Comparison of certain elemental mounts in black, green, fruit, and herbal teas

The diet is the main source of minerals and trace elements, thus exposure to dietary essential elements has a direct impact on human health. Magnesium is a major component of the bones, but furthermore it influences the nervous system and muscle activity. Therefore its needs must be met via nutrition. There is a non-negligible discrepancy between intake and requirements. So magnesium is often uptaken in form of nutrition supplements. Thus there is still an interest in the amount of magnesium in natural products, where it is supposed to vary. Furthermore other minor elements, such as Zn, Mn and Cu are of concern. Zn is important for the immune function and resistance of the body. Mn also supports immunity and stimulates anti-toxin synthesis. The importance of Copper is based on occurrence in several enzymes. In this study, various commercially available tea powders (sold in bags) of different kinds of tea (black tea, green tea, fruit tea and herbal tea) were analyzed for their content of the elements of interest. After a microwave assisted digestion with nitric acid and water at temperatures up to 220°C, the element concentrations have been measured with ICP-OES (inductively coupled plasma-optical emission spectroscopy) as it is a simultaneous, fast and reliable method with low detection limits. All samples have been prepared in duplicate and were measured in triplicate. The obtained results of all four elements were compared by statistical tests in order to determine statistically significant differences between the tea types.