[Fluorescence spectra of Bletilla striata aqueous extraction].

Three-dimensional fluorescence spectrum and ultraviolet absorption spectrum of Bletilla striata extraction drawn by boiling water were reported. Three fluorescence peaks, located at lambda(ex)/lambda(em) = 227/299 nm, 271/299 nm and 258/ 389 nm respectively, were observed in the three-dimensional fluorescence spectrum. Among them, the two former peaks having the same emission wavelengths were produced by one fluorescent component, while the latter peak was produced by another. Three-dimensional fluorescence spectrum is a characteristic mark of Bletilla striata, therefore it can be used in qualitative identification. The distance between emission wavelengths of the two components was 90 nm, so the fluorescence intensity of two components could be measured separately without pre-separation. For dilute solutions of Bletilla striata aqueous extraction, good linear relationships between fluorescence intensity and concentration of two components were obtained, thereby the quantitative determination of the two components may be carried out. In the range of pH 1.5 to pH 12.5, the fluorescence intensity of the two components changes with the increase in pH, indicating dissociable protons exist in the molecular structure of the two components.

[Fluorescence spectra of Dichroa febrifuga aqueous extraction].

Fluorescence spectra of chang shan (Dichroa febrifuga Lour) aqueous extraction were studied. In the three-dimensional fluorescence contour spectrum, three fluorescence peaks of quinazoline alkaloids, which are the active components of chang shan, were observed. The excitation wavelengths of the peaks were 235, 270 and 320 nm, respectively, and the emission wavelength of all the peaks was 430 nm. Three-dimensional fluorescence contour spectrum is the very image of fingerprint, suitable for qualitative identification of traditional Chinese medicine. In the range of pH 3 to pH 6, the fluorescence spectrum of chang shan aqueous extractions changes with the variation in pH value. The reason for this spectral change might be the protonation of N-1 in quinazolone ring of beta-dichroine (febrifugine) molecule. There is an excellent linear relationship between the fluorescence intensity and the concentration of chang shan under nearly neutral conditions, thereby a quantitative method for the determination of quinazoline alkaloids may be established.