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LEVEL OF HEAVY METALS IN YAM, CASSAVA AND COCOYAM TUBERS IN NIGER DELTA NIGERIA – A SURVEY

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Abstract

A total of seven heavy metals, Pb, Cd, Zn, Fe, Ni, Cu, Mn, Na, were determined in cassava, yam and cocoyam using atomic absorption spectrophotometer model schimadzu AA 6701 in airacetylene flame. The samples were cut, peeled, washed, sliced very light, air dried and ground into powder. 5g of the powered samples were ashed, digested using 2ml of 36.5g/dm Hydrochloric acid, 2ml conctrioxonitrate (V) acid and distilled water, to remove all the organic matters and leave behind the trace metals. These Endings showed that some metals like Fe (16.23mg/kg in yam), 18.26mg/kg in cassava, 31.36 mg/kg in cocoyam and Zn, 19.77 mg/kg m coco yam have higher values compared with W.H.O standard. The most toxic ones, lead