Performance characteristics of a novel magnetic‐particlebased enzyme‐linked immunosorbent assay for the quantitative analysis of atrazine and related triazines in water samples

The performance characteristics of a magnetic‐particle‐based solid‐phase enzyme‐linked immunosorbent assay (ELISA) requiring no sample preparation for the quantification of atrazine and related triazines in groundwater samples is described. Water samples and HRP‐labeled atrazine are incubated with the antibody‐coupled solid phase for 15 min. A magnetic field is then applied to the solid phase to wash and remove free HRP‐labeled atrazine and to ensure the removal of potential interfering substances. After 20 min of color development using hydrogen peroxide/TMB, the reaction is stopped by the addition of acid. Photometric analysis of the final colored reaction was made using a specially designed microprocessor‐controlled photometer with extensive data reduction capability. The assay was found to be free of interferences when challenged with high concentrations of inorganic ions and a wide variation in sample pH. Sensitivity of the assay was 50 ppt based on 95% B/B₀. Assay precision demonstrated coefficients of variation of less than 10%. The ELISA compared favorably with GC/MS measurements. The broad antibody specificity allows for the detection of a majority of triazines.