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IMMUNOASSAYS FOR FOOD ANALYSIS
Citation:
Cullen, S J., J M. Van Emon, K Robbins, AND A W. Reed. IMMUNOASSAYS FOR FOOD ANALYSIS. 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:
Chlorpyzifos is widely used in agriculture on fruits and vegetables. According to federal guidelines, tolerances for chlorpyrifos an produce range from 0.1 ppm to 8 ppm. Detection of these residues is commonly performed by gas chromatography; however, the cleanup required makes the procedure laborious and time-consuming. We have developed a streamlined approach for the detection of chlorpyrifos in various food matrices. The method utilizes a sonic extraction, followed by dilution and detection with either a magnetic particle enzyme linked irnmunosorbent assay (ELISA) or a plate ELISA. Recoveries ranged from 74-.95% for various baby foods (e.g., chicken noodle dinner, spinach, apple-banana, arid broccoli carrots arid cheese), Cleanup with solid phase extraction was not necessary but could be used for more difficult matrices. The ELISAs could tolerate 2% acetonitrile and up to 5% methanol. The plate ELISA has a detection range of 0.2 - 100 ppb while the magnetic particle assay has a limited range of 1-3 ppb. Chlorpyrifos levels of 5 - 400 ppb could be determined using a 10 g sample. The method is being extended to duplicate diet exposure samples.
The U.S.EPA through its Office of Research and Development (ORD) funded this research and approved this abstract as a basis for a poster presentation. The actual presentation has not been peer reviewed by EPA. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.