Ionic Liquids as Mobile Phase Additives for Feasible Assay of Naphazoline in Pharmaceutical Formulation by HPTLC–UV–Densitometric Method

Abstract

A specific and reliable High-Performance Thin Layer Chromatography (HPTLC) with densitometry detection method has been developed for determination of naphazoline nitrate in nasal drops. The best separation of basic analyte, without spot tailing, was achieved using the mobile phase composed of acetonitrile:water (60:40,v/v) with 1.5 % (v/v) imidazolium-class ionic liquid added and the plates covered with stationary phase based on the RP-18 with F254S (10cm x 20cm). The presented results confirm that imidazolium tetrafluoroborate ionic liquids are efficient suppressors of free silanols, which are considered to be responsible for troublesome and irreproducible chromatographic determinations of basic compounds. The developed chromatographic system was found to be convenient in use and at the same time providing a repeatable assay of naphazoline nitrate in nasal drops, which could not be obtained with the use of standard silanol suppressing mobile phase additives, like triethylamine (TEA) or dimethyloctylamine (DMOA).