A rapid method for the emergency analysis of paraquat in plasma using a second derivative spectroscopy.

A rapid method for the analysis of paraquat in plasma of poisoned patients is described. The dithionite colour reaction is used to detect paraquat, and matrix interference is eliminated by the use of a chemical deproteinization technique followed by second derivative spectroscopy of the reaction mixture. The method was compared with an established procedure using ion-pair extraction followed by dithionite reduction. Sensitivity and precision were comparable and the correlation in patients' plasma was good. The proposed direct method is rapid and suitable for emergency use in the management of patients poisoned with paraquat.