SPECTROPHOTOMETRIC METHOD FOR DETERMINATION OF PARAQUAT IN FOOD AND BIOLOGICAL SAMPLES

A sensitive spectrophotometric method was developed for determination of paraquat, a widely used herbicide, paraquat was reduced with glucos e in an alkaline medium, and the blue radical ion obtained was measure d at 600 nm. Beer's law was obeyed at 0.1-1.2 ppm paraquat, The molar absorptivity was 1.26 x 10(5) L mol(-1) cm(-1). The standard deviation and relative standard deviation were +/- 0.007 and 2.0%, respectively , for 5 mu g paraquat/10 mL analyzed over 7 days. The method was free from interference by other commonly used pesticides and metal ions, Th e method may be used to the determine paraquat in plants, fruits, grai ns, water, blood, and urine.