Discrimination of Fritillary according to geographical origin with Fourier transform infrared spectroscopy and two-dimensional correlation IR spectroscopy.

Fritillaria is a traditional Chinese herbal medicine for eliminating phlegm and relieving a cough with a long history in China and some other Asian countries. The objective of this study is to develop a nondestructive and accurate method to discriminate Fritillaria of different geographical origins, which is a troublesome work by existing analytical methods. We conducted a systematic study on five kinds of Fritillaria by Fourier transform infrared spectroscopy, second derivative infrared spectroscopy, and two-dimensional (2D) correlation infrared spectroscopy under thermal perturbation. Because Fritillaria consist of a large amount of starch, the conventional IR spectra of different Fritillaria only have very limited spectral feature differences. Based on these differences, we can separate different Fritillaria to a limited extent, but this method was deemed not very practical. The second derivative IR spectra of Fritillaria could enhance spectrum resolution, amplify the differences between the IR spectra of different Fritillaria, and provide some dissimilarity in their starch content, when compared with the spectrum of pure starch. Finally, we applied thermal perturbation to Fritillaria and analyzed the resulting spectra by the 2D correlation method to distinguish different Fritillaria easily and clearly. The distinction of very similar Fritillaria was possible because the spectral resolution was greatly enhanced by the 2D correlation spectroscopy. In addition, with the dynamic information of molecular structure provided by 2D correlation IR spectra, we studied the differences in the stability of active components of Fritillaria. The differences embodied mainly on the intensity ratio of the auto-peak at 985 cm(-1) and other auto-peaks. The 2D correlation IR spectroscopy (2D IR) of Fritillaria can be a new and powerful method to discriminate Fritillaria.