Simple detection method for paraquat dichloride in various matrices of cotton and sugarcane using liquid chromatography mass spectrometry

Field trials were conducted to determine residues of paraquat dichloride in cotton and sugarcane at harvest time. Paraquat dichloride was sprayed on weeds at two to three leaves stage at doses of 480 and 960 g/ha. Samples collected at 87 and 102 days after herbicide application in cotton and 199 and 341 days after herbicide application in sugarcane were subjected to residue analysis by employing modified QuEChERS method. Recovery studies were conducted to determine the accuracy of method by spiking each matrix with a known concentration of paraquat dichloride. A satisfactory recovery rate of 70 to 120% and RSD < 20% were obtained in all the matrices. In harvest time samples of cotton (87 and 102 DAT) and sugarcane (199 and 341 DAT) matrices analysed, paraquat dichloride residues were less than the limit of quantification (0.05 mg/kg).