ABSTRACT

The metod of the atomic emission spectrometry with an excitation in the inductively coupled plasma ICP-AES has been applied to the simultaneous analysis of the elements: Al, Cd, Cr, Cu, Fe, Li, Mg, Mn, Ni, P, Pb, S, Sr and V in the tobacco leaves samples CTA-OTL-1. The spectrometric analyses have been carried out on the emission spectrometer Spectroflame ICP M. About 300 mg of the sample and 1 cm³ of the concentrated HN0₃ acid have been sealed in the quartz tube and mineralized by the pressure method. Since the ICP-AES technique is the most suitable to the direct analysis of the solutions, the main problem to solve was a mineralization of the sample. An application of the HN0₃ acid alone did not give satisfactory results - unsolved residue remained. As a consequence the results for Mg, Ni, Pb were too low, whereas for the Al - nearly twice lower than the respective values given in the sample reference data. It has been observed that an addition of the conc. HF acid helps to dissolve the residue and, consequently, the optimalization of the mineralization proces in the presence of the HN0₃-HF mixture has been carried out. The results show that the appropriate amount of the HF acid to be added is 0.25 cm³. The other methods of mineralization using various mixtures of acids did not give good results. Only HN0₃-HF mixture used in appropriate proportions give results in agreement with provided sample characteristics. The samples after mineralization have been diluted with redestilled water mineralization have been diluted with redestilled water up to 5 cm³. Since the level of concentration of the investigated elements has been very dilTerent - the direct determination has been carried out only with respect to Cd, Cr, Ni, Pb and V elements. In order to determine the concentration of the Al, Cu, Fe, Li, Mg, Mn, P, S and Sr the original solution has been diluted ten limes i.e. from 1 cm³ to 10 cm³. This method is the most suitable to the analysis of the various powdered materials of plant origin.