14C-Prothiofos Residues in the Presence of Deltamethrin and Dimilin Pesticides in Cotton Seeds and Oils, Removal of Prothiofos Residues in Oils and Bioavailability of its Bound Residues to Rats

Abstract

Ethyl-1-14C-prothiofos and some of its degradation products have been prepared for the present investigation. Cotton plants were treated with 14C-prohiofos alone and in presence of deltamethrin and dimilin pesticides under conditions simulating local agricultural practice. 14C-residues in seeds were determined at harvest time about 75% of 14C-activity was associated with oil. The ethanol soluble 14C-residues accounted for 6% of the total seed residues after further seeds extraction, while the cake contained about 18.5% of the total residues in case of prothiofos only. The bound residues increased in presence of deltamethrin and dimilin pesticides and amounted to 30% and 34% of the total residues, respectively. About 89% of the 14C-activity in the crude oil could be eliminated by simulated commercial processes locally used for oil refining. Chromatographic analysis of cotton oil extracts (acetonitrile layer) revealed the presence prothiofos oxon, O-ethyl phosphorothioate, O-ethyl S-propyl phosphorothioate, des-propylthio prothiofos, O-ethyl phosphoric acid as the main degradation products, besides to one unknown compound in addition to the parent compound, in case of prothiofos alone. The same degradation products are found in case of prothiofos and deltamethrin and prohiofos and dimilin except compounds O-ethyl S-propyl phosphorothioate and des-propylthio prothiofos. Chromatographic analysis of ethanol extract revealed the presence of O-ethyl phosphorothioate, despropylthio prothiofos and O-ethyl phosphoric acid as free metabolites. The conjugated metabolite was liberated by acid hydrolysis and identified as 2,4-dichlorophenole which was detected by color. When rats were fed the extracted cake for 72 hours, the bound residues were found to be bioavailable. The main excretion route was via the expired air (49%), while the 14C-residues excreted in urine and feces were (34% and 9.7%), respectively. The radioactivity detected among various organs accounted to 6.1%. Chromatographic analysis of urine was determined.