Analytical Sciences

Simplex-optimized Chromatographic Resolution of Selected Ionic Liquid Cations Utilizing a Polar Reversed-Phase System

Joanna NICHTHAUSER,* Monika PASZKIEWICZ,* Andrzej C. SKLADANOWSKI,** and Piotr STEPNOWSKI*

*Department of Environmental Analysis, Faculty of Chemistry, University of Gdansk, Sobieskiego 18, PL-80-952 Gdansk, Poland
**Department of Molecular Enzymology, Intercollegiate Faculty of Biotechnology, Medical University of Gdansk, ul. Debinki 1, 80-211 Gdansk, Poland

This study reports on optimization of the RP-HPLC separation of imidazolium and pyridinium ionic liquid cations using a variable-size simplex algorithm. Under the optimized conditions, all critical pairs of ionic liquids were successfully separated in a single chromatographic run. The mobile phase at the point corresponding to the optimum consisted of 10% MeOH and 90% 15 mM KH₂PO₄/H₃PO₄ with pH 3.43. The coefficients of asymmetry for all of the compounds analyzed at the simplex algorithm optimum ranged from 0.83 to 2.91.

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