Recent innovations in the use of charged cyclodextrins in capillary electrophoresis for chiral separations in pharmaceutical analysis

Abstract

A review is presented on the use of charged cyclodextrins (CDs) as chiral selectors in capillary electrophoresis (CE) for the separation of analytes in pharmaceutical analysis. An overview is given of theoretical models that have been developed for a better prediction of the enantiomeric resolution and for a better understanding of the separation mechanism. Several types of charged CDs have been used in chiral capillary electrophoretic separation (anionic, cationic, and amphoteric CDs). Especially the anionic CDs seem to be valuable due to the fact that many pharmaceutically interesting compounds can easily be protonated (e.g., amine groups). For that reason several anionic CDs are now commercially available. Cationic and amphoteric CDs are less common in chiral analysis and only a few are commercially available. Attention is paid to the most common synthesis routes and the characterization of the CDs used in chiral capillary electrophoretic separations. The degree of substitution in the synthesized CDs may vary from one manufacturer to another or even from batch to batch, which may have a detrimental effect on the reproducibility and ruggedness of the separation system. In Sections 4, 5, and 6 the applications of anionic, cationic, and amphoteric CDs for the chiral separation in CE are described. Many interesting examples are shown and the influence of important parameters on the enantioselectivity is discussed.

Exploring versatile applications of cyclodextrins: an overview

“…Besides all the above advantages, CD also aids in microscaling of already used separation technologies; for instance, different capillary techniques including capillary electrophoresis, microbore liquid chromatography and microdialysis. CDs are also employed in bulk scale preparations mainly extractions, dialysis, foam floatation, membrane separation and electrophoresis (De Boer et al, 2000). Table 12 lists few examples of the role of CDs in separation process of various drugs.…”

Enantioselective analysis of omeprazole in pharmaceutical formulations by chiral high-performance liquid chromatography and capillary electrophoresis

“…One of the most successful charged CD is sulfated β-CD, whose mobility is opposite to the electroosmotic flow showing high strong resolving power even at very low concentrations. 25 Sulfated β-CD has been successfully used by our group for the enantiomeric separation of a series of pharmaceutical compounds. [26][27][28][29] 321…”

Análise enantiosseletiva de fármacos: contribuições da cromatografia líquida de alta eficiência e eletroforese capilar

“…Entre os derivados carregados de CDs disponíveis comercialmente, destacam-se a β-CD carboxilada, a β-CD sulfobutiléter e a β-CD sulfatada. Essas CDs estão sendo cada vez mais citadas na literatura, em um grande número de separações quirais para compostos de diferentes classes 81,[84][85][86][87][88][89][90][91][92][93][94][95] . A separação de enantiômeros empregando os derivados de CDs depende não apenas do tipo de CD e de sua concentração, mas também de outras características como grau de substituição e posição em que os substituintes se encontram.…”

“…A separação de enantiômeros empregando os derivados de CDs depende não apenas do tipo de CD e de sua concentração, mas também de outras características como grau de substituição e posição em que os substituintes se encontram. No caso particular da β-CD sulfatada, as separações podem ser obtidas empregando derivados aleatoriamente substituídos com grau de substituição (DS) de 7-11 ou derivados altamente substituídos (DS = 12), nos quais os grupos hidroxilas do carbono 6 estão completamente sulfatados, os grupos da posição 2, parcialmente sulfatados (70%) e os da posição 3 encontram-se não substituídos 84 . A separação de enantiômeros empregando CDs também pode ser feita no modo MEKC através da combinação de tensoativos aquirais com carga, como o dodecilsulfato de sódio, e CDs neutras.…”