Determination of Degradation Products Occurring in Acidic Solutions of a 21-Aminosteroid (Tirilazad) Using a Gradient Hplc Method

A high performance liquid chromatographic (HPLC) method quantitating degradation products of a 21-aminosteroid (tirilazad mesylate) in acidic solutions is described. Mobile phase elution consists of a 58 minute gradient from 5 to 95% mobile phase A, where mobile phases A and B are (81:9:10:0 v/v) and (5.4:0.6:10:84 v/v) acetonitrile, tetrahydrofuran, 0.2 M ammonium formate/ formic acid buffer (pH 3.5) and water. A base deactivated octadecyl silane column thermostatted at 42°C, and fixed wavelength detection at 254 nm are used for this method. The assay is compatible with thermospray mass spectrometry, offering several advantages for the identification of impurities. Validation of the method, along with the use of mass spectrometry for peak identity and purity is discussed.