Optimisation of ultrasound extraction for flavonoids from semen astragali complanati and its identification by HPLC‐DAD‐MS/MS

The optimisation of ultrasound extraction of semen astragali complanati flavonoids was studied by measuring characteristic absorbance at 266 nm as the response and using response surface methodology (four‐variable, three‐level Box–Behnken design, BBD) in this article. The optimal conditions were obtained as 52 °C, 34 min, 26:1 (mL:g) and 100 mesh (0.120–0.150 mm) for extraction temperature, extraction time, solvent‐to‐sample ratio as well as particle size, respectively. Under these conditions, validation experiments were carried out and the experimental value of A₂₆₆ was 0.9907 ± 0.032 (n = 3), which corresponded to an experimental extraction yield of 7.08%. Compounds in the extracts obtained with the optimum extraction conditions were identified by high‐performance liquid chromatography coupled with diode array and mass spectrometry detectors (HPLC–DAD–MS). Among the 14 compounds that were tentatively identified in the extracts according to their ultraviolet‐visible spectroscopy, mass spectrometry and related literature reports, four were reported for the first time.