits evaluation) will be <br />compared to an acceptance range of 30-00%. Results associated with internal standard <br />recoveries outside the acceptance range where the sample was not diluted and reanalyzed will be <br />qualified as estimated (J/UJ). If upon reanalysis the internal standard recoveries are still outside <br />the acceptance range, the results will be qualified as estimated (J/UJ). <br />4.1.6.1.4 Anion/Cation Balance <br />Because water is generally electrically neutral, the sum of the dissolved cation concentrations <br />(expressed in milli-equivalents per liter) should equal the sum of the dissolved anion <br />concentrations. For projects in which the major cations and anions are being analyzed, the data <br />reviewer may evaluate whether there is an acceptable balance between anion concentrations and <br />cation concentrations. It should be noted that both major cations and anions must be analyzed to <br />complete the anion/cation balance. In accordance with Standard Methods #1030F, the equation <br />used to calculate anion-cation balances is: <br />percent difference =100% x (Ecations - Eanions) / (Ecations + Eanions) <br />Laboratory accuracy control limits for these types of analytes are typically +30%. This level of <br />accuracy is considered to be fully acceptable in meeting the end use objectives of groundwater <br />monitoring. A 30% bias in the metals analysis corresponds to an anion-cation balance percent <br />difference of approximately 13%. Therefore, since a 30% bias is considered not to adversely <br />affect the usability of the data, an evaluation criterion of a percent difference less than f 13% <br />will be utilized for anion-cation balance evaluation. If the anion/cation balance is greater than <br />f13% the data reviewer should use professional judgement to discern likely causes of the <br />imbalance and need for qualification of data. <br />4.1.62 Organic Method Specific QC Measures <br />For organic methods, method specific QC measures may include surrogate compound recovery <br />and internal standard performance. Evaluation procedures for each of these QC measures are <br />described below. <br />Powertech <br />R Squared Inc <br />Rev 28-1 JAB Attachment A <br />4/23/2007