RESUMEN
Abstract Hu-Gu capsule is a traditional Chinese medical formula for preventing glucocorticoid-induced osteoporosis. In this work, an ultra-high performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry was developed for chemical identification of the phytochemical compositions in positive ion mode. A total of 41 compounds were detected in Hu-Gu capsule, and 25 compounds were characterized and identified by retention time, accurate mass within 5 ppm error and characteristic fragment ions. Among of them, four major flavonoids were further quantified by high performance liquid chromatography diode array detection in the four batches. The method was validated in terms of calibration curve regression coefficient (r 2 > 0.9994), repeatability (RSD < 3.5%), intra- and inter-day precision (RSD < 1.1%), recovery (93.0-106.4%), limit of detection (0.1 µg/ml), and limit of quantification (1 µg/ml). The research could provide the analysis of chemical composition and be helpful to control the quality of HGC.