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DETERMINATION OF PESTICIDES IN COMPOSITE BEVERAGE SAMPLES
Citation:
HIEBER, T. E., P. KAUFFMAN, J. BRISBIN, AND J. N. MORGAN. DETERMINATION OF PESTICIDES IN COMPOSITE BEVERAGE SAMPLES. Presented at 2005 Florida Pesticide Residue Workshop, St. Petersburgh, FL, July 17 - 20, 2005.
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 pesticides in composite dietary samples. Existing methods for pesticides generally have been developed for regulatory purposes and often do not have sufficiently low detection limits for exposure studies. Consequently, there is a need to improve the performance of these methods for analysis of pesticides in composite dietary samples.
In previous work, pressurized fluid extraction (PFE) followed by diatomaceous earth and C18 reversed phase chromatography was used in the measurement of organophosphate pesticides in composite solid food samples. PFE followed by diatomaceous earth and alumina column chromatography was used for a diverse mix of organochlorine and other pesticides. The current study was designed to evaluate the application of these and other techniques to determination of pesticides in low fat (1% of calories from fat) and high fat (13% of calories from fat) composite beverage samples.
Initial beverage method development efforts utilized milk fortified with organophosphate pesticides as a surrogate for composite beverages. Milk was applied directly to a diatomaceous earth column and extracted with various combinations of solvent. Recovery of organophosphate pesticides was generally unsatisfactory. Subsequently, PFE methods with diatomaceous earth and C18 (for organophosphate pesticides) and alumina (for organochlorine and other pesticides) column cleanup were optimized for composite beverage samples. Detection limits were generally within the sub-ppb to low ppb range. Recoveries were typically within the range of 60 - 140%. Finally, matrix solid phase dispersion (MSPD) techniques were evaluated. Traditional MSPD utilizing column chromatography was compared to MSPD performed in a pressurized fluid extractor. Recoveries were acceptable (60-140%) for most pesticides.