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IMMUNOASSAY ANALYSIS FOR CHLORPYRIFOS IN FOODS
Citation:
Van Emon, J M. AND A W. Reed. IMMUNOASSAY ANALYSIS FOR CHLORPYRIFOS IN FOODS. Presented at 37th Annual Pesticide Residue Workshop and Florida Foodborne Pathogen Analysis Conference, St. Petersburg, FL, July 16-21, 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:
Chlorpyrifos is widely used in agriculture on fruits and vegetables. The tolerances for chlorpyrifos on produce range from 0.1-8.0 ppm. Residue detection is commonly performed by gas chromatography following various cleanup procedures. However, the required cleanup can make the entire analytical process laborious and time-consuming. We have developed streamlined approaches for the detection of chlorpyrifos in various food matrices. One method utilizes a sonic extraction followed by dilution and detection with an enzyme linked immunosorbent assay (ELISA). Another approach is to perform the ELISA on dilutions of simple food homogenates. Recoveries for either procedure range from 74-95% for various baby foods (e.g., meat, vegetables and fruit). Cleanup with solid phase extraction was not necessary but can be used for more difficult matrices especially composite food samples. The ELISA could tolerate 2% acetonitrile and up to 5% methanol and had a detection range of 0.2-100 ng/mL. Chlorpyrifos levels of 5- 400 ppb could be determined using a 10 g sample. These methods are being extended to samples from a human exposure duplicate diet study.
This work has been funded wholly or in part by the United States Environmental Protection Agency and has been approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.