Separation of Achiral and Chiral Analytes Using Polymeric Surfactants with Ionic Liquids as Modifiers in Micellar Electrokinetic Chromatography

We report the synthesis and characterization of amino acid ester based chiral ionic liquids, derived from L-and D-alanine tert butyl ester chloride. The synthesis was accomplished via an anion metathesis reaction between commercially available L-and D-alanine tert butyl ester chloride using a variety of counterions such as lithium bis (trifluoromethane) sulfonimide, silver nitrate, silver lactate, and silver tetrafluoroborate. Both enantiomeric forms were obtained as confirmed by bands of opposite sign in the circular dichroism spectra. The L-and D-alanine tert butyl ester bis (trifluoromethane) sulfonimide were obtained as liquids at room temperature and intriguingly exhibited the highest thermal stability (up to 263°C). In addition, the ionic liquids demonstrated enantiomeric recognition ability as evidenced by splitting of racemic Mosher's sodium salt signal using a liquid state 19 F nuclear magnetic resonance (NMR) and fluorescence spectroscopy. The L-and D-alanine tert butyl ester chloride resulted in solid salts with nitrate, lactate, and tetrafluoroborate anions. This illustrates the previously observed tunability of ionic liquid synthesis, resulting in ionic liquids of varying properties as a function of varying the anion.

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“…The 1 H NMR (Fig. 1) and 13 C NMR (see Fig. 2) of the ionic liquid was consistent with the chemical structure of AlaC 4 NTf 2 .…”

Section: Synthesis and Characterization Of A New Amino Acid Ester Chisupporting

confidence: 77%

Synthesis and characterization of novel chiral ionic liquids and investigation of their enantiomeric recognition properties

et al. 2007

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“…The abnormality in the tendency of the value of EOF to increase for the lowest IL concentrations added to the BGE is likely due to a slight enhancement in current and the compression of the Helmholtz/mobile layer. A detailed explanation of this phenomenon was presented in our previous study [13]. Of the three ILs presented here, 0.06% v/v EMIMBF 4 provided the best resolution as well as the shortest elution time, as shown in electropherogram II, Fig.…”

Section: Effects Of Ils On the Separation Of Binaphthyl Derivativessupporting

confidence: 63%

“…In addition, the effect of dissolving ILs in the BGE to resolve the overlapping enantiomer peaks of BOH and BNA was investigated [13]. The present work extends our previous study to include enantiomers with a stereogenic carbon which may be challenging to separate, and compares the effect of ILs to MOSs as BGE modifiers.…”

Section: Introductionmentioning

confidence: 65%

“…In addition, the application of ILs can be extended to chiral separations by use of either a chiral IL selector [9 -12] or by dissolving a chiral selector in an achiral IL [13]. Although the separation of enantiomers has become fairly routine, many chiral selectors cannot distinguish closely related chiral molecules, and as a result, there can be considerable enantiomeric peak overlap.…”

Section: Introductionmentioning

confidence: 99%

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

Mwongela

Siminialayi

Fletcher

et al. 2007

J of Separation Science

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A comparison of ionic liquids to molecular organic solvents as additives for chiral separations in micellar electrokinetic chromatographyIn this study, we report the effects of adding ionic liquids (ILs), as compared to adding conventional molecular organic solvents (MOSs), to aqueous buffer solutions containing molecular micelles in the separation of chiral analyte mixtures in micellar EKC (MEKC). The molecular micelle used in this study was polysodium oleyl-L-leucylvalinate (poly-L-SOLV). The ILs were 1-alkyl-3-methylimidazolium tetrafluoroborate, where the alkyl group was ethyl, butyl, hexyl, or octyl. These ILs were chosen due to their hydrophobicity, good solvating, and electrolyte properties. Thus, it was expected that these ILs would have favorable interactions with chiral analytes and not adversely affect the background current. Common CE buffers, mixed with a molecular micelle, and an IL or a MOS, were used for these chiral separations. The buffers containing an IL in the concentration range of 0.02 -0.1 v/v were found to support a reasonable current when an electric field strength of 500 V/cm was applied across the capillary. However, a current break down was observed for the buffers containing more than 60% v/v MOS on application of the above-mentioned electric field. The chiral resolution and selectivity of the analytes were dependent on the concentration and type of IL or MOS used.

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“…Room temperature ionic liquids (RTILs) are ionic compounds that are liquids at ambient temperature and consist of ionic species [21]. RTILs belong to a relatively new class of solvents which are amphiphilic molecules with a hydrophilic polar headgroup (ionic in nature) and a hydrophobic hydrocarbon chain (the tail).…”

Section: Introductionmentioning

confidence: 99%

Analysis of phthalates via HPLC-UV in environmental water samples after concentration by solid-phase extraction using ionic liquid mixed hemimicelles

Cai

Shi

et al. 2008

Talanta

155

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Ionic liquid mixed hemimicelles-based solid-phase extraction for the preconcentration of five phthalates in environmental water sample was investigated in this paper. A comparative study on the use of room temperature ionic liquids (RTILs) 1-hexyl-3-methylimidazolium bromide ([C 6 mim]Br) and 1-dodecyl-3-methylimidazolium bromide ([C 12 mim]Br)-coated silica as sorbents was presented. Owing to having bigger adsorption amounts for analytes [C 12 mim], Br-coated silica was selected as SPE material and the five analytes di-ethyl-phthalate (DEP), di-n-propyl-phthalate (DnPP), di-n-butyl-phthalate (DnBP), di-cyclohexyl-phthalate (DcHP) and di-(2-ethylhexyl)-phthalate (DEHP) can be quantitatively extracted under optimal conditions. The analytes retained on the cartridge were desorbed completely with 3 mL methanol (pH 2). Predominant factors influencing the extraction efficiency, such as RTILs concentration, pH value, ionic strength and breakthrough volume were discussed. The proposed method had been applied to determining the five phthalates in four environmental water samples and concentration factor of 600 was achieved easily. Detection limits obtained ranged between 0.12 and 0.17 g/L. The accuracy of this method was evaluated by recovery measurement on spiked samples, and good recovery results (85-107%) with relative standard deviation (R.S.D.) of below 6% were achieved.

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Separation of Achiral and Chiral Analytes Using Polymeric Surfactants with Ionic Liquids as Modifiers in Micellar Electrokinetic Chromatography

Cited by 130 publications

References 41 publications

Synthesis and characterization of novel chiral ionic liquids and investigation of their enantiomeric recognition properties

Synthesis and characterization of novel chiral ionic liquids and investigation of their enantiomeric recognition properties

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

Analysis of phthalates via HPLC-UV in environmental water samples after concentration by solid-phase extraction using ionic liquid mixed hemimicelles

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