A method has been developed for the direct determination of paraquat and diquat in water samples. No sample preparation was required and analysis was done using high performance liquid chromatography coupled with ionspray tandem mass spectrometry. Heptafluorobutyric acid was used as the ion-pair agent. Further improvements in this method included the incorporation of an internal standard (caffeine). Using this method, detection limits of 5 and 1 µg/L were obtained for paraquat and diquat respectively. Recoveries were consistently > 90% with relative standard deviations of < 10% over the concentration range 5-100 µg/L. To our knowledge, this method is the first application of ionspray tandem mass spectrometry, and the first to use heptafluorobutyric acid as an ion-pair reagent, for the analysis of paraquat and diquat.

No abstract