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COMPARISON OF FIVE EXTRACTION METHODS ON INCURRED AND FORTIFIED PESTICIDES IN COMPOSITE DIETS: BLENDER, SOXHLET, ASE, MICROWAVE AND SFE
Citation:
Rosenblum, L. COMPARISON OF FIVE EXTRACTION METHODS ON INCURRED AND FORTIFIED PESTICIDES IN COMPOSITE DIETS: BLENDER, SOXHLET, ASE, MICROWAVE AND SFE. Presented at AOAC Central Regional Meeting, Columbus, OH, November 1-3, 2000.
Impact/Purpose:
The objective of this task is to develop state-of-the-art methods for measuring xenobiotic compounds, to include the isolation of the analyte from the appropriate matrix (extraction), preconcentration (typically sorbent-based), and analysis via GC/MS and/or LC/MS. Once established, these methods will be applied in small scale pilot studies or demonstration projects. Particular emphasis will be placed on methods which are readily transferable to other laboratories, including those within the Human Exposure and Atmospheric Sciences Division (HEASD), the National Exposure Research Laboratory (NERL), other EPA Laboratories, Program Offices, Regions, and academic institutions.
Specific objectives of this task include the following:
1) Development of GC/MS and LC/MS methods for the measurement of key xenobiotic compounds and their metabolites (to include the pyrethroid pesticides, perfluorinated organic compounds, and the BFRs) in relevant environmental and biological matrices.
2) Development of efficient low cost methods for the extraction and clean up of these compounds collected from relevant matrices.
3) Determination of xenobiotic compound and metabolite concentrations in samples derived from laboratory and field monitoring studies to help assess exposures and evaluate associated risks.
Description:
The USEPA National Exposure Research Laboratory studies dietary exposure to a diverse group of semi-volatile pesticides by analyzing 24 hour duplicate composite diets. The pesticides of interest include organochlorines, organophosphates, anilines, and triazines. Currently, there are no official methods for pesticide analysis of composite samples that include fatty and non-fatty foods. Composite diets consisting of multiple food items with field-incurred or laboratory-fortified pesticides were created to compare extraction efficiency by Soxhlet, blender, microwave, ASE, and SFE. Similar pesticide recoveries were obtained by all extraction methods, though the methods varied widely in instrument cost, extraction time, and solvent use. Co-extractants were removed using a novel clean-up method that included pre-separation in the large volume injector of a GC/MS. The extraction, clean-up, and determinative steps permit the analysis of non-polar and moderately polar pesticides in fatty samples with a method detection limit of about 1 ng/g for thermally stable semi-volatile pesticides and reduce solvent consumption.