Falcon tubes with screw caps

Briefly, sampling took place between November 2017 and June 2021 throughout Germany. The sampling procedure and geographical distribution of mineral springs have already been described in detail in our previous publications [9 (link),10 (link)]. Beverages were purchased from supermarkets, drinks retailers, petrol stations and kiosks. In total, 990 samples were collected (Figure 1). Ten-milliliter aliquots of the corresponding beverages were placed into polyethylene Falcon tubes with screw caps (Sarstedt, Nuembrecht, Germany). The samples were stored in carton boxes until mineral analysis.

Coffee and tea samples were purchased in their dry form as 250–500 g ground coffee packages and commercially available tea bags, respectively. Coffee and tea infusions were prepared under standardized conditions: 7 g coffee ground was placed in a porcelain filter covered with unbleached filter paper and brewed with 150 mL deionized water at 90 °C. The tea bags (on average 2.1 g/bag; 1.75–3.0 g/bag) were brewed with 250 mL deionized water for 7 min at a starting temperature of 98 °C. Five-milliliter aliquots of the corresponding samples were dispensed into polyethylene Falcon tubes with screw caps (Sarstedt, Nuembrecht, Germany) and stored at −20 °C for multi-element analysis.