Flow injection potentiometric determination of paraquat in formulations and biological samples

A flow injection potentiometric method for the rapid determination of paraq uat in herbicide formulations and biological samples is described. It is ba sed on the utilization of a flow-through potentiometric detector containing polyvinyl chloride-immobilised octamethylcyclotetrasiloxane, a lipophilic plasticizer (tetra-n-undecyl 3,3',4,4'-benzophenone tetracarboxylate) and m embrane additive potassium tetrakis(4-chlorophenyl)borate. The detector was minimally interfered by the presence of constituents such as Na+, K+, Ca2, Mg2+, glucose, urea, lactic and citric acids at physiological levels, res pectively. Good correlation between results of the proposed method and HPLC for the formulation samples was found, while results for the determination of paraquat in biological samples such as urine, vomitus and stomach washo ut was less satisfactory. (C) 1998 Elsevier Science B.V. All rights reserve d.