Determination of the quaternary ammonium compounds dequalinium and cetylpyridinium chlorides in candy-based lozenges by high-performance liquid chromatography

The retention behaviour of the quaternary ammonium compounds benzalkonium chloride, cetylpyridinium chloride and dequalinium chloride on a 100 X 4.6 mm id cyanopropyl stationary phase column is reported as a function of organic modifier and ionic hydrophobic mobile phase additive concentrations. Optimum liquid chromatographic mobile phases using different mobile phase additives are reported which are suitable for the determination of cetylpyridinium chloride and dequalinium chloride in a variety of candy-based lozenge formulations. The quantitative aspects of assays based on the separation of active ingredients and formulation excipients were established. The generality of application of the assay methods was evaluated by determining the quaternary ammonium content of different lozenges and comparing the values obtained with the stated dose.