DEVELOPMENT OF A HIGHLY SENSITIVE ENZYME-LINKED-IMMUNOSORBENT-ASSAY FOR ATRAZINE - PERFORMANCE EVALUATION BY FLOW-INJECTION IMMUNOASSAY

Specific polyclonal antibodies to the herbicide atrazine o-N-ethyl-N'- isopropyl-1,3,5-triazine-2,4-diamine) have been raised by immunizing t hree New Zealand rabbits. With the antisera (As) a highly sensitive en zyme-linked immunosorbent assays (ELISA) has been developed to determi ne atrazine in water samples. Several usable competitive immunoassays have been obtained by screening a battery of nine enzyme tracers (ETs) and three antisera, The optimized ELISA presents an IC50 of 0.28 nM ( 60 ng l(-1)) and a detection limit of 0.043 nM (9 ng l(-1)). Cross-rea ctivity studies have proved that the immunoassay is specific for atraz ine while other triazine compounds are only detected on a minor extent , The flow injection immunoanalysis (FIIA) method has an IC50 of 2 nM (0.47 mu g l(-1)) reaching a detection limit of 0.35 nM (75 ng l(-1)). The performance of both methods has been evaluated by analyzing water samples containing mixtures of atrazine and other pesticides at the p pb level, For this purpose two candidate reference materials have been used (A and B) and a spiked sample stored on Empore disks (sample C). A close correspondence was found between the results obtained with bo th immunochemical techniques.