Nonaqueous capillary electrophoretic behavior of 2-aryl propionic acids in the presence of an achiral ionic liquid

Abstract

Ionic liquids (ILs) appear really attractive as electrolyte additives in nonaqueous capillary electrophoresis (NACE). These salts may offer new possibilities of interactions to modulate analyte effective mobilities. The presence of 1-n-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (BMIM NTf2) in acetonitrile/alcohol background electrolytes (BGEs) was investigated in this work. The aim of this study was to elucidate the influence of the IL concentration on the electrophoretic behavior of four arylpropionic acids and to identify the interactions between the analytes and the IL cation. The influence on mobility of the IL concentration, the nature and the proportion of the organic solvents, and the concentration of the ionic components of the BGE was first studied by a univariate approach. A four-factor D-optimal experimental design was then applied to provide a deeper insight into analyte interaction with IL cation present both free in BGE and adsorbed onto the capillary wall.

Utility of ionic liquids in analytical separations

“…As shown in Fig. 10 26.5 cm/50 lm 3.5 -4.0 min [103] polyphenols are retarded, taking a longer time for elution because they may associate either with the positively charged imidazolium groups coating the capillary wall or with the free imidazolium ions present in the running buffer. Again, the separation was postulated to be due to association (i. e., H-bonding, ion-dipole/ion induced-dipole) interactions between the polyphenols and the imidazolium cations.…”

Determination of organic acids by CE and CEC methods

“…Switching to the use of electrolyte additives in CE separations of organic acids, Francois et al [122] reported the use of achiral ionic liquids to manipulate electrophoretic mobilities of 2-arylpropionic acids. In their study they were able to describe interactions between the solutes and the ionic liquid, 1-n-butyl-3-methylimidazolium bis(trifluoromethane-sulfonyl)imide, in NACE.…”

Enantioseparation of rabeprazole and omeprazole by nonaqueous capillary electrophoresis with an ephedrine‐based ionic liquid as the chiral selector

“…Both the cations coated on the capillary walls and the free cations in the BGEs interacted with the analytes (Francois et al, 2007a). The two analytes (Fig.…”