A comparison of ionic liquids to molecular organic solvents as additives for chiral separations in micellar electrokinetic chromatography

Mwongela, Simon M.; Siminialayi, Noreen; Fletcher, Kristin A.; Warner, Isiah M.

doi:10.1002/jssc.200600455

Cited by 30 publications

(21 citation statements)

References 37 publications

(25 reference statements)

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“…The presence of several reagents during the CE separation could complicate the expected interpretations for this limited SEF. Another possible reason is due to the ability of the imidazolium-based cation to adsorb to the walls of the capillary for sufficiently high IL concentrations [67,68].…”

Section: Il-based Surfactants At Nonmicellar Concentrationsmentioning

confidence: 99%

Ionic liquids in enhancing the sensitivity of capillary electrophoresis: Off‐line and on‐line sample preconcentration techniques

2016

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The popularity of ionic liquids (ILs) has grown during the last decade in enhancing the sensitivity of CE through different off-line or on-line sample preconcentration techniques. Water-insoluble ILs were commonly used in IL-based liquid phase microextraction, in all its variants, as off-line sample preconcentration techniques combined with CE. Water-soluble ILs were rarely used in IL-based aqueous two phase system (IL-ATPS) as an off-line sample preconcentration approach combined with CE in spite of IL-ATPS predicted features such as more compatibility with CE sample injection due to its relatively low viscosity and more compatibility with CE running buffers avoid, in some cases, anion exchange precipitation. Therefore, the attentions for the key parameters affecting the performance of IL-ATPSs were generally presented and discussed. On-line CE preconcentration techniques containing IL-based surfactants at nonmicellar or micellar concentrations have become another interesting area to improve CE sensitivity and it is likely to remain a focus of the field in the endeavor because of their numerous to create rapid, simple and sensitive systems. In this article, significant contributions of ILs in enhancing the sensitivity of CE are described, and a specific overview of the relevant examples of their applications is also given.

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Section: Il-based Surfactants At Nonmicellar Concentrationsmentioning

confidence: 99%

Ionic liquids in enhancing the sensitivity of capillary electrophoresis: Off‐line and on‐line sample preconcentration techniques

2016

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“…The ionic liquids 1-dodecyl-3-methylimidazolium bromide [C 12 MIm]Br and 1-tetradecyl-3-methylimidazolium bromide [C 14 MIm]Br were synthesized according to a procedure reported in the literature [32]. Dodecyltrimethylammonium bromide (C 12 TAB, 99%) was purchased from Alfa Aesar.…”

Section: Reagentsmentioning

confidence: 99%

“…However, only a few examples of the analytical utility of long-chain ionic liquids have been reported [12,13,34]. Long-chain ionic liquids were used as additives [12] and were also evaluated as pseudo-stationary phases [13] for micellar electrokinetic chromatography. The ionic liquid 1-hexadecyl-3-methylimidazolium bromide has recently been used as novel extracting system for polycyclic aromatic hydrocarbons contained in sediments using focused microwave-assisted extraction [34].…”

Section: Introductionmentioning

confidence: 99%

“…Recently, the physical and chemical behavior of long-chain alkylimidazolium ionic liquids as new surfactants has been studied [31 -33]. However, only a few examples of the analytical utility of long-chain ionic liquids have been reported [12,13,34]. Long-chain ionic liquids were used as additives [12] and were also evaluated as pseudo-stationary phases [13] for micellar electrokinetic chromatography.…”

Section: Introductionmentioning

confidence: 99%

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Long‐chain alkylimidazolium ionic liquids, a new class of cationic surfactants coated on ODS columns for anion‐exchange chromatography

Qiu

Zhang

Chen

et al. 2008

J of Separation Science

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Separations of common inorganic anions were carried out on ODS columns coated with two long-chain alkylimidazolium ionic liquids ([C(12)MIm]Br and [C(14)MIm]Br) as new cationic surfactants for ion chromatography. With phthalate buffer solution as the mobile phases and non-suppressed conductivity detection, high column efficiencies and excellent selectivity were obtained in the separation of inorganic anions. Chromatographic parameters are calculated and the results show that the coated column possesses significant potential for the analysis of some inorganic anions such as CH(3)COO(-), IO(3)(-), Cl(-), BrO(3)(-), NO(2)(-), Br(-), NO(3)(-), SO(4)(2-), I(-), BF(4)(-), and SCN(-). The effect of eluent pH values on the separation of anions has been studied on the column coated with [C(12)MIm]Br. The stability of the coated columns was also examined.

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“…Solvent-modified micellar EKC is one area of interest in which a modifier is added to improve the separation of analytes. Various groups have studied the impact of using ionic liquids or organic solvents in chiral MEKC in combination with polymeric-based surfactants [4,5]. Chiral EKC without organic modifiers [6] has also been an area of interest and been used for various enantioseparations, including various b-blockers in our group.…”

Section: Introductionmentioning

confidence: 99%

The effect of co‐surfactant‐modified micelles on chiral separations in EKC

2009

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The use of chiral pseudostationary phases in EKC provides high efficiencies and excellent resolution for enantiomeric separations. The chiral pseudostationary phases of interest in this study are alcohol-modified ("swollen") micelles, in which a co-surfactant (medium chain-length alcohol) is added with the surfactant. In this study, the chiral surfactant, dodecoxycarbonylvaline (DDCV), along with the co-surfactant, 2-hexanol, has been prepared as swollen micelle in order to investigate the chiral separation of enantiomeric pairs. Three sets of experiments were investigated in which swollen micelle systems contained: chiral surfactant and racemic co-surfactant; chiral surfactant and chiral co-surfactant; and phase ratio increases, in which both chiral surfactant and chiral co-surfactant were employed. In the first two sets of experiments, co-surfactant concentration was held constant and the surfactant concentration was increased. In the third set of experiments, both surfactant and chiral surfactant concentrations were increased proportionally. The chromatographic figures of merit for each enantiomeric pair were investigated and compared with various chiral aggregate systems. In swollen micelle compositions using constant racemic 2-hexanol concentration, when DDCV concentration increased, enantioselectivity and resolution increased; whereas, efficiency remained constant for most of the test compounds. Compositions using constant S-2-hexanol concentration reached a maximum in all chromatographic figures of merit when DDCV concentration was increased from 2 to 3%. An increase in both surfactant and co-surfactant concentrations led to noisy baselines and chiral aggregates that were generally unstable in solution.

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A comparison of ionic liquids to molecular organic solvents as additives for chiral separations in micellar electrokinetic chromatography

Cited by 30 publications

References 37 publications

Ionic liquids in enhancing the sensitivity of capillary electrophoresis: Off‐line and on‐line sample preconcentration techniques

Ionic liquids in enhancing the sensitivity of capillary electrophoresis: Off‐line and on‐line sample preconcentration techniques

Long‐chain alkylimidazolium ionic liquids, a new class of cationic surfactants coated on ODS columns for anion‐exchange chromatography

The effect of co‐surfactant‐modified micelles on chiral separations in EKC

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