Application of trace element and stable isotope signatures to determine the provenance of tea (Camellia sinensis) samples

The reputation of particular countries, and plantations within those countries, for the production of high quality tea means that these producers can ask a significantly higher price for their specific product than average. This leads to a temptation for unscrupulous producers to fraudulently label their product as coming from one of these areas to take advantage of this higher price. A simple method for the analysis and verification of the country and plantation of origin of tea would provide security to both tea growers and consumers and would largely stamp out this illegal activity. This paper details the use of complimentary organic and inorganic isotope techniques for the analysis of tea samples from Asia. The application of linear discriminant analysis of the isotope ratios and mineral concentrations permitted 97.6% correct classification of the tea samples using the following variables δD, δ13C, 49Ti, 53Cr, 59Co, 60Ni, 65Cu, 71Ga, 85Rb, 88Sr, 89Y, 93Nb, 111Cd, 133Cs, 138Ba, 139La, 140Ce, 141Pr, 153Eu, 203Tl, 208Pb and 209Bi.