Abstract:
This study was aimed at quantifying the levels of some known pesticide residues in some samples of dioscorea rotundata from Anambra, Benue and Ebonyi States of Nigeria. This study also investigated the effect of boiling on the levels of the pesticide residues present in the raw samples. The pesticide residues were quantified using Gas Chromatography coupled to an Electron Capturing Detector and a total of ten (10) pesticide residues were identified. The proximate composition of the different D.rotundata samples were investigated. Abakiliki raw yam sample had the highest fibre (1.74%), fat (0.37%) and ash (3.52%) content while Benue raw yam sample had the highest carbohydrate (88.89%) and moisture content (5.15%) and Onitsha raw yam sample had the highest protein content (3.38%). Organochlorines were the most abundant of the pesticide in the three yam samples. Out of the 10 pesticide residues identified, 6 were organochlorines namely: aldrin, heptachlor, t-nonachlor, g-chlordane, pDDE and endosulfan. Isopropylamine was the only quantified organo phosphate herbicide detected in the three yam samples while 4,4-bipyridinum dichloride (paraquat) was the only herbicide of the pyridyl family detected. There was reduction in the pesticide residue levels in the three boiled samples compared to their raw samples. Isopropylamine, pDDE and dichlorobiphenyl had the lowest residual levels in the three samples while t-nonahlor had the highest residual concentration in the Benue (1.992 µg/g) and Onitsha (1.115 µg/g) yam samples and heptachlor had the highest pesticide residue in the Abakiliki (0.540 µg/g) yam sample1s.
