Objective: To develop a method for quick identification of sun-dried and sulfur-fumigated Cimicifugae Rhizoma by Fourier transform infrared spectroscopy (FTIR).
Methods: The alcoholic and aqueous extracts of sun-dried and sulfur-fumigated Cimicifugae Rhizoma were analyzed and compared by FTIR combined with second derivative infrared spectroscopy.
Results: FTIR spectra showed that there were some differences in the positions of infrared absorption peaks and the relative intensities in the alcoholic and aqueous extracts of sun-dried and sulfur-fumigated Cimicifugae Rhizoma, and the second derivative IR spectra clearly enhanced the spectral resolution of their differences. FTIR spectra showed that the new absorption peaks of Cimicifugae Rhizoma appeared and a part of original absorption peaks disappeared after sulfur-fumigation in aqueous extracts, while a lot of new absorption peaks appeared and the intensities of almost all absorption peaks significantly decreased after sulfur-fumigation in alcoholic extracts. Second derivative IR spectra showed that both sun-dried and sulfur-fumigated Cimicifugae Rhizoma extracted by water differed significantly from each other ranging from about 3 950 to 3 940 cm(-1), 3 850 to 3 800 cm(-1), 1 800 to 1 750 cm(-1), as well as from 1 400 to 1 350 cm(-1); Differences also existed between sun-dried and sulfur-fumigated Cimicifugae Rhizoma extracted by ethanol ranging from about 3 980 to 3 960 cm(-1), 3 850 to 3 800 cm(-1), and 1 500 to 1 460 cm(-1).
Conclusion: The FTIR method combined with the second derivative IR spectrum can be used to analyze and distinguish sun-dried and sulfur-fumigated Cimicifugae Rhizoma quickly and accurately. The developed method provides an efficient approach for the quality control of Chinese herbal medicines with its simplicity and strong specificity.