Examining the unique retention behavior of volatile carboxylic acids in gas chromatography using zwitterionic liquid stationary phases

Abstract

For the first time, gas chromatographic (GC) stationary phases consisting of zwitterionic liquids (ZILs) possessing sulfonate functional groups were utilized for the analysis of volatile carboxylic acids (VCAs). The highly polar and acidic nature of VCAs significantly limits the number of currently available GC stationary phases, which are all largely based on acid-modified polyethylene glycol. In this study, it is shown that this class of ZILs exhibit strong retention of VCAs with excellent peak symmetry. Unique chromatographic selectivity toward VCAs is also demonstrated by tuning the structural features of the ZILs. The solvation properties of the three ZILs as well as a structurally similar conventional monocationic IL were characterized using the Abraham solvation parameter model.