Extractive Spectrophotometric Methods for the Determination of Metaprolol Succinate in Pure and Pharmaceutical Formulations

Two simple, rapid and sensitive extractive spectrophotometric methods have been developed for the assay of metaprolol succinate (MPS) in pure and pharmaceutical formulations. These methods were based on the formation of chloroform soluble ion-association complexes of MPS with bromocresol green (BCG) in NaOAc-HCl buffer of pH 3.29 [Method A] and with bromophenol blue (BPB) in KCl-HCl buffer of pH 2.2 [Method B]. The coloured products have absorption maxima at 415 nm and 412 nm for method A and method B, respectively. The coloured products obeyed Beer's law in the concentration ranges of 0.2-8.2 and 0.1-6.5 μgml-1 for methods A and B, respectively. The molar absorptivity values as obtained from Beer's data were found to be 5.6x104 and 7.01x104 l.mol-1cm-1 while Sandell's sensitivity values were calculated to be 11.64 and 9.30 ng cm-2 for method A and method B, respectively. No interference was observed from common excipients present in pharmaceutical formulations. The methods were successfully applied for the analysis of pharmaceutical formulations.