Investigation Of Metals In Ethiopian Tobacco Leaves And Processed Tobacco

Samples of tobacco leaves (Virginia type) were collected from two different regions ofrnEthiopia (Bilatte and Shoa Robit) which are the only places where this type of tobacco isrnharvested. The other three processed tobacco samples were collected from tobaccornmanufacturing factory in Addis Ababa, Ethiopia. After collection of the representativernamounts of samples, and samples pretreatment, different digestion procedures were testedrnby varying reagent volumes, time of digestion, temperature of digestion, and amount ofrnthe sample to develop a procedure that consume less reagent volume, short digestionrntime, low temperature of digestion and smaller mass of the sample. The optimalrnprocedure required 3:30 hours and consumes 3 mL HNO3 (69-72 %) and 3 mL HClO4rn(70 %) to completely digest 0.5 g of both tobacco leaves and processed tobacco samples.rnThe accuracy of the optimized procedure was evaluated by analyzing the digest of thernspiked samples with standard solution. Recoveries of the spiked samples varied fromrn88.3% to 104.3% and 91.7% to 107% for leaves and processed tobacco, respectively.rnConcentrations of metals in the samples; (Cd, Cr, Cu, Ni, Pb and Zn) were analyzed byrnflame atomic absorption spectrometer employing a four point external calibration curve.rnThe observed average metals concentrations were (mean ± ts/N1/2, μg/g at 95% CL andrnN=9): Cu (4.38 ± 0.11), Zn (53.7 ± 0.96), Cd (1.2 ± 0.05) in tobacco leaves collectedrnfrom Bilatte; Cu (7.3± 0.19), Ni (1.9 ± 0.08), Cd (1.3 ± 0.04), Cr (1.45 ± 0.11), Zn (33.15rn±1.9) in leaves collected from Shoa Robit; Cu (9.8 ± 0.04), Ni (2.35 ± 0.19) Cd (1.45 ±rn0.023), Cr (1.65 ± 0.08), Zn (101.2 ± 0.4) in processed tobacco leaves originated fromrnBilatte; Cu (12.8 ± 0.11) Ni (2.2 ± 0.05) Cd (1.9 ± 0.05), Cr (1.75 ± 0 .08), Zn (83.75 ± 0rn.4) in processed tobacco leaves originated from Shoa Robit; Cu (8.95 ± 0.31), Cd (1.55 ±rn0.02), 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; Crrnand Ni in tobacco leaves from Bilatte (0.05 and 0.04 mg/L respectively). This studyrnshowed that the metal contents of tobacco leaves varied with the geographical origin inrnwhich the tobacco plant grows, and the metal contents of processed tobacco were higherrnthan the corresponding leaves. The levels of metals in Ethiopian tobacco are comparablernwith that of other countries.rnKey words: Tobacco leaves, Processed tobacco, Trace metals, FAAS

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