Overview
Koláčková and colleagues analysed three commercial matcha powders bought in the Czech Republic for minerals and trace elements before and after in vitro enzymatic digestion, and measured how much leached into ice teas made three ways. Mercury was quantified in every powder, while cadmium and lead stayed below the 1.00 µg/g quantification limit in powders and ice teas. The PDF is the Elsevier accepted “Journal Pre-proof” version.
Key numbers
- Mercury in matcha powder: 240±10, 310±20 and 410±30 ng/g dry weight for the three products (Table 5).
- Cadmium and lead in all powders: ”< 1.00” µg/g, LOQ 1.00 µg/g (Table 5).
- Mercury in the non-digestible residue fell to 36.1 to 40.8 ng/g (Table 5).
- Mercury leached into ice tea: 110 to 170 ng per g of matcha, leaching values 36 to 51% depending on method (Table 6).
Methods (brief)
Microwave digestion with nitric acid and hydrogen peroxide; flame AAS for Na, Mg, K, Ca, Mn, Fe, Zn and Se, electrothermal AAS for cadmium and lead, and a direct mercury analyzer (AMA-254) for mercury. Reference materials INCT-TL-1 (tea leaves) and IAEA-336 (lichen) gave recoveries of 88 to 109%. Each value is the mean of six replicate measurements on one product.
Evidence Fitness
Only three products, each a single lot, so this is a small market snapshot rather than a survey. Mercury data are well supported by a dedicated analyzer; the cadmium and lead LOQ of 1.00 µg/g is high, so the non-detects do not rule out levels typical of tea. Ice tea results are expressed per gram of matcha powder, not per liter of drink.