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.. - rj1111 <br /> A � r- d' <br /> a <br /> u <br /> r� <br /> i 13. MgrchA ivin� <br /> Organic sample concentrates are sorted by project, clearly <br /> l.,bcicd and rtorcd in a freezer for future reanalysis. <br /> Therefore, if methodological advances, changes in scope, or <br /> evidence .:f instrument malfun-tion are developed following <br /> analysis, :::amplete reprocessing of the sample is not <br /> necessary. Where applicable, it is more convenient to ship <br /> concentrates than to ship samples. Properly applied, this <br /> i measure .provi.des a means to detect systematic errors. <br /> Following analysis, all samples are kept for a minimum of <br /> 30 day,. in this way, questions raised during the review <br /> of data can be addressed by inspection of the sample or by <br /> complete reanalysis using a different method. Analysis for <br /> components subsequently added to the list of parameters to <br /> be measured and incompatible with previous sample workup <br /> may be analyzed without resampling. The chief quality <br /> } assurance feature provided by the archived samples is the <br /> I ability to use the archived samples to resolve problems <br /> which may be noted only as the data are compared and <br /> interpreted. <br /> ' flaw data for most procedures are kept in bound notebooks <br /> associated with the test or group of determinations. The <br /> Icompleted notebooks are filed in the laboratory for ready <br /> reference should future comparisons be desirable. Raw � <br /> chromatographic data, such as that collected in the <br /> quantitation of trace organics, are filed to permit <br /> critics: reexamination at any time. Such information is <br /> particularly useful in cases where the inspection of old <br /> data may yield clues regarding the presence of newly <br /> identified species. <br /> Raw GC/MS chromatograms are similarly archived together <br /> with the spectra of chromatographically isolated but <br /> unidentified components. In addition, raw GC/MS data are <br /> transferred to tape in an EPA-approved format in order to <br /> permit reprocessing to retroactively search for new classes <br /> of compounds or otherwise reexamine previously reported <br /> findings. <br /> .Ln addition to computer storage, a hard-copy printout of <br /> every sample report is filed under the client's name and <br /> saved for five years. <br /> C. Detection Limits <br /> The method detection limit is often defined as the minimum <br /> concentration of analyte which can be identified, measured, <br /> 1 VIII-2 <br />