Rapid analysis of astragalus and its extracts by infraredspectroscopy

Abstract

Objective To provide effective reference for quality analysis of the chemical composition and extraction of astragalus separation process by comparing the extract of astragalus and it’s IR spectra. Methods The saponins and flavonoids in astragalus were firstly extracted by the method of circumfluence with ethanol as solvent and the residue of ethanol-extraction was then used to extract polysaccharides by distilled water. Fourier transform infrared spectroscopy (IR) combined with second derivative infrared spectroscopy was applied to quickly identify astragalus herbs powder, water extraction of astragalus, astragalus alcohol extraction and water extraction of the residue of ethanol-extraction. Results The powder and 70% ethanol extract, 80% ethanol extract were around at 1 735 cm-1 (carbonyl stretching vibration absorption peak) has a weak, broad absorption, while the absorption peak was less obvious in boiling water extraction. So the main components of astragalus water extraction are polysaccharides and also contain a small amount of water-insoluble flavonoids. Alcohol extraction mainly contains saponins and flavonoids, and flavonoid extract volume increases with increasing alcohol concentration in a certain range. Conclusion This method can be a quick and easy identification for astragalus and it’s extraction for its chemical composition class, and provide the basis for further research quality. Key words: Astragalus; Water extraction of astragalus; Alcohol extraction of astragalus; IR