Residue Determination of Dimethoate in Leafy Vegetables (Spinach) using RP- HPLC

Residues of Dimethoate present in locally available Spinach varities - Palak : Beta maritima, Vendhai : Trigonella foenumgraecum, Thandan : Amarnathus mangostanus - green and red were determined. The quantification was carried out using RP-HPLC for unprocessed (fresh) and processed (washed, washed and cooked) Spinach samples. The extraction was carried out with benzene. It was found that unprocessed Dimethoate Spinach contains dimethoate residue which is slightly more than the tolerance limit, while the processed sample contains dimethoate residue within the tolerance limit. The washed samples (3 times under ordinary tap water) showed 28-50 % reduction while the cooked samples (boiling for 15 min) shows 58-71 % reduction compared to the unprocessed samples. Hence it can be concluded that in case of greens, it should be washed three times with ordinary water and then cooked (cooked for fifteen minutes) so that the pesticide residue is very much reduced and it will be well within the tolerance limit as specified by EPA (Environmental Protection Agency).