Determination of Selected Essential and Non-essential Metals in the Stems and Leaves of <i>Rhamnus prinoides</i> (Gesho)

Abstract

This study was carried out with the objective of determining the quantity of selected essential and nonessential metals; K, Na, Mg, Ca, Cu, Mn, Cr, Cd, Fe and Zn in the leaf and stem of Rhamnus prinoides. Samples were collected from the low-altitude (1500.1670 meters above sea level) and medium-altitude (1670.2000 meters above sea level) areas of Bako Tibe. Wet acid-digestion using a mixture of HNO3, HClO4 and H2O2 for leaf (2.5, 1, 0.5 mL) and for stem (2.5, 1.5, 1 mL) was used. K and Na were analysed using flame photometry, Ca and Mg were determined titrimetrically and the other metals with flame atomic absorption spectrometry (FAAS) after appropriate quality control measures were undertaken to verify and maintain the quality of the data generated. The results of the study showed that the average concentrations determined were ranged from 8855.543 (stem) to 12927.3 (leaf) mg kg-1 for K, 226.214 (leaf) to 308.657 (stem) mg kg-1 for Na, 6144 (stem) to 11120 (leaf) mg kg-1 for Ca, 352.34 (leaf) to 1526.809 (stem) mg kg-1 for Mg, 29.0995 (leaf) to 49.913 (stem) mg kg-1 for Cu, 3.357 (stem) to 13.107 (stem) mg kg-1 for Mn, 1.714 (leaf) to 2.374 (stem) mg kg-1 for Cr, 8.58 (leaf) to 10.73 (stem) mg kg-1 for Fe, 3.483 (leaf) to 18.36 (stem) mg kg-1for Zn and below method detection limit for Cd. The concentrations of the metals were also compared with recommended maximum permissible limits and some international reports; and found to be in a good agreement indicating no exposure risk of using the leaves and stems of Rhamnus prinoides under the current situation.