Separation of peptides by HPLC using a surface-confined ionic liquid stationary phase.

A butylimidazolium bromide surface-confined ionic liquid stationary phase was synthesized in-house. The synthesized phase was investigated for the separation of five peptides (Gly-Tyr, Val-Tyr-Val, leucine enkephalin, methionine enkephalin, and angiotensin-II). The peptides were successfully separated in less than 5 min. The effect of trifluoroacetic acid (TFA) on the separation of peptides was evaluated with results confirming that TFA was not acting as ion-pairing agent in separation of peptides on this phase.

Characterization of a novel pyridinium bromide surface confined ionic liquid stationary phase for high-performance liquid chromatography under normal phase conditions via linear solvation energy relationships.

Utilizing linear solvation free energy relationship methodology, a novel pyridinium bromide surface confined ionic liquid (SCIL) stationary phase was characterized under normal phase high-performance liquid chromatographic conditions. A limited set of neutral aromatic probe solutes were utilized to rapidly assess the utility of the LSER model, using mobile phases of hexane modified with 2-propanol. The excellent correlation of the global fit across the mobile phase composition range used in this study for the experimental and calculated retention values (R(2)=0.994) indicates that the LSER model is an appropriate model of characterizing this polar bonded phase under normal phase conditions. For a limited subset of compounds, retention on the pyridinium bromide SCIL stationary phase is more highly correlated with that obtained on a cyano column than on a diol column under NP conditions.