Comparison of a Time-Resolved Fluorescence Immunoassay and an Enzyme-Linked Immunosorbent Assay for the Analysis of Atrazine in Water

Abstract

Immunoassays for atrazine based on a time-resolved fluorescent label and 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 horseradish peroxidase as the label. Detection limits and IC50 values calculated 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 ng/mL (n = 17) for the ELISA, respectively. Four different environmental water samples were fortified at various levels of atrazine. When these samples were analyzed, the % RSD for replicate fluorescence or absorbance readings was small (5 and 6%, respectively). The average accuracies 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. TRFIA offers an advantage over ELISA in that the fluorescent label is less susceptible to interferences that inhibit enzyme activity and reagents may be more stable than enzyme reagents. Keywords: Atrazine; triazine; herbicide; time-resolved fluorescence; immunoassay; enzyme-linked immunosorbent assay