Persistence and dissipation kinetics of phorate in the soil of sugarcane ecosystem

An experiment was conducted to determine persistence and dissipation kinetics of phorate in sugarcane grown soil under South Gujarat condition. The experimental plots were subjected to application of phorate 10G (1.5 kg a.i./ha) at the time of planting and 60 days after planting of sugarcane. The soil samples were periodically collected at 0 (2 hrs.), 1, 3, 5, 10, 20, 30, 60 and 90 days after last application of phorate. Prior to analysis, acetonitrile based extraction and dispersive clean-up approach adopted to quantify the residues of phorate and its metabolites with LC-MS/MS from soil, sugarcane leaves and juice were verified on method performance verification parameters. The analytical method was accurate, sensitive and precise enough as per SANTE guideline. Residues of phorate and total phorate (phorate + metabolites i.e phorate sulfone and phorate sulfoxide) were observed upto 30 days after application and reached below quantification level at 60 days after application. Phorate and total phorate followed the second order dissipation kinetics in sugarcane grown soil. However, sugarcane leaves and juice contains residues of phorate and its metabolites BQL which are well within the safety limit of MRL.