Citation:

Chuang, J. C., J M. Van Emon, A W. Reed, AND N. Junod. EVALUATION OF IMMUNOASSAY METHODS FOR DETERMINATION OF 3,5,6-TRICHLORO-2-PYRIDINOL IN MULTIPLE SAMPLE MEDIA. Presented at EPA, Las Vegas EnviroExpo: Moving Towards Balance, Las Vegas, NV, December 9, 2004.

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:

Two enzyme-linked immunosorbent assay (ELISA) methods were evaluated for the determination of 3,5,6-trichloro-2-pyridinol (3,5,6-TCP) in multiple sample media (dust, soil, food, and urine). The dust and soil samples were analyzed by the RaPID (TM) commercial immunoassay testing kit based on antibody-coated magnetic particles. The food and urine samples were analyzed by a solid-phase 96-microwell plate immunoassay format. Methanol was used as the extraction solvent for the preparation of the dust and soil samples for analysis by both the ELISA and gas chromatography/mass spectrometry (GC/MS) procedures. Chlorobutane was used for the extraction of the urine samples for each method. The food samples were extracted with methanol for GC/MS and with acidic methanol for ELISA. The percent difference of the duplicate RaPID assays ranged from 0 to 43.4% for dust and from 0 to 47.9% for soil. The percent relative standard deviation of the 96-microwell plate triplicate assays was 15% or less for food and urine samples. Quantitative recoveries of 3,5,6-TCP were obtained for the spiked dust, soil, food and urine samples by the ELISAs ranging from 71 to 102%. Quantitative recoveries (>90%) of 3,5,6-TCP were also obtained for these samples by GC/MS. The overall method precision of these samples was within +/- 10% using the GC/MS procedure. The immunoassay and GC/MS data were highly correlated, with correlation coefficients of 0.98 for dust, 0.98 for soil, 0.93 for food and 0.98 for urine. Both ELISA methods can be used as quantitative monitoring tools for 3,5,6-TCP concentrations in dust, soil, food, and urine samples to reduce analytical costs and increase sample throughput.

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Record Details: