Rapid and simultaneous determination of trifluoroacetate, trifluoromethanesulfonate, tetrafluoroborate, and hexafluorophosphate organic and inorganic anions of ionic liquids by ion-pair chromatography using a reversed-phase silica-based monolithic column and conductivity detection

摘要

An ion-pair chromatographic method was developed on a reversed-phase silica-based monolithic column for the fast and simultaneous determination of trifluoroacetate (CF3COO-), trifluoromethanesulfonate (CF3SO-3), tetrafluoroborate (BF-4), and hexafluorophosphate (PF-6) organic and inorganic anions of ionic liquids. The analytes were separated using a mobile phase of tetrabutylammonium hydroxide-citric acid-acetonitrile on the Chromolith Speed ROD RP-18e column with direct conductivity detection. The effects of eluent, column temperature, and flow rate on the retention of anions were investigated. The experimental phenomenon was discussed according to ion-exchange and hydrophobic interaction mechanism in the separation. The optimized chromatographic conditions were selected. Under the optimal conditions, the baseline separation of CF 3COO-, and was achieved without any interference by other anions (Cl-, Br-, I-, and). The detection limit (S/N = 3) was 3.33, 0.58, 0.27, and 1.42 mg/L for CF3COO -, and, respectively. The method has been successfully applied to the determination of, CF3COO-, and in ionic liquids. The spiked recoveries of the anions were from 100.1-104.4%.