Abstract

Yerba mate is a native plant found in subtropical South American regions (Paraguay, Brazil, Argentina, and Uruguay), where is commonly consumed as an infusion and worldwide as tea. The safety of yerba mate involves continuous monitoring of arsenic and cadmium levels, and the product's labeling also includes measurement of nutrient content such as sodium and phosphorus. The Supplementary Comparison and parallel Pilot Study SIM.QM-S11 & P25 Elements in Yerba mate (Ilex paraguariensis) covered arsenic (0.0575 mg/kg), cadmium (0.7526 mg/kg), sodium (33.46 mg/kg) and phosphorus (1.738 mg/g). The last CCQM or RMO key comparison / supplementary comparison of elements in plants matrices was organized by the Government Laboratory, Hong Kong, China (GLHK) in 2011 and results were published in 2013 (CCQM-K89 Trace and essential elements in Herba Ecliptae, including arsenic, calcium, cadmium, lead and zinc). Hence, it was timely to organize another comparison that could cover different measurands in high silica content matrix. Moreover, it enabled National Metrology Institutes / Designated Institutes (NMIs/DIs) that did not participate in previous comparisons to demonstrate their measurement competencies. Evidence of successful participation in formal, relevant international comparisons is needed to document calibration and measurement capability claims (CMCs) made by national metrology institutes (NMIs) and designated institutes (DIs). Fifteen National Metrology Institutes and Designated Institutes participated in the Supplementary Comparison SIM.QM-S11 (Elements in Yerba mate (Ilex paraguariensis)). Participants were asked to assess the mass fractions of arsenic, cadmium, and sodium in mg/kg, along with the mass fraction of phosphorus in mg/g on a dry mass basis in yerba mate matrix. Results of all participating NMIs/DIs were evaluated against the supplementary comparison reference value (SCRV). The SCRV and associated uncertainty were determined from results of NMIs/DIs that participated in the supplementary comparison using methods with demonstrated metrological traceability. Most participating NMIs/DIs employed microwave-assisted acid digestion for sample preparation. Inductively coupled plasma mass spectrometry (ICP-MS), sector field ICP-MS (SF-ICP-MS) and inductively coupled plasma atomic emission spectroscopy (ICP-OES) were the most commonly used instrumental techniques. Successful participation in SIM.QM-S11 demonstrates measurement capabilities in determining mass fraction of transition elements (except Hg), alkali and alkaline earth, non-metals (exp: C, N, and O) and metalloids/ semi-metals in mass fraction range from 0.02 mg/kg to 5000 mg/kg in high silica content matrixes. © 2025 Institute of Physics. All rights reserved.