Ultrasensitive quantitative determination of paraquat: application to river, ground, and drinking water analysis in an agricultural area

The water specimens were collected from wells and irrigation ditches in the agricultural area to the south of Milan and from Olona River and Mantua Lake and analyzed for paraquat detection. The assay was performed using a specific polyclonal antibody raised in sheep and rabbit anti-sheep IgG conjugated with a chelating molecule 4,7-bis(chlorosulfophenyl)-1,10-phenanthroline-2,9-dicarboxylic acid complexed with Eu3+ as a fluorescent marker. Bovine serum albumin conjugated with 5-(1‘-methyl[4,4‘]bipyridinyl-1-yl)pentanoic acid was used in solid phase preparation. The sensitivity achieved was 20 ng L-1. The recovery in samples spiked with three different PQ concentrations was between 88 and 108%. Keywords: Paraquat; bipyridylium herbicides; immunoassay; europium chelate; time-resolved fluorescence