Comparison of different digestion methods of green and black tea at the Sarajevo market for the determination of the heavy metal content

The content of Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn was determined in commercially available black and green tea from Sarajevo market. The concentrations of metals in tea infusion and solutions prepared by applying four digestion methods were determined by using FAAS. The results show that the highest concentration of total metals was obtained after acid digestion in an autoclave. The concentration of metals soluble in water obtained in tea infusion does not exceed maximum allowed values provided by WHO (Guidelines for drinking-water quality, World Health Organization, Geneva, 2011). Among the investigated metals Mn was the highest and ranged from 286 to 334 μg g−1 in tea infusion of green and black tea, respectively, to 1,078 and 1,528 μg g−1 total content of Mn in green and black tea, respectively. The concentration of heavy metals in water extracts of tea was distinctly low in comparison with the total content. The concentrations of Cd and Pb were under the determination limit using FAAS. The total content of all determined metals was higher in black tea than in green tea.