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This paper describes a sensitive, specific and rapid high-performance liquid chromatography (HPLC) method for the determination of curcumin in rat plasma. After a simple step of protein precipitation in 96-well format using acetonitrile containing the internal standard (IS), emodin, plasma samples were analyzed by reverse-phase HPLC. Curcumin and the IS emodin were separated on a Diamonsil C(18) analytical column (4.6 x 100 mm, 5 microm) using acetonitrile-5% acetic acid (75:25, v/v) as mobile phase at a flow rate of 1.0 mL/min. The method was sensitive with a lower limit of quantitation of 1 ng/mL, with good linearity (r(2) >or= 0.999) over the linear range 1-500 ng/mL. All the validation data, such as accuracy and precision, were within the required limits. A run time of 3.0 min for each sample made high-throughput bioanalysis possible. The assay method was successfully applied to the study of the pharmacokinetics of curcumin liposome in rats.

A two-dimensional column-switching system without sample loop trapping, where two columns were operated via a six-port switching valve, was employed in the isolation and purification of five isoflavonoids from Rhizoma Belamcandae: tectoridin, iridin, tectorigenin, irigenin and irisflorentin. The introduction of the six-port switching value, instead of a sample loop, assured 100% recovery from the first dimension to the second, and the injection volumes of the second dimension were not restricted. Two configurations were tested in this study. In the first mode, only one column was used in the second dimension and two ‘heart-cutting’ fractions were transported to the same second-dimensional column. In the second mode, two parallel columns were used in the second dimension and two fractions were transported to the two columns. Between the two configurations, the one with two second dimensional columns had double sample size, better resolution and one more purified compound. Both two-dimensional configurations consumed less solvent with even greater efficiency and shorter cycle time compared with conventional gradient methods. All of the isoflavonoids were isolated at high purities of greater than 95% with yields of above 82%. Copyright © 2009 John Wiley & Sons, Ltd.

This study presents an efficient strategy based on microwave-assisted extraction (MAE), HPLC-DAD-MS/MS and high-speed counter-current chromatography (HSCCC) for the rapid extraction, identification, separation and purification of active components from the traditional Chinese medicine Fructus Aurantii Immaturus. An LC-DAD-MS/MS method was applied for the screening and structural identification of main components in crude extract, and five components were preliminarily identified as neoeriocitrin, narirutin, naringin, hesperidin and neohesperidin according to their UV and mass spectra. An efficient MAE method for the extraction of the three most abundant components (narirutin, naringin and neohesperidin) was optimized by the combination of univariate and multivariate approaches. The crude extract was then separated and purified by HSCCC and a total of 61.6 mg of narirutin, 207.3 mg of naringin and 159.5 mg of neohesperidin at high purities of 98.1, 97.2 and 99.5%, respectively, were obtained from 1.42 g of crude extract. The recoveries of these compounds were 86, 93 and 89%, respectively.

A non-aqueous capillary electrophoretic method was established for the determination of berberine in Rhizoma coptidis and its preparations. The effects of organic solvent and the concentrations of sodium acetate were studied, which showed that berberine in extracts of traditional Chinese medicine can be separated successfully in a buffer solution of 75 mmol/L of sodium acetate in methanol containing 1 mol/L of acetic acid. The simple and rapid method was linear in the range 25-200 microgram/mL of berberine and had a good reproducibility, with the relative standard deviation below 2%. Non-aqueous capillary electrophoresis is a satisfactory system for the analysis of alkaloids in traditional Chinese medicine.

A capillary zone electrophoresis method was set up for the separation and determination of glycyrrhizin in Chinese medicinal preparations. Concentrations of Na(2)B(4)O(7) were optimized, which showed that glycyrrhizin in the sample could be separated from interference in the running buffer of 30 mmol/L Na(2)B(4)O(7). Using declofenac as internal standard, the simple method was linear in the range 25-300 microg/mL of glycyrrhizin, and good reproducibility was obtained. The extracts of Radix glycyrrhizae and its preparations could be injected directly for analysis without any pretreatment.