Ionic Liquid-Based Surfactants in Separation Science

Abstract

A group of nearly forty-eight (48) of surfactants based on ionic liquids (ILs) has been described. The physicochemical and interfacial behavior for several of these IL-based surfactants has been reported since 2004. This review attempts to summarize the important applications that IL-based surfactants have had in analytical chemistry and separation science. Thus, they have been successfully used as extractant systems as substitutes to conventional organic solvents in extraction schemes, or by modifying the chemical structure of conventional extractant sorbents. The analytical performance of these novel IL-based surfactants has been shown to be better than conventional solvents and even better than conventional cationic surfactants. IL-based surfactants have also been used as mobile phase and stationary phase modifiers in high-performance liquid chromatography (HPLC), as modifiers of the electrokinetic chromatographic (EKC) medium, or as the micellar component in capillary electrophoresis (CE). Thus, IL-based surfactant methods constitute a promising and developing area within separation science.

Keywords:

• capillary electrophoresis
• high performance liquid chromatography
• ionic liquids
• ionic liquid surfactants
• surfactants

ACKNOWLEDGEMENTS

V.P. thanks the Spanish Ministry of Science and Innovation (MICINN) for the Ramón y Cajal contract with the University of La Laguna (ULL). M.G.H. thanks the ULL for her PhD fellowship (SEGAI grant). A.M.P. thanks the Environmental Service of the ULL (SEMALL) for financial support. J.L.A. thanks the Analytical and Surface Chemistry Program in the Division of Chemistry and the Separation and Purification Processes Program in the Chemical, Environmental, Bioengineering, and Transport Systems Division from the National Science Foundation for a CAREER grant (CHE-0748612).

Notes

^a RR: Relative recovery.

^b RSD: relative standard deviation.

^c LODs: Limits of detection.

^d Bioactive component.

^e MAE: microwave-assisted extraction.

^f UAE: ultrasound-assisted extraction.

^g PAHs: polycyclic aromatic hydrocarbons.

^h Calculated as LOD of analyte in the sample solution × dilution factor (the ratio volume of sample solution to weight of solid sample dissolved in it).