Determination of essential and toxic elements in herbal teas

Recently, especially among young people, herbal teas have become increasingly common, often associated with specific health benefits, including anti-inflammatory, antioxidant, and slimming effects [1]. Numerous studies link tea consumption to the prevention of many types of cancer, diabetes, and Alzheimer's disease, as well as a boost in immune defenses and a reduction in inflammation and blood cholesterol levels [1]. In Italy, there still needs to be adequate legislation governing the trade, use, and content of chemical contaminants in herbal teas. In particular, some formulations of herbal teas, also due to the introduction of new ingredients such as algae and hemp, can be rich in chemical substances, including toxic metals, which can have various negative effects on the human organism, especially if we consider people in particular conditions, such as pregnant women, breastfeeding women, infancy and the elderly. For example, Al, As, Cd, Cu, Hg, and Pb can be present naturally in soil and water or released due to anthropogenic activities such as mining, agriculture, or industrial processes [2]. Furthermore, the regular intake of herbal teas can significantly contribute to exceeding the recommended daily intake (RDA) limits of some essential elements (Ca, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, and Zn) [3,4]. Hence, there is a need to develop reliable, rapid, and economical analytical methods for determining the elements in these products and carrying out a correct risk estimate, which is necessary to support decision-making processes to protect consumer health. The general objective was to carry out an estimate of the risks associated with the presence of 48 elements (Ag, Al, As, B, Ba, Be, Bi, Ca, Cd, Ce, Co, Cr, Cs, Cu, Dy, Fe, Ga, Hg, K, La, Li, Mg, Mn, Mo, Na, Nb, Nd, Ni, P, Pb, Pr, Rb, Sb, Se, Si, Sn, Sr, Tb, Te, Th, Ti, Tl, U, V, W, Y, Zn, and Zr) in different types of herbal teas identified among those most used in Italy. For this purpose, an analytical methodology for elemental analysis by inductively coupled plasma spectroscopy was developed. The best sample preparation procedure was evaluated using different reagent mixtures and four food standard reference materials (NIST1515, NIST1547, INCT-TL-1, and BCR482). The use of a 3 mL reagent mixture consisting of HNO3 and H2O2, 2:1 (v/v) was found to produce satisfactory results in all cases. This method can be used for routine analysis and food quality control applications. Acknowledgements: This work was funded by the project 2021 RM12117A5D872C39 (Principal Investigator M.L. Astolfi) financed by Sapienza University of Rome. [1] H. Cao, L. Qiao, H. Zhang, J. Chen. Exposure and risk assessment for aluminium and heavy metals in Puerh tea. Sci. Total Environ. 2010, 408(14), 2777-2784. [2] G. Schulzki, B. Nuesslein, H. Sievers. Transition rates of selected metals determined in various types of teas (Camellia sinensis L. Kuntze) and herbal/fruit infusions. Food Chem. 2017, 215, 22-30. [3] A. Szymczycha-Madeja, M. Welna, P. Pohl. Elemental analysis of teas and their infusions by spectrometric methods. Trends Analyt. Chem. 2012, 35, 165-181. [4] T. Karak, F.R. Kutu, J.R. Nath, I. Sonar, R.K. Paul, R.K. Boruah, S. Sanyal, S. Sabhapondit, A.K. Dutta. Micronutrients (B, Co, Cu, Fe, Mn, Mo, and Zn) content in made tea (Camellia sinensis L.) and tea infusion with health prospect: A critical review. Crit. Rev. Food Sci. Nutr. 2017, 57(14), 2996-3034.