Microwave-Assisted Diluted Acid Digestion for Trace Elements Analysis of Black Tea Leaves

Abstract:

A new method for microwave-assisting diluted acid digestion of tea leaves ，The paper calibrated the instrument and measurement process with EPA6020，It determined the content of the trace elements in black tea leaves by microwave digestion and ICP-MS，It analyzed the 16 kinds of trace and Mn et al，were lower than the limited value，elements（V，Cr，Mn，Fe，Co，Ni，Cu，Zn，As，Se，Sr，Ag，Cd，Cs，Ba and Pb） in 8 kinds of blacks tea leaves，besides，It analyzed the trace elements with the method of principal component analysis. Consequently，the concentration of diluted acid was 2.1±0.2 mol/L could replace concentrated acid，the recovery was 90%~110%，RSD was lower than 5%，and the limited detection was lower. The result turned out that the essential elements，including Sr，Fe，Zn but the content of As was more than the limited value.In generally，The centralized distribution of determining values except the samples of Ba，Sr in S1，Se in S6 and Ag in S8. besides，the reported value of Cd was 43.53 times more than the determined value，the determined value of As was 12.53 times more than the addition，It also showed that Pb，Cd，As and Cr were toxic and harmful elements，the content of Pb and Cr were reported value，the result showed that the pollution of As was more serious，Cr was a little pollution，but the Cd was well controlled in the planting，harvesting，processing and transportation. The research also showed that V，Sr，Cr，Ba，Fe，As and Zn were principal component elements. Besides，it made a comprehensive evaluation for 8 kinds of black tea leaves，the result proved that S1 was the best choice.