Exploration and practice on systematic identification strategy of traditional Chinese medicine prescriptions by high-performance thin-layer chromatography—with Daqinjiao decoction as an example

Chinese medicine formula has been the main dosage form of Traditional Chinese Medicine (TCM) in clinics, which has been widely applied in China, Japan, Korea and other Asian countries or regions for thousands of years. The establishment of scientific, comprehensive and feasible quality control standard of a TCM prescription should be the essential precondition for ensuring its stability and consistent in quality. Thin-layer chromatography (TLC) was one of the qualitative identification methods for TCM prescriptions owing to its features being fast and simple. In this study, a systematic identification strategy with high-performance thin-layer chromatography (HPTLC) for fast identification of multiple herbs in TCM prescriptions is proposed. Consecutive liquid‒liquid extraction with solvents of different polarities (n-hexane, ethyl acetate, water-saturated n-butanol) was applied to divide the water extract into three different fractions. With this strategy, the identification of herbs in the formula would be carried out systematically. The proposed strategy has been successfully applied in the qualitative identification of Daqinjiao decoction, a classic TCM formula consisting of 16 herbs. And 9 of the 16 herbs have been identified in this study by using one sample preparation procedure and three different mobile phases. The established TLC identification method was efficient, accurate, and environment-friendly to a certain extent. Results from this research may provide a possible way for similar studies on other TCM prescriptions.