Extraction-Spectrophotometric Determination of Trace Amounts of Lorazepam in Pharmaceutical Formulation

摘要

A simple and sensitive extraction-spectrophotometric method for the determination of lorazepam(LOR)in pharmaceutical formulations is reported.The LORH~+ cation which is formed in an acidic solution can form an ion-pair with Orange(II)anionic dye the LORH~+-OR(II)~-ion pair is quantitatively extracted into dichloromethane solvent and its absorption was measured at 482 nm.The calibration graph is linear over the LOR concentration range of 1.0-25.0 ug mL~(-1)and the regression coefficient is 0.9999.The relative standard deviation(RSD)of 10 replicate determination of lO.Oug mL~(-1)of LOR is 1.6 % and the limit of detection(LOD)of the method is 4.8 x 10"2 ug mL~(-1).The method is successfully applied to the determination of LOR amount in pharmaceutical formations(1.0 and 2.0 mg tablets).