Abstract
Sensitive immunoassays, such as the enzyme‐linked immunosorbent assays (ELISA) and the latex agglutination assay are sensitive to non‐specific reactions. Analysis of the reaction kinetics of the ELISA is highly useful in recognizing false positive results, as was demonstrated for assaying of staphylococcal enterotoxin A (SEA). The regression coefficient obtained after plotting the ELISA extinction values against the log10 of the reciprocal serial dilutions of the test sample was identical for SEA produced by several strains of Staphylococcus aureus. Regression coefficients obtained by the cross‐reacting substances protein A and lysozyme differed significantly from that obtained for SEA. Also, the maximal extinction values obtained for, among others, the cross‐reacting substances present in walnut extracts, differed significantly of that obtained for SEA. Food matrices were found to influence the regression coefficient only if the sample dilution factor was below 10.