Determination of ibuprofen in ointments by reversed-phase liquid chromatography

A selective reversed-phase HPLC method for the determination of ibuprofen in different ointment bases is described. Following a simple dilution step, the drug was separated from interfering compounds on an octadecylsilica column protected by a precolumn. A mobile phase of aqueous tetrahydrofuran buffered by phosphate was used. Detection was monitored at 219 nm. After each 10 injections of lipophilic samples, the columns were washed with tetrahydrofuran and n-hexane. Recoveries of ibuprofen from a new pilot preparation spiked to contain 4, 5, and 6% of the drug were 100.4, 100.3, and 99.7%, respectively. The precision at each concentration was less than 0.8%. The analysis of ibuprofen degeneration products showed that the method also provides an indication of the stability of the drug.