Variations in the mineral composition and heavy metals content of Moringa oleifera
The parts of Moringa oleifera were assessed for mineral composition and some heavy metal contents in this study, which included Ca, Mg, K, Na, Mn, Fe, Zn, Co, Se, Pb and Cd. Parts of the plant were obtained from Badagry in Lagos State, Nigeria. The samples were digested with HNO3 and analysed for the mineral element content using atomic absorption spectrophotometer. The observed mean concentrations of the mineral elements were 26000, 643, 8210, 2980, 69.9, 169 and 15.3 mg/kg for Ca, Mg, K, Na, Mn, Fe and Zn, respectively. Co and Se, and the heavy metals Pb and Cd were not detected. There seemed to be no significant differences in the overall levels of the mineral elements in the different parts (P > 0.05). However, the observations showed that there were strong correlations between the levels of the elements in stem bark and root bark, stem bark and leaf, stem wood and pod, stem wood and seed, root bark and leaf, and pod and seed (P < 0.01); and between stem bark androot wood, root wood and root bark, and root wood and leaf (P < 0.05).
Key words: Moringa oleifera, mineral composition, heavy metals.