Development of a liquid chromatographic method for the determination of related substances and assay of d-cycloserine

d-cycloserine or d-4-amino-3-isoxazolidinone is an antibiotic produced by Streptomyces garyphalus and Streptomyces orchidaceus. d-Cycloserine is used in the second line treatment of tuberculosis and is often used in developing countries. Therefore, expensive high-tech techniques are not recommended for analysis. Here, a liquid chromatography method with ultraviolet detection (LC–UV) is described using a base deactivated column (Hypersil BDS column; 25 cm × 4.6 mm I.D.) kept at 45 °C. The gradient method uses mobile phases containing acetonitrile (ACN), 20 mM sodium octane sulphonate (SOS), 0.2 M potassium dihydrogen phosphate buffer pH 2.8, water: A: (4:70:10:16 v/v/v/v) and B: (17:70:10:3 v/v/v/v). The method proved to be robust, linear, repeatable, sensitive, selective and easy to perform. For the related substances test 50 μl of a 0.5 mg/ml d-cycloserine solution is injected. For assay, a concentration of 0.1 mg/ml is proposed to avoid overloading of the detector.