Identification of Volatile Components in Tea Infusions by Headspace-Programmed Temperature Vaporization-Gas Chromatography-Mass Spectrometry (HS-PTV-GC-MS) with Chemometrics

In this work, the two-step headspace (HS) technique was applied to determine the actual volatile compositions of tea infusions. In order to eliminate the influence of water vapor to the gas chromatography-mass spectrometry (GC-MS) analysis and enable the capability to determine the volatile compounds in water base samples, a programed temperature vaporizer (PTV) was employed for the additional pre-concentration of thee analytes. While using the reported method, the volatile compounds were retained by the absorbent packed in the PTV, while the water vapor was directly removed through the purge valve. Then the retained volatile compounds were splitlessly injected into the GC column, which means that very low detection limits were achieved with the newly developed method. The obtained results demonstrated that the reported protocol possessed excellent repeatability and stability for volatile compound determination, and a total of 94 volatile compounds were identified from 28 teas. Multivariate data analysis was performed to obtain insights into the relationship between volatile compounds composition of the teas and their types. The volatiles composition of tea was shown to be closely related to the processing techniques adopted. Furthermore, the characteristic volatile compounds of each tea type were also illustrated. All of the results demonstrated that the presented method is a reliable approach to analyze and discriminate various beverages.