Standardization and optimization of assays

Optimization with the goal to maximize precision of results, to determine optimum assay conditions, and to assess the effect of changes on the assay requires a rigid statistical evaluation of the error structure of the assay. The approach of Ekins (1979) for RIA is valid for EIA as well and is based on rather simple concepts. Rodbard (1978) used a much more complex approach to analyze the error structure of EIA. 

In the method of Ekins, a response-error relationship (RER) is established by plotting the error of the response variable against the response (e.g., 10 replicates for each dose plotting the SD against the response Fig. 15.13). 

A large list of criteria can be made for ideal material standards (stability, homogeneity, absence of contaminants, accurate division into smaller aliquots, uniform and low moisture content, identity of properties with the test substance). Activity of standard material is quantitated in internationally accepted units (lU in immunology, U in enzymology in enzymology lU denotes inhibitory international units). 

Standardization defines the concentrations or activities of substances which cannot be characterized adequately by chemical or physical means (Rowe et al., 1970a, b, c World Health Organization, 1972 Batty and Torrigani, 1980). Attempts have been made to standardize conjugates for EIA (Batty and Torrigani, 1980). 

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