Abstract: A method of developing tea reference materials (RMs) to be used in tea grading based on fingerprint classification was established in this paper, and three grades (120 samples, 50 g each) of Xinyang Maojian tea certified reference materials (CRMs) were developed. Tea infusion samples were prepared according to the national standard, and then analyzed by HPLC for flavor ingredients. A newly improved extent similarity method was used for calculation of fingerprint similarity. On the basis of the fingerprint similarity, the homogeneity and stability of the tea RMs were tested and similarity values were certified by eight laboratories according to the guidelines for CRMs. The results indicated that each grade of samples had good homogeneity and stability. The fingerprint similarity value and uncertainty at 95% confidence level were certified as 0.918 ± 0.027, 0.662 ± 0.033, and 0.400 ± 0.074 for grades I, II and III, respectively, and the grading was consistent with sensory evaluation. This set of tea CRMs has been certified and issued by the National Technical Committee on Reference Materials as China’s first tea CRM based on the fingerprint classification with quantitative characteristics. This method can be used for grading of Xinyang Maojian tea.

Key words: Xinyang Maojian tea, certified reference material (CRM), grading, flavor components, high performance liquid chromatographic (HPLC) fingerprint, similarity evaluation