A stability-indicating liquid chromatographic method for Lomustine

A simple, inexpensive and rapid liquid chromatography (LC) method has been developed for the quantitative determination of Lomustine, an chemotherapy drug. Degradation studies were performed on the bulk drug by heating to 60 °C, exposure to UV light at an energy of 200 Wh/m2and to visible light at an illumination of not less than 1.2 million lux hours, acid (0.1N hydrochloric acid), base (0.1N sodium hydroxide) aqueous hydrolysis and oxidation with 6.0% (v/v) hydrogen peroxide. Good resolution between the peaks corresponding to impurities produced during synthesis, degradation products and the analyte was achieved on a Symmetry C 8 LC column using a mobile phase consisting of a mixture of aqueous potassium dihydrogen phosphate and acetonitrile. The degradation samples were assayed against the reference standard of Lomustine and the mass balance in each case was close to 99.9%. Validation of the method was carried out as per International Conference on Harmonization (ICH) requirements.