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DETERMINATION OF PESTICIDES IN COMOSITE DIETS USING LARGE VOLUME PRESSURIZED FLUID EXTRACTION WITH IN-LINE SAMPLE PREPARATION
Citation:
Morgan, J N., T Hieber, P Kauffman, AND J. Brisbin. DETERMINATION OF PESTICIDES IN COMOSITE DIETS USING LARGE VOLUME PRESSURIZED FLUID EXTRACTION WITH IN-LINE SAMPLE PREPARATION. Presented at 40th Annual AFDOSS Florida Pesticide Residue Workshop, St. Petersburg, FL, July 20-23, 2003.
Impact/Purpose:
The overall objective of the MCEARD dietary exposure research program is to support NERL's human exposure measurement and exposure modeling efforts by reducing the amount of uncertainty in the dietary measurements critically needed for improved risk assessment. Specifically, the research conducted under this task provides the tools needed to analyze composite food and beverage samples for the presence of pesticides, starting with pyrethroids. The specific objectives of this task are to develop and improve analytical methods for contaminants in composite food and beverage samples collected in dietary measurements studies and to analyze small numbers of samples in support of these studies. A series of analytical methods and/or journal articles are anticipated through FY07.
Description:
USEPA's National Exposure Research Laboratory conducts research to measure the exposure of individuals to chemical pollutants through the diet, as well as other media. In support of this research, methods are being evaluated for determination of various classes of pesticides in composite diet samples. In previous work, pressurized fluid extraction (PFE) followed by diatomaceous earth and C18 reversed phase column chromatography was used in the determination of organophosphate pesticides in composite diet samples. PFE followed by diatomaceous earth and alumina column chromatography was used for a diverse mix of organochlorine and other pesticides. The current study evaluated an automated system for performing the extraction and cleanup in one step in a 100 mL PFE cell. Various combinations of sample amounts, extraction solvents and adsorbents were tested. Organophosphate pesticides were quantitated by gas chromatography with pulsed flame photometric detection. Organochlorine pesticides were quantified by gas chromatography/mass spectrometry in the selected ion monitoring mode. Results of this study demonstrated this automated procedure, using acetonitrile, a super absorbent polymer and C18, was comparable to the more laborious PFE/column chromatography methods used previously. Acetonitrile replaced a mixed solvent system of acetone/methylene chloride used in previous studies. Recoveries for most pesticides fell within the target range of 60 to 140%. Results obtained for organochlorine pesticides are preliminary and additional work is needed to optimize this system for those analytes.