Analysis of chlorobutanol in ophthalmic ointments and aqueous solutions by reverse-phase high-performance liquid chromatography.

A reverse-phase high-performance liquid chromatographic assay for chlorobutanol was developed and found suitable for the routine analysis of ophthalmic ointments and aqueous solutions. The method utilized a column packed with 10-microns octadecylsilane with a mobile phase of methanol-water (50:50). Peak detection was by UV absorption at 210 nm. In this chromatographic system, chlorobutanol had a capacity factor (K') of 4.1. Standard curves obtained in the presence of ointment vehicle containing an aminoglycoside were linear, intercepted at zero, and averaged 99.4% recovery. Degradation studies indicated that the method was stability indicating. The analytical results for a complete experimental ophthalmic ointment and an aqueous ophthalmic diluent are presented. This high-performance liquid chromatographic method of analysis represents an alternative to GC procedures for determining chlorobutanol.