Beijing Jialin Pharmaceutical Co., Ltd.

A method for the determination of the related substances of atorvastatin calcium was established.An optimal HPLC method was set up.The known impurities were qualified and quantified by standard method.Other impurities were calculated by the main component self-contrasted method.A Wondasil C₁₈ column (4.6 mm×250 mm, 5 μm) was applied.The mobile phase was acetonitrile-tetrahydrofuran-ammonium acetate buffer with a gradient elution at a flow rate of 1.0 mL·min^-1 and the detection wavelength was set at 244 nm.The column temperature was 30°C, and the volume of injection was 20 μL.The resolutions between atorvastatin and adjacent impurities (impurities B and C), and between the known impurities were greater than 1.5.The limits of quantification of impurities A, B, C, D, E were 30, 40, 40, 20, 10 ng.The calibration curves of five known impurities were linear in the self-concentration range (r>0.9901, n=5).The average recovery rates (n=9) were 98.5%, 111.3%, 91.5%, 106.6%, 106.5%; RSDs were 4.8%, 4.1%, 4.7%, 7.3%, 6.4%.The method is reproducible and accurate for determination of the related substances in atorvastatin calcium according to methodol. validation.

Objective: To develop an HPLC method for the determination of enantiomer in ambrisentan.Methods: Reference substance method was used for the qual. and quant. determinationThe separation was performed on a Chiralpak AD-H column (4.6 mm × 250 mm, 5 μm) with the mobile phase of hexane-ethanol (95:5) at a flow rate of 1.0 mL·min^-1, and the detective wavelength was set at 263 nm.Results: Ambrisentan and enantiomer were effectively separated under the above conditions with the resolution higher than 8.0; the calibration curves were linear in the concentration range of 1.04-5.18 μg·mL^-1; the recoveries (n = 3) were 106.6%, 103.4%, and 103.7% resp. at low, medium and high concentrations, with the RSD of 3.0%, 1.4% and 2.2%, resp.; the test solution was basically stable within 24 h.The enantiomer contents in six batches of ambrisentan were 0.15%, 0.13%, 0.09%, not detected, 0.12% and 0.16% resp.Conclusion: The method is suitable for determination of enantiomer in ambrisentan by methodol. validation.