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ELEGANT ENVIRONMENTAL IMMUNOASSAYS
Citation:
Van Emon, J M., W C. Brumley, AND A W. Reed. ELEGANT ENVIRONMENTAL IMMUNOASSAYS. Presented at American Chemical Society 221st National Meeting, Immunochemistry Summit IX Symposium, San Diego, CA, April 1-5, 2001.
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:
Immunochemical methods are based on selective antibodies directed to a particular target analyte. The specific binding between antibody and analyte can be used for detection and quantitation. Methods such as the enzyme-linked immunosorbent assay (ELISA) can provide a sensitive, specific, simple to perform, and cost-effective analysis for many compounds of environmental and human health concern. ELISAs can be designed as rapid field screening, semi-quantitative analysis or as quantitative laboratory procedures. Thus, immunochemical methods are responding to the analytical challenges of environmental monitoring and regulatory programs. Advancements in environmental immunoassays have expanded their role from field screening methods to highly quantitative procedures that can compete with chromatographic methods in the laboratory. This progression of environmental immunoassays was initiated by field trials such as those performed under the U.S. EPA Superfund Innovative Technology Evaluation (SITE) Program. Several of these SITE studies have been conducted by the NERL-Las Vegas laboratory. The first of these trials determined the performance of two pentachlorophenol immunoassays in comparison to a gas chromatography (GC) procedure. Much was learned from this first field trial including appropriate quality control measures, data comparability concerns, and how to perform a sensitive analytical method at a contaminated site.
Immunoassays have now evolved as rapid and reliable methods to support human exposure assessment studies for pesticide residues, environmental degradation products, and metabolites. Immunoassays to detect chlorpyrifos (O,O-diethyl-O-{3,5,6-trichloro-2-pyridyl]-phosphorothioate and its metabolite TCP (3,5,6-trichloro-2-pyridinol) in food, track-in dirt, house dust and urine have been applied to samples from occupational and nonoccupational exposure surveys. The immunoassays performed comparably with gas chromatography/mass spectrometry (GC/MS) methods at low ppb levels; however, sample preparation was minimal with a high sample throughput and at a lower cost.
This work has been funded wholly or in part by the U.S. Environmental Protection Agency and has been approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.