Estimation of diafenthiuron residues in cabbage by hplc and confirmation by lc-ms-ms

Diafenthiuron, 1-tert-butyl-3-(2,6-diisopropyl-4-phenoxyphenyl) thiourea, a broad spectrum insecticide cum acaricide belonging to thiourea group, has been found effective in managing sucking pests and mites. The persistence pattern of its Polo 50% WP on cabbage following three applications at 300 and 600 g a.i. ha⁻¹ at an interval of 10 d, is reported. Residues were estimated by HPLC and confirmed by LC-MS-MS. The average initial deposits were 0.60 and 1.27 mg kg⁻¹ on the cabbage heads following its third application at single and double the recommended dosages, respectively. Half-life periods were found to be 1.88 and 2.15 d at the two application rates, respectively. The residues reduced to below its limit of quantification of 0.05 mg kg⁻¹ after 7 and 10 d, at the single and the double dosages respectively.