title: On the use of ionic liquids as mobile phase additives in high-performance liquid chromatography. A review.
abstract: The popularity of ionic liquids (ILs) has grown during the last decades in several analytical separation techniques. Consequently, the number of reports devoted to the applications of ILs is still increasing. This review is focused on the use of ILs (mainly imidazolium-based associated to chloride and tetrafluoroborate) as mobile phase additives in high-performance liquid chromatography (HPLC). In this approach, ILs just function as salts, but keep several kinds of intermolecular interactions, which are useful for chromatographic separations. Both cation and anion can be adsorbed on the stationary phase, creating a bilayer. This gives rise to hydrophobic, electrostatic and other specific interactions with the stationary phase and solutes, which modify the retention behaviour and peak shape. This review updates the advances in this field, with emphasis on topics not always deeply considered in the literature, such as the mechanisms of retention, the estimation of the suppressing potency of silanols, modelling and optimisation of the chromatographic performance, and the comparison with other additives traditionally used to avoid the silanol problem.
authors.affiliation: Departament de Química Analítica, Universitat de València, c/Dr. Moliner 50, Burjassot, Spain. Electronic address: celia.garcia@uv.es.
authors.forename: M C
authors.initials: MC
authors.lastname: García-Alvarez-Coque
authors.affiliation: Departament de Química Analítica, Universitat de València, c/Dr. Moliner 50, Burjassot, Spain.
authors.forename: M J
authors.initials: MJ
authors.lastname: Ruiz-Angel
authors.affiliation: Institut des Sciences Analytiques, Université de Lyon, CNRS, 69100 Villeurbanne, France.
authors.forename: A
authors.initials: A
authors.lastname: Berthod
authors.affiliation: Departament de Química Física i Analítica, Universitat Jaume I, Cra. Borriol s/n, Castelló, Spain.
authors.forename: S
authors.initials: S
authors.lastname: Carda-Broch
keywords: Additives; High-performance liquid chromatography; Ionic liquids; Mechanisms of retention; Optimisation; Silanol suppression