Determination of some toxic and essential trace metals in some medicinal and edible plants of Karachi city

ABSTRACT

Trace metals in eight different medicinal plants commonly available in Karachi namely Azadirachta indica [Neem], Syzygium aromaticum [Clove], Murraya koenigii [Curry Leaves], Trachyspermum ammi [Ajowan], Foeniculum vulgare [Fennal], Brassica oleracea [Cabbage], Brassica rapa [Turnip], and Pipper nigrum [Black pepper] have been quantitatively analyzed using Atomic Absorption Spectroscopy and Flame Photometry. A wet digestion procedure involving the use of H[2]SO[4] [95%] and H[2]O[2] [35%] has been adopted to digest medicinal plants. Nine heavy metals [Cd, Cr, Co, Cu, Fe, Pb, Mn, Ni and Zn] and two alkali metals [K and Na] were chosen on the basis of their effects upon health. In general the order of concentration of toxic metals in medicinal plants was found to follow the order Pb> Ni> Cr> Co> Cd. Sodium and Potassium content was found to be very high in all the samples. Concentration of sodium were recorded to be the highest in roots of Brassica rapa and Murraya koenigii i.e., more than 1000 micro g/g. Postassium concentrations are around 9038 micro g/g in Foeniculum vulgare. Plante samples of Trachyspermum ammi, leaves of Brassica rapa, and Foeniculum vulgare, Brassica oleracea [Cabbage], contained comparatively higher amounts of Fe i.e., > 100 micro g/g. Out of all toxic metals Lead is present at noticeable levels in all the samples that indicates higher soil pollution. Concentrations of Na, K and Mn and Cu are found to be very high in Brassica rapa roots as compared to its leaves while Fe levels are found to be high in leaves