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A high-performance liquid chromatographic method for the determination of liquiritin, glycyrrhizin, hesperidin, cinnamic acid, cinnamaldehyde, honokiol and magnolol in a traditional Chinese medicinal preparation, Wuu-Ji-San, which contains Glycyrrhizae Radix, Citri Leiocarpae Exocarpium, Aurantii Fructus, Cinniamomi Ramulus and Magnoliae Cortex, was established. The samples were separated with a Cosmosil 5C18-AR column by linear gradient elution using 0.03% (v/v) phosphoric acid-acetonitrile (0 min, 95:5; 52 min, 30:70) as the mobile phase at a flow-rate of 1.0 ml/mm and the eluate was detected at 254 nm. n-Propyl benzoate was used as the internal standard and seven regression equations showing linear relationships between the peak-area ratios of each marker to n-propyl benzoate and concentration were obtained. The recoveries of the markers listed above were 84.77, 87.07, 79.81, 72.71, 72.72, 77.15 and 73.74%, respectively. The relative standard deviations were less than 5% (n=5). Very satisfactory and reproducible results were obtained within 52 min for the simultaneous determination of the seven markers. Different processes such as concentration by reduced-pressure evaporation, freeze-drying and spray-drying were studied with regard to their effects on the marker contents. There were only minor effects on most of the markers except cinnamic acid and cinnamaldehyde. Three commercial concentrated products of Wuu-Ji-San were also analysed. The contents of the marker substances in the commercial preparations were different from those in a standard decoction.

A high-performance liquid chromatographic method for the determination of paeoniflorin, ferulic acid and baicalin in the traditional Chinese medicinal preparation Dang-Guei-San, which contains Paeoniae Radix, Swertiae Herba, Cnidii Rhizoma and Scutellariae Radix, was established. The samples were separated with a Cosmosil 5C18-AR column by gradient elution with 0.03% (v/v) phosphoric acid-acetonitrile (0 mm 96:4, 5 mm 84:16, 7 mm 82:18, 14-30 mm 78:22) as the mobile phase at a flow-rate of 1.0 ml/min, with detection at 245 nm. Methylparaben was used as the internal standard and three equations were derived showing linear relationships between the peak-area ratios of marker components (paeoniflorin, ferulic acid and baicalin) to methylparaben and concentration. The recoveries of paeoniflorin, ferulic acid and baicalin were 27.86, 33.89 and 49.31%, respectively. The repeatability (relative standard deviation) was generally less than 5% (n=5). The effects of various processes such as concentration by reduced-pressure evaporation, freeze-drying and spray-drying were studied and commercial concentrated herbal preparations containing Paeoniae Radix, Swertiae Herbs, Cnidii Rhizoma and Scutellariae Radix were also analysed.

HPLC methods for the determination of baicalin in Scutellariae Radix and puerarin in Puerariae Radix were established for the quality control of Chinese medicinal preparations containing these drugs. Ethyl paraben and methyl paraben were used as the internal standards for baicalin and puerarin, respectively. The samples were separated on a Cosmosil 5C 18 column with 0.03% phosphoric acid-acetonitrile (79:21), 0.03% phosphoric acid-acetonitrile (87:13) and 2% acetic acid-methanol (79:21) as mobile phases at flowrates of 1.0 ml/min. Very satisfactory and reproducible results were obtained within 25 min for baicalin and 50 min for puerarin. These methods were also applicable to other prescriptions containing Scutellariae Radix and Puerariae Radix such as Chair-Ger-Jie-Ji-Tang, Dang-Guei-Nian-Tong-Tang and San-Jong-Kuey-Jian-Tang.

A high-performance liquid chromatographic method for the determination of cinnamic acid in Cinnamomi ramulus and paeoniflorin in Paeoniae radix was established. The samples were separated by a LiChrospher RP-18 column with water-acetonitrile-methanolacetic acid (61:34:5:0.1 or 80:15:5:0.1, v/v) as the mobile phase at a flow-rate of 1.0 ml/min. Cinnamic acid and paeoniflorin were determined by UV detection at 280 and 250 nm, respectively. The method was applied to determine the optimum conditions for the extraction of the traditional Chinese medicinal preparation Huang Chi Chien Chung Tong, which contains Cinnamomi ramulus and Paeoniae radix. The results indicate that the best extraction conditions involved the use of an ultrasonic bath at 60 degrees C for 30 min. In this experiment, butyl paraben and methyl paraben were used as the internal standards for cinnamic acid and paeoniflorin, respectively. A good and reproducible separation of cinnamic acid and paeoniflorin was obtained within 15 min. The method was also applicable to other preparations that contain Cinnamomi ramulus and Paeoniae radix such as Guey Chi Chia Long Ku Muu Li Tong, Kuei Chi Chien Chung Tong and Tang Kuei Chien Chung Tong.