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A normal-phase enantioselective high-performance liquid chromatographic method was developed for the enantiomeric resolution of naproxcinod, the most advanced cyclooxygenase-inhibiting nitric oxide donator of anti-inflammatory drugs designed for treatment of osteoarthritis. The enantiomers of naproxcinod were resolved on a Chiralpak AD-H (250 × 4.6 mm, 5 μm) column using a mobile phase system containing n-hexane and 2-propanol (95:5, v/v). The resolution between the enantiomers was found to be more than 2.0. The limit of detection and limit of quantitation of (R)-enantiomer were found to be 5 and 15 ng/mL, respectively, for 20 μL injection volume. The sample solution and mobile phase were found to be stable for at least 48 h. The final optimized method was successfully applied to separate (R)-enantiomer from naproxcinod and was proven to be reproducible and accurate for the quantitative determination of (R)-enantiomer in bulk drugs.

A rapid, reliable, and sensitive method for the simultaneous determination of 6 furocoumarins (psoralen, xanthotoxin, bergapten, imperatorin, cnidilin, and isoimperatorin) in Radix glehniae was developed using reversed-phase high-performance liquid chromatography (RP-HPLC) coupled with diode array detection. The HPLC assay was performed on an Ultimate C 18 column (5 μm, 250 mm x 4 mm) with gradient elution of acetonitrile and water within 20 min. The detection wavelength was set at 310 nm. All compounds showed good linearity (r 2 > 0.999). The RSD of intra-day and inter-day variations ranged from 0.2% to 2.7% and 0.3% to 1.7%. The recovery of the assay was in the range of 91.7―107.6%. The method was successfully applied to the simultaneously determination of 6 furocoumarins in Radix glehniae from different areas.

A high-performance liquid chromatography coupled with photo diode array detection method is developed for simultaneous determination of seven active components in Qibaomeiran pill, including rutin, 2,3,5,4'-tetrahydroxystilbene-2-O-beta-D-glycoside, ferulic acid, psoralen, isopsoralen, emodin, and physcion. The analysis is performed on a C(18) column using a mobile phase composed of A (0.1% acetic acid) and B (acetonitrile) with linear gradient elution. Four wavelengths at 245, 290, 320, and 350 nm were chosen as the monitoring wavelength to determine seven active components, respectively. All the compounds show good linearity (r0.999). The developed method is fully validated in respect to precision, repeatability, and accuracy. The proposed method is successfully applied to quantify the seven active components in different Qibaomeiran pill samples. The results indicate that the developed assay could be considered as a suitable quality control method for the Qibaomeiran pill.

A sensitive and specific liquid chromatography-tandem mass spectrometric (LC-MS-MS) method has been developed to determine m-nisoldipine in rat plasma. Sample was pretreated by a single-step protein precipitation with acetonitrile, in contrast to the liquid-liquid procedure frequently used for the extraction of 1,4-dihydropyridines from biologic samples. Separation of analyte and internal standard (I.S.) was performed on a Symmetry RP-C(18) analytic column (50 mm x 4.6 mm, 3.5 microm) with a mobile phase consisting of acetonitrile-water (80:20, v/v) at a flow rate of 0.5 ml/min. The API 4000 triple quadrupole mass spectrometer was operated in multiple reaction monitoring (MRM) scan mode using TurboIonSpray ionization (ESI) source. The method was sensitive with a lower limit of quantification (LLOQ) of 0.2 ng/mL, with good linearity (r>or=0.9982) over the linear range of 0.2-20 ng/mL. All the validation data, such as accuracy, precision, and inter-day repeatability, were within the required limits. The method was successfully applied to pharmacokinetic and relative bioavailability studies of m-nisoldipine polymorphs in rats.

A reversed-phase high-performance liquid chromatography method was established for the simultaneous determination of four major constituents, namely myricitrin, hyperin, quercitroside, and quercetin in Folium Rhododendri Micranthi. The optimal conditions of separation and detection were achieved on a C18 analytical column with a gradient mobile phase consisting of acetonitrile and 1% acetic acid at the flow rate of 1.0 mL/min, and detection wavelength was set at 355 nm. All calibration curves showed good linear regression (r > 0.9993) within test ranges. The reproducibility of relative standard deviations was less than 2.3%, and recovery of analytes was greater than 99.4%, respectively. The method was successfully applied to determine the contents of four compounds in Folium Rhododendri Micranthi. The results indicated that the contents of myricitrin, hyperin, quercitroside and quercetin in Folium Rhododendri Micranthi were 0.166%, 0.303%, 0.299%, and 0.053%, respectively.