Dual-index sequence analytical method for IR fingerprint spectra of ethanolic extract of various gylcyrrhizae's root species components

This article describes a new method for analysis of IR fingerprint spectra (FPS), which characterizes traditional Chinese medicine (TCM). Two new indices of IR FPS are introduced, namely, common peak ratio and variation peak ratio. Their values are calculated by means of the sequent analysis method, in which each sample's IR FPS of the components extracted from Glycyrrhizae root is as a standard, and the sequences are made in accordance with the values of their common peak ratios. This method can distinguish the Glycyrrhizae samples correctly, which belong to different species and are produced in different regions. The dual-index sequent method enables us to identify the Chinese herbs conveniently.