Comprehensive multielement profiling and statistical analysis of tea samples available in the Italian market: Influence of geographic origin, brewing time and preparation method

This study characterized the multielement profiles of commercial black teas in the Italian market, assessing how geographical origin and tea type affect leaf composition, and how origin, brewing time, and preparation method influence elemental transfer to infusions. Nineteen elements were quantified using Inductively Coupled Plasma Mass Spectrometry (ICP-MS) following sample pretreatment via microwave-assisted acid digestion with HNO3/ H2O2. The analytical method was successfully validated, showing high accuracy with recovery rates of 87–105% and limits of detection (LOD) ranging from 0.0003 to 0.0015 μg/L. In tea leaves, K was the most abundant element (averaging 1479.6 mg/kg). Chinese teas showed higher Al, Mg, Mn, Cu, Ni, Pb, Co, As, and Cd in leaves (e.g., Al up to 212.2 μg/kg and Pb up to 123.1 ng/kg). Subsequent infusions, prepared for 3, 5, or 8 min with or without a tea bag, revealed that Cu and Pb effectively distinguished geographical origin (following the gradient Argentina < India < China). Furthermore, caffeinated teas released significantly higher levels of Pb and Cd (averaging 0.529 ng/L and 0.032 ng/L, respectively, after 5 min of brewing with a bag), while decaffeinated samples were characterized by higher levels of Cr and Sr (averaging 0.89 ng/L and 0.017 ng/L, respectively). Elemental transfer varied: K, As, Na, Ni, and Zn were highly extracted (>88%), whereas Fe, Sr, Cr, Cu, Pb, and Cd were minimally transferred (<16%). Brewing time and tea format affected kinetics, with loose tea releasing elements faster. Dietary assessment confirmed negligible contribution to essential elements and safe levels of toxic elements. Although bounded by a limited sample size and lack of proprietary industrial processing details, this integrated approach provides a highly comprehensive framework for assessing elemental dynamics, transfer behaviors, and consumer safety in tea beverages.