KINETIC INVESTIGATION ON THE DEGRADATION OF LORAZEPAM IN ACIDIC AQUEOUS-SOLUTIONS BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

A high performance liquid chromatographic method was developed for the kinetic investigation on the acidic hydrolysis of lorazepam in 0.01, 0.1, and 1.0 M hydrochloric acid solutions. In this study, the simulta neous determination of lorazepam and its main degradation product was performed on a reversed phase BDS C-8 column. The mobile phase consist ed of a mixture of methanol : acetonitrile : buffer solution containin g 0.005 M KH2PO4 and 0.1 M CH3COONH4 adjusted to pH 6.0 with glacial a cetic acid (35 : 20 : 45, v/v/v) pumped at a flow rate of 1.5 mL/min. The UV detector was operated at 230 nm. The main degradation product a ttained under the above mentioned experimental conditions was oro-4-(2 -chlorophenyl)-2-quinazolinecarboxaldehyde which was isolated and iden tified by H-1-, C-13-NMR and mass spectrometry. The proposed method sh owed a relative standard deviation of less than 2.04 % and detection l imits of 0.16 and 0.17 mu g/mL for lorazepam and its main degradation product, respectively.