DETERMINATION OF TRIASULFURON IN SOIL BY MONOCLONAL ANTIBODY-BASED ENZYME-IMMUNOASSAY

A panel of monoclonal antibodies (MAbs) specific to triasulfuron was obtained by using two different hapten-protein conjugates as immunogens. MAbs generated with a simple hapten corresponding only to the chloroethoxy sulfonamide moiety of triasulfuron with an additional succinic acid spacer showed much higher affinity for triasulfuron as compared to those obtained with a hapten consisting of the complete molecule with an aminoalkyl spacer attached to the triazine ring. The cross-reactivity of the MAbs was limited to only a few structurally related compounds as determined by competitive ELISA. Most of the MAbs cross-reacted with the phenylhydroxylated degradation products of triasulfuron, whereas a few others cross-reacted with cinosulfuron and a fluoroethylthio analogue of triasulfuron. The competitive enzyme immunoassay based on these MAbs detected triasulfuron in aqueous media ranging from 0.01 to 1-mu-g/L. The ELISA was tested on fortified soil samples. The extraction procedure was optimized to reduce the soil matrix effects to a minimal level, allowing the detection of triasulfuron down to 0.1-mu-g/kg of soil.