A NOVEL STABILITY INDICATING HPLC METHOD FOR SIMULTANEOUS ESTIMATION OF GUAIPHENESIN, CHLORPHENERAMINE MALEATE & DEXTROMETHORPHAN HBr

An isocratic HPLC method with UV detection at 225nm is described for simultaneous determination of Guaiphenesin, Chlor-pheneramine Maleate & Dextromethorphan HBr. Chromatographic separation of all three drugs were achieved on Purospher star RP-18e column (Merck) using Mobile phase as 74% Buffer (prepared by dissolving 1.8g dipotassium hydrogen orthophosphate in 1 litre of HPLC grade water, adjusting pH-3 with phosphoric acid) & 26% Acetonitrile. Method offers simplicity, good linearity, symmetric peak shape, and good resolution is achieved in a run time of 13 minutes. The method has been validated for Specificity, Linearity, Accuracy, and Precision. Stress testing which covered Oxidation, acid  and alkali hydrolysis, photolysis and thermal degradation was performed on individual molecules under test to prove the specificity of the method and the degradation products formed were resolved effectively. It has a very good linearity with correlation coefficient value more than 0.999,  % recovery for Guaiphenesin, Chlorpheneramine Maleate &  Dextromethorphan HBr obtained were between 99-101%, and  the relative standard deviation for 5 replicates obtained was less than 0.5%.