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This powerpoint presentation begins by presenting research objectives that include the following: evaluate the impact of not strictly following U.S. Environmental Protection Agency (USEPA)guidelines for preservation and storage of synthetic organics;evaluate the impact of extended storage atroom temperature on analyte stability,e.g. simulate long transit times;evaluate impact of eliminating "dangerousgoods" from preservation, e.g. facilitate international transport; and,eliminate dual stage preservation,e.g. de-chlorination followed by acidification. Reasons for evaluating alternatives include the following: there are inconsistencies between various500 series methods for the same analyte;two-stage preservation for disinfectedsamples is a source of field errors; for international projects, sending acids issometimes prohibited, Keep It Simple; and,the World Health Organization (WHO) regulates some analytes that are notcovered in USEPA regulations and there isno literature data on preservation. Observations on pesticide/SOC analysisand degradation with 525 scheme include the following:under refrigeration, almost all target analytes arestable for 28 days when acidified;however, without acidification but with refrigeration,almost all target analytes are stable for at least 7 days;without refrigeration there are significant differencesby compound class with acidification vs neutral pH, andis also somewhat matrix dependent; and,for some compounds acidification enhancesdegradation whereas de-chlorination does not. Significant observations from PartOne studies indicate:cyanazine unstable if acidified, butdechlorination is acceptable (contrary to 525);heptachlor is relatively stable withoutacidification (more stable than with acid);diazinon is relatively stable without acidification; and, a few USEPA regulated analytes show significantdegradation when preserved per methodrequirements. Studies in process and recommendations include the following:527 Preservation in Matrices (as was donewith 525 options in part 1);evaluation of Room Temperature Storagewith 527;develop Triage Scheme for DataInterpretation Based on Findings; it appears clear that USEPA can move awayfrom two-stage preservation; and, USEPA can alsoclarify existing options. Includes table, figures.

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Edition: Vol. - No. Published: 11/01/2008 Number of Pages: 39File Size: 1 file , 1.4 MB