Chiral Selectors in Capillary Electrophoresis: Trends during 2017–2018

Abstract

Chiral separation is an important process in the chemical and pharmaceutical industries. From the analytical chemistry perspective, chiral separation is required for assessing the fit-for-purpose and the safety of chemical products. Capillary electrophoresis, in the electrokinetic chromatography mode is an established analytical technique for chiral separations. A water-soluble chiral selector is typically used. This review therefore examines the use of various chiral selectors in electrokinetic chromatography during 2017–2018. The chiral selectors were both low and high (macromolecules) molecular mass molecules as well as molecular aggregates (supramolecules). There were 58 papers found by search in Scopus, indicating continuous and active activity in this research area. The macromolecules were sugar-, amino acid-, and nucleic acid-based polymers. The supramolecules were bile salt micelles. The low molecular mass selectors were mainly ionic liquids and complexes with a central ion. A majority of the papers were on the use or preparation of sugar-based macromolecules, e.g., native or derivatised cyclodextrins. Studies to explain chiral recognition of macromolecular and supramolecular chiral selectors were mainly done by molecular modelling and nuclear magnetic resonance spectroscopy. Demonstrations were predominantly on drug analysis for the separation of racemates.

Characterization of Amino Acid Based Molecular Micelles with Molecular Modeling

“…Furthermore, since each micelle's counterion was sodium, the first two abbreviations shown in the first column in Table 1, represent sodium (S) and undecyl (U), respectively, while the last two letters refer to the amino acids making up the dipeptide headgroup. The number of repeat units listed in Table 1 is experimentally derived aggregation numbers for molecular micelles formed when 100 mM solutions containing the respective monomeric surfactants were exposed to gamma radiation [20]. When constructing the AABMM systems for MD simulation analysis, surfactant monomer chains were connected with covalent bonds at the end of each monomer's hydrocarbon tail.…”

“…In a 2019 review, Yu, et al discussed several classes of chiral selectors used in CE separations. These included antibiotics like streptomycin, doxycycline, and vancomycin; polysaccharides such as glycosaminoglycans and maltodextrin as well as natural and derivatized cyclodextrins; chiral ionic liquids; oligonucleotides; and molecular micelles [20].…”

Stability study of α‐bromophenylacetic acid: Does it represent an appropriate model analyte for chiral separations?

“…CE is considered as established analytical technique for chiral separations [1,2]. Although many chiral selectors are routinely used, the development of new ones, including chiral ionic liquids (CIL), aptamers, calixarenes, metal–organic frameworks, molecularly imprinted polymers, and others still continues [3–5]. Chiral ionic liquids represent a subclass of ionic liquids that are characterized by the presence of at least one chiral center in their structure.…”

Separation of D,L-Ampicillin by ligand exchange-micellar electrokinetic chromatography

“…The ligand exchange chromatography method was used by Davankov and Rogozhin in 1968 to separate the amino acid isomers [22]. Ligand exchange capillary electrophoresis (LECE), which is accepted as a promising electrophoretic version, is used to analyze a complex mixture of natural compounds [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38]. LECE is mainly used to separate optical isomers of amino and hydroxy acids.…”