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

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 (), tetrafluoroborate (), and hexafluorophosphate () organic and inorganic anions of ionic liquids. The analytes were separated using a mobile phase of tetrabutylammonium hydroxidecitric acidacetonitrile 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 CF3COO, , , 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 1.42mg/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 100.1104.4%.