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COMPARISON OF FIVE EXTRACTION METHODS FOR DETERMINING INCURRED AND FORTIFIED PESTICIDES IN DIETARY COMPOSITES
Citation:
Morgan, J N., L Rosenblum, AND S. Garris. COMPARISON OF FIVE EXTRACTION METHODS FOR DETERMINING INCURRED AND FORTIFIED PESTICIDES IN DIETARY COMPOSITES. JOURNAL OF AOAC INTERNATIONAL 85(5):1167-1176, (2002).
Impact/Purpose:
The overall objective of this research 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 provides the tools needed to collect and analyze food samples and to design and understand dietary measurements. The current specific objectives are:
1. to investigate more efficient methods for characterizing population exposures in dietary measurements studies (short-term subtask initiated in FY00; extramural);
2. to develop and improve analytical methods for contaminants in composite food samples collected in dietary measurements studies (long-term subtask; in-house);
3. to improve the model and food database system used in measurements studies for estimating dietary exposure and identifying sources (long-term subtask; extramural).
Description:
U.S. EPA's National Exposure Research Laboratory conducts research to measure exposure of individuals to chemical pollutants through the diet. In support of this research, methods are being evaluated for determination of pesticides in dietary composite samples. In the present study, Soxhlet, blender, microwave-assisted, pressurized fluid, and supercritical fluid extraction methods were compared for the determination of incurred and fortified pesticides in four dietary composites, which varied in fat and water content. Incurred pesticides were chlorothalonil, chlorpyrifos, DDE, dicloran, dieldrrin, endosulfan, endosulfan I, malathion, cis and trans permethrin, and trifluralin. Fortified pesticides were x- and y-chlordane, hexachlorobenzene, and fonofos. Concentrations of the individual pesticides were between 0.2 and 20 ng/g composite. All five methods tested were able to extract pesticides from dietarycomposites. Most incurred pesticides were recovered from the dietary composites within the range of 59-140% of expected values. Recovery of fortified pesticides was between 60 and 130%. Microwave extraction led to significantly higher concentrations of seven pesticides. Blender extraction yielded significantly higher concentrations of chlorothalonil and fonofos. Water content was a signficant factor in recovery of chlorothalonil, and fat content was a significant factor in recovery of fonofos. In designing an exposure study, the method selected would be determined by number of samples to be extracted, analyte stability, and cost.