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EVALUATION OF ANALYTICAL METHODS FOR DETERMINING PESTICIDES IN BABY FOOD AND ADULT DUPLICATE-DIET SAMPLES
Citation:
Chuang, J. C., K. Hart, J. S. Chang, A W. Reed, AND J M. Van Emon. EVALUATION OF ANALYTICAL METHODS FOR DETERMINING PESTICIDES IN BABY FOOD AND ADULT DUPLICATE-DIET SAMPLES. Presented at Immunochemistry Summit VIII Meeting, San Francisco, CA, March 26-31, 2000.
Impact/Purpose:
The overall objectives of the task include several components: (1) develop immunochemical methods for compounds difficult to analyze by conventional methodologies; (2) tailor immunochemical methods to support specific human exposure assessment studies; (3) team immunochemical sample preparations with instrumental analysis such as mass spectrometry for in-depth sample characterization; (4) provide methods to support NERL's human exposure and environmental monitoring efforts; (5) provide analytical methods that improve risk assessments by reducing the amount of uncertainity in environmental measurements; (6) provide multimedia analytical methods to support an integrated multimedia approach to assess and characterize risk to human health and the environment; (7) provide sponsorship of annual immunochemistry research meetings as a forum for stimulating interest and discussion on current or emerging bioanalytical methods; (8) develop and incorporate rapid, cost-effective laboratory and field portable immunochemical techniques such as enzyme-linked immunosorbent assay (ELISA) methods into monitoring studies and human exposure field surveys to delineate sub-populations of "highly exposed" individuals for detailed follow-up studies.
Specific method needs have been identified through consultations with client office personnel. This Task strives to fulfill those needs as appropriate. In particular, methods for pyrethroids, e.g., permethrin, cypermethrin, and deltamethrin are being developed and evaluated. Efficient sample preparations are under development for exposure samples using pressurized liquid extraction. Confirmation will be achieved using high performance liquid chromatography (HPLC). A rapid immunoassay approach for the analysis of 2,4-D in urine will be completed and a SOP and report written. Immunoaffinity chromatography sample preparations for the pyrethroids will be developed. Work will continue on the application of antibody replacements such as molecularly imprinted polymers. Additional candidate analytes will be identified for a tiered approach and to guide development of the next Task. Flexibility will be maintained to address methods and measurement issues as they arise during the task period which ends in FY06. The objective of the Task is to develop bioanalytical methods to support exposure monitoring studies during the task period.
Description:
Determinations of pesticides in food are often complicated by the presence of fats and require multiple cleanup steps before analysis. Cost-effective analytical methods are needed for conducting large-scale exposure studies. We examined two extraction methods, supercritical fluid extraction (SFE) and accelerated solvent extraction (ASE), coupled with various cleanup techniques for the analysis of pesticides in baby foods. The SFE-GC/MS method did not provide quantitative recoveries (<50%) of the pesticides spiked into fatty baby foods. This led to the evaluation of ASE-ELISA and ASE-GC/MS using a Dionex Model ACE 2000 system. Two solvents (acetonotrile [ACN] and ethyl acetate), three extraction temperatures (80?C, 100?C, and 120?C), and several different sample clean-up procedures were evaluated. A set of ASE conditions was developed that consists of extracting baby food with ACN at 80?C under 2,000 psi pressure. An ENVICarb SPE condition was also developed to clean the ACN extract. The cleanup fraction was analyzed by ELISA for chlorpyrifos and by GC/MS for malathion, chlorpyrifos, p,p'DDE, and p,p'-DDT. Duplicate diet samples were analyzed for target pesticides by ASELISA axed by ASE-GC/MS. Concentrations of these compounds ranged from <0.3 to 110 ppb.
This work has been funded wholly or in part by the U.S.EPA under contract 68D4-0023 to Battelle. It has been subjected to Agency review anal approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.