Study on the Content of Rubidium in Tea

Objective Analysis of rubidium (Rb) in tea was conducted to provide information currently lacking for research and technical needs.

Method Dry matter, total ash, and water-insoluble ash in 36 tea specimens were determined by the national standard analytical methods. Rb in the ash was measured using energy dispersive X-ray fluorescence spectroscopy (EDXRF) with peaks in the spectrum analyzed. Solubility of Rb in tea were determined, and dietary intake from 10 g·d⁻¹ of tea drinking calculated.

Result The 36 tea specimens that showed three top EDXRF peaks to be Rb amounted to significant 30.6%, 27.8%, and 30.6% of all. Hence, Rb ought to be viewed as an important mineral in studying teas. The extraction rates of Rb in the sampled teas ranged from 87.83% to 99.90% with a content between 18.85 mg·kg⁻¹ and 417.24 mg·kg⁻¹. The difference between the medium-high and medium-low Rb contents of the teas was significant. Those among the medium-high, medium, and low contents in the teas of same geographic origin were significant as well. Based on daily consumption of 10 g, the Rb intakes from the variety teas were estimated to be 0.18-4.07 mg·d⁻¹.

Conclusion The 36 varieties of teas showed significant Rb peaks on EDXRF spectrum indicating a deserved attention of the trace element in studying teas. The generally highly soluble Rb varied significantly in content by tea types and of different production areas.