Development and Validation of an HPLC Method for the Simultaneous Analysis of Dextromethorphan HBr, Potassium Guaiacolsulfonate and Sodium Benzoate in Cough Mixture

Abstract

A rapid, sensitive and selective reversed-phase high-performance liquid chromatographic (HPLC) method was developed for simultaneous determination of dextromethorphan hydrobromide (DXM), sodium benzoate (SB) and potassium guaiacolesulfonate (PGS) in cough mixture. The combined drug mixtures were separated
through a Hichrom C8 (octyl), 25 cm x 4.6 mm ID, 5 μm column with a mobile phase composed of methanol and 10 mM phosphate buffer pH 3 (1:1), a flow rate 1ml/min, injection volume 10 μl and quantification by UV detection at λ max 219 nm. The method provided a short analysis time: PGS, tR = 3.07 min; SB, tR = 8.09 min and DXM, tR = 9.29 min. Validation was performed using raw materials and the pharmaceutical preparation which contains the compounds described above. The method was validated for linearity,
precision and accuracy. Five factors were selected to be used in the robustness test (temperature of the column, volume of methanol in the mobile phase, pH of the aqueous phase in the mobile phase, flow rate and time of preparation) and the resolution between SB and DXM was measured for each factor. The statistical treatment (t-test with 4 degrees of freedom and at α = 0.01) did not show significant difference with regard to temperature of the column, pH of the aqueous phase in the mobile phase, flow rate and time of
preparation showing that the method is robustic. With regard to percent organic modifier (methanol) a significant difference was observed indicating that care should be taken during the preparation of mobile phase proportions.

Keywords: high pressure liquid chromatographic method, dextromethorphan HBr, sodium benzoate, potassium
guaiacolsulfonate, cough mixture

Ethiopian Pharmaceutical Journal Vol. 26 (1) 2008: pp. 39-48