Geographical tracing of Xihu Longjing tea using high performance liquid chromatography.

Xihu Longjing tea (XHLJ) is one of the most famous green tea in China. Due to its high price, some inauthentic XHLJ from other tea producing areas appear on the market and hurt the interests of customers and producers. High-performance liquid chromatography (HPLC) combined with the principal component analysis (PCA) and linear discriminant analysis (LDA) methods were applied to the geographical tracing of XHLJ from two other types of Longjing teas and a non-Longjing flatten-shaped tea (non-LJ). The chromatograms of the tea samples from four different regions were highly similar. It was difficult to classify 4 types of teas directly by PCA. However, high total accuracy rates of 94.8% and 87.6% for the training and test set were achieved for distinguishing XHLJ from the other three types of tea by stepwise discriminant analysis. The identification accuracy of XHLJ from non-LJ was the highest, suggesting geographical distance might play an important role in this process. In summary, a combination of chromatographic chemical fingerprints with LDA provides a simple and rapid approach for the identification of XHLJ from other teas.