Application of terahertz technology in the identification of traditional Chinese medicine

In recent years, terahertz time-domain spectroscopy(THz-TDS), as a new spectral analysis method, has become a hot research. Terahertz time-domain spectroscopy can acquire spectral data with high SNR over a board range of THz frequencies. Terahertz technology has been widely used in the quality control of traditional Chinese medicine. In this paper, Terahertz time-domain spectroscopy combined with chemometrics was used to analyze the differences between two kinds of medicines-Bailing capsules and Jinshuibao capsules. The time-domain signal of the samples can be obtained by THz-TDS. And the refractive index and absorption coefficient of samples can be calculated. The PCA scores of 2Dplots (PC1xPC2) of Bailing and Jinshuibao capsules were obtained through principal component analysis(PCA), and the cumulative contribution rate of the first two principal components exceeds 98%. Their absorption coefficients were used as the characteristic data of cluster analysis. Euclidean distance was used to cluster and identify the samples. The results shows that twenty different batches of TCM were divided into two categories, with a slight crossover in the middle. The clustering precision of Jinshuibao capsules is 100%, while the clustering precision of Bailing capsules is 81. 8%. The results show that the clustering method can effectively analyze the terahertz time-domain spectrum of traditional Chinese medicine.