Heparin: A Chiral Mobile-Phase Additive for Capillary Zone Electrophoresis

Abstract

Heparin, a naturally occuring, polydisperse, polyanionic glycosaminoglycan, was investigated as a chiral selector for capillary zone electrophoresis. Baseline separations were obtained for a variety of underivatized drugs including antimalarials and antihistamines. Analysis was carried out at a pH of 4.5 or 5 using 2% heparin (w/w) in a 10 mM phosphate buffer under an applied voltage of 15 kV. All of the solutes successfully resolved contained at least two nitrogens with one of the nitrogens incorporated in a heterocyclic aromatic ring. Further, successful enantioresolution seemed to require that the nitrogens be somewhat distant from each other in the molecule. The results suggest that, in addition to electrostatic interactions, solute size may also play a role in the heparin chiral recognition mechanism.

Chiral separations in capillary electrophoresis

“…Heparin was introduced in CE for the separation of antimalarial compounds, antihistamines and of some other compounds (tetramisole, tryptophan methylester, anabazine, nornicotine) [74]. Later, it was used for the separation of the oxaminic enantiomers [75] and, together with dextran sulfate, for the resolution of the chloroquine and chloropheniramine enantiomers [76].…”

Separation of enantiomers by capillary electrophoresis using pentosan polysulfate

“…1A) and there are~30 sulfate groups per molecule. The migration direction of this chiral selector was evaluated using a method described previously [25]. The capillary and the anodic reservoir were filled with run buffer without PPS while the detector reservoir was filled with buffer containing PPS.…”

“…Furthermore, there is a wide range of different linear carbohydrates to choose from, each providing unique characteristics for enantioseparations. Successful examples in this group include chondroitin sulfates [6,19,20], dextrans [6,19,21,22], dextrins [6,23], aminoglycosides [6,24], and heparin [6,19,22,25]. A new linear polysaccharide, pentosan polysulfate, will be examined as a chiral selector in CE.…”

Discontinuous electrokinetic chromatography of parabens using different substituted resonances as pseudostationary phases

“…Since the early separations of uncharged molecules with CE using micellar electrokinetic chromatography (MEKC) introduced by Terabe et al [1], various organic molecular aggregates, such as micelles [2±4] and microemulsions (MEEKC) [5±7] have been studied as chromatographic carriers. Discrete molecules such as oligomerized sodium-10-undecylenate [8], cyclodextrins [9,10], starbust dendrimers [11], ionic polymers [12,13] or chromatographic particles [14] have also been used as pseudostationary phases in CE, offering distinct advantages over micelles, such as higher stability with various electrolyte compositions, specific selectivities, or higher efficiencies. Due to the high diversity of separation problems and analytical requirements, research in the field of EKC and pseudostationary phases is still continuing.…”