Gas chromatographic retention of alkyl phosphates on ionic liquid stationary phases
Retention behaviors of alkyl phosophates were studied on a series of ionic liquid gas chromatography columns. The selectivity of the IL columns for alkyl phosphates were compared with a 5% phenyl column as a route to evaluating the potential use of IL columns in the analysis of alkyl phosphates in petroleum samples in both one- and multi-dimensional GC. Most interestingly, we demonstrate for the first time the dependence of elution order on separation temperature for members of a homologous series of compounds. At low temperatures it was found that trihexyl phosphate eluted before trioctyl phosphate, while at higher temperatures this pattern was reversed. âº Selectivity of IL columns for alkyl phosphates compared. âº Elution order changes with temperature for homologous series. âº Thermodynamic study shown as tool for column selection.