Separation of inorganic anions on a chemically bonded 18-crown-6 ether stationary phase in capillary ion chromatography.

Inorganic anions were separated on a chemically bonded 18-crown-6 ether (18C6E) stationary phase in capillary ion chromatography. In this study 18C6E groups were chemically bonded on silica gel via reaction with 3-glycidyloxypropyltrimethoxysilane, followed by reaction with 2-aminomethyl-18C6E. Analyte anions were separated in the ion-exchange mode based on the fact that the eluent cation was trapped on the 18C6E and it worked as the anion-exchange site. The eluent cation and eluent anion as well as the eluent concentration affected the retention of the analyte anions. Different selectivity was achieved by using an acetonitrile-rich eluent. The present stationary phase was applied for the determination of UV-absorbing anions contained in saliva samples.