Spectrophotometric method for the determination of paraquat in water, grain and plant materials

Abstract

A sensitive spectrophotometric method for the determination of paraquat using ascorbic acid (an easily available reducing agent) is described. Paraquat is reduced with ascorbic acid in alkaline solution to give a blue radical ion with an absorbance maximum at 600 nm. Beer's law is obeyed in the range 12–96 µg of paraquat in 10 ml of the final solution (1.2–9.6 ppm). The important analytical parameters and the optimum reaction conditions were evaluated. The method was applied successfully to the determination of paraquat in water, grain and plant materials.