A SIMPLE HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY IONSPRAY TANDEM MASS-SPECTROMETRY METHOD FOR THE DIRECT DETERMINATION OF PARAQUAT AND DIQUAT IN WATER

A method has been developed for the direct determination of paraquat a nd diquat in water samples. No sample preparation was required and ana lysis was done using high performance liquid chromatography coupled,vi th ionspray tandem mass spectrometry, Heptafluorobutyric acid was used as the ion-pair agent. Further improvements in this method included t he incorporation of an internal standard (caffeine). Using this method , detection limits of 5 and 1 mu g/L were obtained for paraquat and di quat respectively, Recoveries were consistently > 90% with relative st andard deviations of < 10% over the concentration range 5-100 mu g/L. To our knowledge, this method is the first application of ionspray tan dem mass spectrometry, and the first to use heptafluorobutyric acid as an ion-pair reagent, for the analysis of paraquat and diquat. (C) 199 7 by John Wiley & Sons, Ltd.