Separation and indirect ultraviolet detection of common fluorine-containing anions by ionic liquids in reversed-phase chromatography

Abstract

A new approach for the simultaneous separation and indirect ultraviolet detection of four common fluorine-containing anions using 1-hexyl-3-methylimidazolium chloride as a mobile phase additive in reversed-phase chromatography was developed. The principle of separation and detection is that fluorine-containing anions and imidazolium cations form ion-pairs with ultraviolet absorption. Under the optimal determining conditions, the limits of detection for tetrafluoroborate, hexafluorophosphate, trifluoroacetate, and trifluoromethane sulfonate were 0.6, 0.6, 1.5, and 3.1?µmol/L, respectively. The approach has been successfully applied to the determination of these anions in ionic liquid samples, and the spiked recovery was between 98.5 and 102.6%. The detection limit, linearity, reproducibility, and accuracy of the approach are suitable for quantitative analysis. The method is simple and easy to popularize because of the use of a common C₁₈ reversed-phase column and ultraviolet detector.