Preliminary study using trace element concentrations and a chemometrics approach to determine the geographical origin of tea

Abstract

A preliminary study to classify tea by geographical origin using trace metal concentrations was made. Fifteen types of tea from ten different countries were digested using nitric acid. The digests were then analysed for their trace metal contents using either inductively coupled plasma-atomic emission spectrometry for the more concentrated analytes (Al, Ba, Ca, Cu, Fe, La, Mg, Mn, Sr, Ti and Zn) or inductively coupled plasma mass spectrometry for the less concentrated analytes (Cd, Co, Cr, Cs, Hg, La, Li, Nd, Ni, Pb, Pr, Rb, Se, Sn, Ti, V and Zr). The data obtained from these results were then analysed using UNSCRAMBLE, a chemometrics package that incorporates principal component analysis, and by using Matlab 4.2cl High Performance Numeric Computation and Visualisation software. The results of the chemometrics analysis indicated that a distinction between African and Asian and between Chinese and other Asian teas could be made.