P. S. ZAPRJANOVA1, V. R. ANGELOVA2, G. L. BEKJAROV3 and K. I. IVANOV2
1 Institute of Tobacco and Tobacco Products, BG - 4108 Plovdiv, Bulgaria
2 University of Agriculture, Dept. of Chemistry, BG - 4000 Plovdiv, Bulgaria
3 Gardering and Canning Institute, BG - 4000 Plovdiv, Bulgaria
ZAPRJANOVA, P. S., V. R. ANGELOVA, G. L. BEKJAROV and K. I. IVANOV, 2006. AAS and ICP determination of heavy metal content in tobacco. Bulg. J. Agric. Sci, 12: 537-551
There has been carried out a comparative study of the standard methods (dry ashing, acid digestion and microwave digestion) and analysis (ICP - OES and AAS) of tobacco leaves of Burley and Virginia varieties for the determination of Fe, Mn, Cu, Zn, Pb, Cd and Ni. It can be concluded, that both measurement methods (ICP-OES and AAS) provide comparable results with a good agreement and the results of this study are affected in greater extent by the decomposition procedure than by measurement techniques. A careful choice of suitable digestion procedures is critical step in ensuring correct results because even very similar material may exhibit different behavior during the digestion. The use of HNO3 alone does not provide us with good results even with the microwave digestion of tobacco samples. To achieve total decomposition of sample matrices and dissolution of elements, combination of HNO3 and HCI, HF, HCIO4 or H2O2 have to be used. A careful approach should be applied when using dry ashing for sample preparation. The lower temperatures (400 - 450 °C) and the longer heat treatment favor the obtaining of correct results. Taking into consideration the good detection limits, large linear dynamic range and simultaneous multi-element capability it seems that the combination of ICP with microwave digestion procedure is a very rapid and accurate method for analyzing plant materials.