Matrix effects immunoassay development, analyte

Using a simple solvent extraction procedure to minimize matrix effects, a diclofop-methyl immunoassay was developed for milk, a number of edible plant products, and other matrices. Gas chromatography (GC) and liquid scintillation counting (LSC) of a C-labeled analyte were used as reference methods to compare with enzyme immunoassay (EIA) results. The methods were well correlated, with comparison of EIA... 

Evaluation, characterization, and testing of a particular analytical method is necessary to ensure the intended use of the method is met. In general, this process requires the determination of intra-and interlaboratory studies for precision and bias, method detection limits, matrix effects, interferences, limits of reliable measurements and ruggedness of the method. Before the EPA commits time and resources for an in-depth evaluation study, the developer must meet certain developmental criteria or justify why they were not met. The developer must also clearly define all necessary reagents as well as the underlying basis of the immunoassay. 

When appropriate, a dynamic (in-use) method evaluation of the assay will be performed following completion of the EMSL-LV single laboratory evaluation or confirmation. This type of evaluation is intended for immunoassays that are well-characterized and mature (i.e., a method where the developer has extensive performance data regarding matrix effects, cleanup, cross-reactivity, confirmatory analyses, and any other pertinent information). The data obtained during the dynamic evaluation will actually be used in a monitoring program. A dynamic evaluation can occur only where there is an immediate and urgent need for an analytical method. 

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