Highly sensitive detection of bensulfuron-methyl by time-resolved fluoroimmunoassay using a tetradentate beta-diketonate europium chelate as a label

A tetradentate beta-diketonate europium fluorescent chelate, 4,4'-bis(1 ",1 ",1 ",2 ",2 ",3 ",3 "-heptafluoro-4 ",6 "-hexanedion-6 "- yl)-chlorosulfo- o-terphenyl(BHHCT)-Eu3+, was used as a label for highly sensitive time-reso lved fluoroimmunoassay of bensulfuron-methyl (BSM). A BSM-BSA (BSA=bovine s erum albumin) conjugate was labeled with BHHCT-Eu3+ and the labeled BSM-BSA conjugate was used for competitive immunoassay. The assay was carried out in a 96-well microtiter plate coated with the anti-BSM monoclonal antibody. The method gives the detection limit of 24 pg/ml, which is one to two orde rs of magnitude lower than those of the conventional HPLC and other methods . The RSD of the present method is less than 10%, and the recovery is in th e range of 90 - 110% for BSM water samples.