COMPARISON OF A TIME-RESOLVED FLUORESCENCE IMMUNOASSAY AND AN ENZYME-LINKED-IMMUNOSORBENT-ASSAY FOR THE ANALYSIS OF ATRAZINE IN WATER

Immunoassays for atrazine based on a time-resolved fluorescent label a nd an enzyme label were optimized and utilized to measure atrazine in water. The time-resolved fluorescent immunoassay (TRFIA) was based on a polyclonal antibody and a europium label, whereas the enzyme-linked immunosorbent assay (ELISA) utilized a monoclonal antibody and horsera dish peroxidase as the label. Detection limits and IC50 values calcula ted from standard curves were 0.05 +/- 0.03 and 0.17 +/- 0.08 ng/mL (n = 8) for the TRFIA, respectively, and 0.05 +/- 0.04 and 0.3 +/- 0.2 n g/mL (n = 17) for the ELISA, respectively. Four different environmenta l water samples were fortified at various levels of atrazine. When the se samples were analyzed, the % RSD for replicate fluorescence or abso rbance readings was small (5 and 6%, respectively). The average accura cies for the TRFIA and ELISA were 1.4 +/- 0.42 (n = 13) and 1.0 +/- 0. 38 (n = 13), respectively, reflecting the slight bias of the TRFIA. TR FIA offers an advantage over ELISA in that the fluorescent label is le ss susceptible to interferences that inhibit enzyme activity and reage nts may be more stable than enzyme reagents.