ARCHIVED REPORTS_DR OM AGREEMENT 2017 JANUARY

Home Browse Search

Quality Assurance Project Plan for Removal Action APN 209-450-03,Mountain House,CA Page 8 5.2.1 Laboratory Reagent Blanks A laboratory reagent blank is deionized water and it is extracted by the laboratory and analyzed as a sample. Analysis of the reagent blank indicates potential sources of contamination from laboratory procedures (e.g., contaminated reagents, improperly cleaned laboratory equipment, or persistent contamination due to presence of certain compounds in the ambient laboratory air). A reagent blank will be analyzed at least once each day for each method utilized by the laboratory for that day. 5.2.2 Field Equipment Blanks A field equipment blank is a sample that is prepared in the field by pouring distilled water into or through cleaned sampling equipment. The water is then collected and analyzed as a sample. Field equipment blanks are labeled such that they are not discernable as a blank to the laboratories. The field equipment blank gives an indication of degree of contamination from field procedures (e.g., improperly cleaned sampling equipment, cross-contamination). Field equipment blanks will be collected at a minimum frequency of at least one per ten, or 10 percent of primary field samples when non-dedicated equipment is utilized. The field equipment blanks will be analyzed using the same analyses requested for the associated primary samples. 5.2.3 Matrix Spike Samples Matrix spikes are performed by the analytical laboratory to evaluate the efficiency of the sample extraction and analysis procedures, and are necessary because matrix interference (that is, interference from the sample matrix,water or soil)may have a widely varying impact on the accuracy and precision of the extraction analysis. The matrix spike is prepared by the addition of known quantities of target compounds or acceptable surrogates to a sample. The sample is extracted and analyzed. The results of the analysis are compared with the known additions and a matrix spike recovery is calculated giving an evaluation of the accuracy of the extraction and analysis procedures. Matrix spike recoveries are reviewed to check that they are within acceptable range. However, the acceptable ranges vary widely with both sample matrix and analytical method. Matrix spikes and matrix spike duplicates will be analyzed by the laboratory at a frequency of at least one per twenty, or 5 percent of the primary field samples. Typically, matrix spikes are performed in duplicate, in order to evaluate the precision of the procedures as well as the accuracy. Precision objectives (represented by agreement between matrix spike and matrix spike duplicate recoveries) and accuracy objectives (represented by matrix spike recovery results) are based on statistically generated limits established annually by the analytical laboratory. It is important to note that these objectives are to be viewed as goals, not as criteria. If matrix bias is suspected, the associated data will be qualified and the direction of the bias indicated in the data validation report. 5.2.4 Field Duplicate Samples Field duplicate samples will be collected and analyzed to evaluate sampling and analytical precision. Field duplicates are collected and analyzed in the same manner as the primary samples. Agreement between duplicate sample results will indicate good sampling and analytical precision. Specific locations will be designated for collection of field duplicates prior to the start of field activities. Field duplicates will be collected at a frequency of 10 percent of the primary samples collected. The duplicate samples will be analyzed for all laboratory analyses requested for their primary sample counterparts. 5.2.5 Performance Evaluation Samples Double-blind performance evaluation (PE) samples may be submitted to the analytical laboratory during any Site investigation. These samples are used to assess the accuracy of analytical procedures employed CONDOR