ARCHIVED REPORTS_FIELD NOTES AND PERMITS THROUGH 4_4_1997

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NRR-22-1995 18:56 GRADIENT P.031106 • • Surrogate spike recoveries to assess accuracy of the results relative to laboratory performance and specific sample matrix. Field duplicate BPDs to assess precision of the results relative to field sampling techniques and the specific sample matrix and representativeness of the sample aliquot to the area sampled. Instrument tunes and calibrations to assess accuracy and sensitivity of the results relative to the instrument performance. Internal standards to assess accuracy relative to instrument performance and specific sample matrix of the results. Quantitation limits to assess sensitivity of the results. Accuracy Holding limes The holding times were reviewed to ensure the accuracy of the reported results;exceeded holding times may cause biased low results due to sample degradation. The chain-of-custody (COC) for 5 of the samples indicated that the samples were preserved with hydrochloric acid (HCl); however, the other two COCl did not indicate presence or lack of sample preservative. During the data usability assessment, Gradient assumed that all the samples were preserved with HCl. The required analytical holding time for preserved volatile samples is 14 days from date of sample collection. The following sample analyses at the dilutions listed were not performed within 14 days of sample collection: MW462, MW4-62 1:10 (12/9/94), MW4-62 1:10 (12/12/94), MW4.62 1:100, MW4-62 1:200, MW5-51, MW5-51 1:10, MW5-DUP, MW5-DUP 1:10, MW5-EB, MW6-51 1:10, MW6-51 1:1000, MW7-60 1:100, MW9-60 1:10 (12/8/94), MW9-60 1:10 (12/12/94), MW10-54 1:10(12/8/94), MW1O-54 1:10(12/12/94), MWI1-60 1:40, MWII-DUP 1:40, MW 12-60 1:10, MW 12-60 1:100, MW 12-60 1:200, and MW21-110 1:100. The positive and nondetect results in these sample analyses have been qualified as estimated (J and UJ, respectively), and may be biased low. These results are usable as estimated values. Surrogate Spike Recoveries The surrogate spike recoveries were reviewed to assess the accuracy of the results relative to laboratory performance and specific sample matrix. All surrogates recovered within the QC limits of 80-120%, with the exception of surrogate bromofluorobenzene (BFB) that recovered below the QC limits in sample analyses MW1-55, MWI-DUP, MW4-62 1:10 (12/9/94), MW9- 60,MW9-60 1:10(12/8/94),MW10-54, MWIO-54 1:10(12/8/94),MW12-60 1:200, MW30-EB, TB5, and TB6. All positive and nondetect results in these sample analyses have been qualified as estimated (J and UJ, respectively) and may be biased low, as indicated by low surrogate recoveries. These results are usable as estimated values. g:\projeots\dq\9504I0U.mom 2 Gradient Corporation