Determination of Selected Heavy Metals in Leaves and Petiole of Parts of Croton Macrostachyus Collected from Hidabu Abote, North Shoa, Oromia Region, Ethiopia Teshome Tolcha

Abstract: In this study, the level of Ca, Mg, Fe, Zn, Ni, Cr, Pb and Cd in leaves and petiole parts of Croton macrostachyus were determined using flame atomic absorption spectroscopy. A wet digestion method was used to digest a 0.5 g of both samples with 2 mL of HClO4 (70%) and 2 mL of HNO3 (69%) for a digestion time of 2.25 h at a digestion temperature of 270 oC. A series of solution were prepared from stock solution to construct calibration curves for each metal investigated. The recovery analysis was made by spiking 0.5 g of leave and petiole parts of Croton macrostachyus samples at concentration levels of 1565 g/g of Ca, 992 g/g of Mg, 116 g/g of Fe, 12 g/g of Zn, 1.75 g/g of Pb, 1.08 g/g of Cd, 1.68 g/g of Ni and 1.84 g/g of Cr. The method offers a good regression coefficients (0.9998-0.9999), limit of detection (0.03-4.23 g/g), and limit ofquantification (0.1-14.1g/g). The percentage recovery of target analytes were in the ranges of 95.5%-104% which is in agreement with accepted ranges. The concentration of Ca, Mg, Fe, Zn, Pb, Cd, Ni and Cr in leaves of Croton macrostachyus, were 12,137, 5,038, 592, 65.3, 2.86, 1.26, 2.73 and 2.38 µg/g, respectively. Similarly, the concentration of Ca, Mg, Fe, Zn, Pb, Cd, Ni and Cr in petiole of Croton macrostachyus 10,815, 4,251, 482, 57.2, 2.64, 1.12, 2.74 and 2.21 µg/g, correspondingly. The amount of Fe, Zn, Cd, Ni and Cr were above the tolerable limit of WHO for herbal medicine.