Microcolumn ion chromatography of inorganic monovalent cations with indirect photometric detection and a silica gel column

A microcolumn ion chromatography system for the separation of inorganic monovalent cations was developed using effused silica column (50mm length × 0.35 mm i.d.) packed with porous silica gel. The separation was carried out by using benzyltrimethylammonium chloride in aqueous acetonitrile as the mobile phase. Six inorganic monovalent cations such as lithium, sodium, ammonium, potassium, ribidium and cesium were separated within 10 min and indirectly detected at 208 nm. The calibration curves were linear for concentrations up to 0.2 mM for lithium, sodium, ammonium and potassium, while those for other cations were linear up to 0.5 mM. The detection limits of the analytes at S/N = 3 were 3.3–12 μM. The present method was applied to the determination of monovalent cations present in whisky and ketchup samples.