HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC DETERMINATION OF BENZALKONIUMAND NAPHAZOLINE OR TETRAHYDROZOLINE IN NASAL AND OPHTHALMIC SOLUTIONS

A high-performance liquid chromatographic method is described for the determination of benzalkonium chloride homologues and naphazoline nitr ate or tetrahydrozoline hydrochloride in ophthalmic and nasal solution s. The technique involves a one-step dilution (1:5) for sample prepara tion and direct injection onto a 5 mm RP C-8 column. The mobile phase is acetonitrile-diluted acetic acid (80:20, v/v) with 6 mM tetramethyl ammonium bromide. Detection is carried out at 260 nm with a diode arra y. The method is rapid, specific, reproducible and is especially usefu l for quality control procedures.