Evaluation of metal content in tea samples commercialized in sachets using multivariate data analysis techniques

Tea is a beverage consumed all over the world, and, besides the very pleasant taste, it has substances in its composition that can lead to various beneficial effects to human health. However, although teas have essential elements in their composition, they can also be contaminated with metals from the soil, air, and equipment used in their production. In this study, eight metals (Ca, Cu, Fe, Mg, Mn, Zn, Na and K) were determined in tea samples commercialized in sachets using flame atomic spectrometry (absorption and emission) after acid decomposition in a digestion block. The concentration of the analyzed metals varied as follows (in mg kg(-1)): Ca (1856.3-10,012), Cu (2.014-14.90), Fe (43.94-532.2), Mg (739.9-2237), Mn (26.95-946.3), Zn (12.05-41.84), Na (167.7-4322) and K (5089.1-14,334). The generated data were statistically analyzed using the following multivariate analysis tools: Principal Component Analysis, Hierarchical Cluster Analysis and Kohonen self-organizing maps. The multivariate analysis classified the different tea samples into well defined groups according to flavor, based on the mineral composition of eight quantified elements.