Gas-liquid chromatographic determination of S-[(5-methoxy-2-oxo-1,3,4-thiadiazol-3(2H)-yl)-methyl]O,O-dimethyl phosphorodithioate (Supracide) and its monoxone metabolite in safflower seed, meal, and oil.

A gas-liquid chromatographic (GLC) method for determining residues of the inseticide-acaricide Supracide (S-[5-methoxy-2-oxo-1,3,4-thiadiazol-3(2H)-yl)-methyl]O,O-dimethyl phosphorodithioate) and its monoxone metabolite in safflower seed, meal, and oil is presented. Supracide and its monoxone metabolite are separated by partitioning with acetonitrile-sodium sulfate and petroleum ether. The petroleum ether fraction containing the Supracide is extracted with acetonitrile and further cleaned up on Florisil column before determination by GLC, flame photometric detection (FPD). The monoxone metabolite is partitioned from the acetonitrile-sodium sulfate fraction with chloroform and cleaned up on a Florisil column before GLC/FPD. Average Supracide recoveries were 86, 82.5, and 92%, and average Supracide monoxone recoveries were 85.7, 81.5, and 89%, in seed, meal, and oil, respectively. The limit of detection was 0.005 ppm for both compounds on all tissues analyzed.