Analysis and identification of Chinese drugs by three-step infrared spectroscopy—A case study of Danshen

In this study, two types of Danshen from different growth years were discriminated and identified by a three-step infrared spectroscopy method (Fourier transform-infrared spectroscopy (FT-IR) coupled with second derivative infrared spectroscopy (SD-IR) and two dimensional correlation infrared spectroscopy (2D-IR)). Though only small differences were found in the FT-IR spectra of the samples, the positions and intensities of peaks at around 1635...