Investigation of Metals in Ethiopian Tobacco Leaves and Processed Tobacco

No Thumbnail Available



Journal Title

Journal ISSN

Volume Title


Addis Ababa Universty


Samples of tobacco leaves (Virginia type) were collected from two different regions of Ethiopia (Bilatte and Shoa Robit) which are the only places where this type of tobacco is harvested. The other three processed tobacco samples were collected from tobacco manufacturing factory in Addis Ababa, Ethiopia. After collection of the representative amounts of samples, and samples pretreatment, different digestion procedures were tested by varying reagent volumes, time of digestion, temperature of digestion, and amount of the sample to develop a procedure that consume less reagent volume, short digestion time, low temperature of digestion and smaller mass of the sample. The optimal procedure required 3:30 hours and consumes 3 mL HNO3 (69-72 %) and 3 mL HClO4 (70 %) to completely digest 0.5 g of both tobacco leaves and processed tobacco samples. The accuracy of the optimized procedure was evaluated by analyzing the digest of the spiked samples with standard solution. Recoveries of the spiked samples varied from 88.3% to 104.3% and 91.7% to 107% for leaves and processed tobacco, respectively. Concentrations of metals in the samples; (Cd, Cr, Cu, Ni, Pb and Zn) were analyzed by flame atomic absorption spectrometer employing a four point external calibration curve. The observed average metals concentrations were (mean ± ts/N1/2, μg/g at 95% CL and N=9): Cu (4.38 ± 0.11), Zn (53.7 ± 0.96), Cd (1.2 ± 0.05) in tobacco leaves collected from Bilatte; Cu (7.3± 0.19), Ni (1.9 ± 0.08), Cd (1.3 ± 0.04), Cr (1.45 ± 0.11), Zn (33.15 ±1.9) in leaves collected from Shoa Robit; Cu (9.8 ± 0.04), Ni (2.35 ± 0.19) Cd (1.45 ± 0.023), Cr (1.65 ± 0.08), Zn (101.2 ± 0.4) in processed tobacco leaves originated from Bilatte; Cu (12.8 ± 0.11) Ni (2.2 ± 0.05) Cd (1.9 ± 0.05), Cr (1.75 ± 0 .08), Zn (83.75 ± 0 .4) in processed tobacco leaves originated from Shoa Robit; Cu (8.95 ± 0.31), Cd (1.55 ± 0.02), Cr (1.62 ± 0.11), Ni (4.7 ± 0.04), Zn (79.3 ± 0.77) in Nyala. The Concentration of Pb was lower than detection limit of the instrument (0.1 mg/L) in all tobacco samples; Cr and Ni in tobacco leaves from Bilatte (0.05 and 0.04 mg/L respectively). This study showed that the metal contents of tobacco leaves varied with the geographical origin in which the tobacco plant grows, and the metal contents of processed tobacco were higher than the corresponding leaves. The levels of metals in Ethiopian tobacco are comparable with that of other countries. Key words: Tobacco leaves, Processed tobacco, Trace metals, FAAS



Tobacco leaves; Processed tobacco; Trace metals; FAAS