HPLC chromatograms of seven marker compounds detected in different samples under the developed mobile phase system at different detection wavelengths. Letters A, B, C and D denote the four manufacturers. Peaks: (1) Puerarin; (2) Paeoniflorin; (3) Cinnamic acid; (4) Daidzein; (5) Glycyrrhizin; (6) Ephedrine; (7) Pseudoephedrine. A2, B2, C2 and D2 are chromatograms monitored at 230 nm for the quantitative determination of paeoniflorin (peak 2) and also used for the comparison of different samples. A1, B1, C1 and D1 are chromatograms monitored at 207 nm for the determination of ephedrine (peak 6) and pseudoephedrine (peak 7). D3 is a chromatogram monitored at 250 nm for puerarin (peak 1), daidzein (peak 4) and glycyrrhizin (peak 5); and D4 is a chromatogram monitored at 275 nm for cinnamic acid (peak 3).