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AUTOMATED PRESSURIZED FLUID EXTRACTION WITH IN-LINE CLEAN-UP FOR DETERMINATION OF PESTICIDES IN COMPOSITE DIETS.
Citation:
Morgan, J N. AUTOMATED PRESSURIZED FLUID EXTRACTION WITH IN-LINE CLEAN-UP FOR DETERMINATION OF PESTICIDES IN COMPOSITE DIETS. Presented at AOAC International Annual Meeting, Kansas City, MO, September 9-13, 2001.
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:
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 organophosphate 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 determiantion of thirty-seven organophosphate pesticides in composite diet samples. The current study evaluated an automated system for performing the extraction and cleanup in one step. C18 (5g), diatomaceous earth (5g) and composite diet sample (5g) mixed with diatomaceous earth (3g) were layered in a 33 mL pressurized fluid extractoin was performed at 80 degree C and 1000 psi. This technique was applied to composite diet samples varying in fat content and fortified with organophosphate pesticides. Organophosphate pesticides were quantititated by capillary GC using a DB-17 column with flame photometric detection (phosphorous mode). Results of this study demonstrated that the procedure separated the pesticides from greater than 95% of the lipid material. Pesticide recoveries fell within the target range of 60 to 140%. Results obtained with this automated technique compare favorably with the more laborious procedure utilizing PFE and column clean-up.