Abstract: Objective: A reverse-phase high performance liquid chromatography (RP-HPLC) coupled with micelle-mediated extraction method was developed for the simultaneous determination of five isoflavonoids such as puerarin, daidzin, daidzein, genistin and genistein from kudzu powder. Methods: The non-ionic surfactant Triton X-114 was used as the extraction solvent. The chromatographic separation of samples was performed on a Phenomenex C18 column using methanol-0.25% glacial acetic acid as the mobile phase by means of gradient elution and a UV detector set at 250 nm was used for detection. The chromatographic conditions were explored to optimize the micelle-mediated extraction and enrichment of cloud points. Results: The highest extraction rate of isoflavonoids was achieved using 3 g/100 mL Triton X-114 as the surfactant for ultrasonic-assisted extraction at 40 ℃ for 30 min with a material/liquid ratio of 1: 100 (g/mL). Sodium chloride was added to the extract to improve extraction rate and cloud point enrichment. The limit of detection (LOD) of this developed method was in the range of 0.016－0.079μg/mL (RSN=3) with average recovery rates ranging between 93.7% and 98.86%. The enrichment factor was approximately 12.5. Conclusion: This developed method is characteristics of simple operation, low cost, high extraction efficiency and less pollution to environment, which is suitable for the quality control of five isoflavonoids in kudzu powder.

Key words: micelle-mediated extraction, cloud point extraction (CPE), Triton X-114 surfactant, isoflavonoids, high performance liquid chromatography (HPLC)