Rapid determination of total benzalkonium chloride content in ophthalmic formulation

A simple and rapid reversed-phase HPLC method was developed for routine analysis of total benzalkonium chloride in ophthalmic formulations. The analysis involves simple sample preparation using the mobile phase as the diluent. The method uses a Waters SymmetryShield RP-18 (75 mm x 4.6 mm, 3.5 microm particle size) column and a mobile phase consisting of a mixture of methanol-potassium phosphate (pH 3.0; 7.5 mM) (68:32, v/v). Using these conditions, three major homologs of the benzalkonium chloride (C(12), C(14) and C(16)) were separated in less then 7 min. Furthermore, recoveries ranging from 97% to 99% at three levels of the label claim of total benzalkonium chloride content were obtained for different ophthalmic formulations. Data supporting the development and validation of this method are presented.