A new easy-to-prepare homogeneous continuous electrochromatographic bed for enantiomer recognition

Ákos Végvári, András Földesi, Csaba Hetényi, Olga Kocnegarova, Martin G. Schmid, Vilma Kudirkaite, Stellan Hjertén

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Abstract

Completely homogeneous polyacrylamide-based gels were used for capillary electrochromatography (CEC) of drug enantiomers. Like continuous beds (also called continuous polymer rods, silica rods, monoliths) they do not require frits to support the bed because it is covalently linked to the capillary wall. A long lifetime is an important feature of the beds. The gel matrices can be prepared in any laboratory and for specific interactions they can be derivatized with appropriate ligands. The application range is, therefore, broad. For chiral electrochromatography, negatively and positively charged polyacrylamide gels copolymerized with 2-hydroxy-3-allyloxy-propyl-β-cyclodextrin (allyl-β-CD) were prepared. The latter monomer was synthesized from β-CD and allyl-glycidyl ether by a very simple one-step procedure. Eight acidic, neutral and basic drug compounds were resolved into their enantiomers, most of them with baseline separation. Interestingly, the resolution is independent of the electroendosmotic velocity, i.e., rapid analyses will not give low resolution. Upon increasing this velocity, the plate height for the fast enantiomer did not change (or decreased slightly), whereas that for the slow enantiomer increased. Only the last term in the van Deemter equation contributed significantly to the total plate height. The composition of the gel was chosen such that the 'pores' became large enough to guarantee a satisfactory electroendosmotic flow (EOF). This open gel structure explains why acetone diffused as in free solution, i.e., independently of the presence of the gel matrix. This finding also indicates that the separation of small molecules in polyacrylamide gels cannot be explained by 'molecular-sieving', but rather by some type of adsorption ('aromatic adsorption'?).

Original languageEnglish
Pages (from-to)3116-3125
Number of pages10
JournalELECTROPHORESIS
Volume21
Issue number15
DOIs
Publication statusPublished - Oct 9 2000

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Keywords

  • Allylated-β-cyclodextrin
  • Continuous beds
  • Electrochromatography
  • Enantiomer separation
  • Homogeneous gels
  • Van Deemter equation

ASJC Scopus subject areas

  • Analytical Chemistry
  • Biochemistry
  • Clinical Biochemistry

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