Chiral Separations Using Heparin and Polyelectrolyte Multilayers in Capillary Electrophoresis

Abstract

& Reports on the use of heparin as a chiral additive show widely different separation conditions and inconsistent results. A systematic evaluation of the separation of pheniramine enantiomers using heparin as a chiral selector suggested that heparin was interacting with the capillary surface at acidic pH. Further testing confirmed the interaction between heparin and the capillary surface at acidic pH causing an increase in the electroosmotic flow (EOF). Polyelectrolyte multilayer (PEM) was chosen as a potential means to eliminate the interaction between heparin and the capillary surface. Generation of the PEMs on a bare capillary was monitored by measuring the changes in EOF following the deposition of each polyelectrolyte layer; deposition provided consistent EOF intensities and facilitated control over EOF direction. Results from this study indicated that a stable PEM system could be generated, which prevents the interaction of heparin with the capillary surface. This PEM system showed excellent reproducibility, with only a slight loss of resolution due to the increased interactions between the analyte and the charged capillary wall.

Polyelectrolyte multilayer coatings for the separation of proteins by capillary electrophoresis: Influence of polyelectrolyte nature and multilayer crosslinking

“…Table 2 displays all the polycation/polyanion couples studied in the present work. Nine polyanions were studied and can be divided into 3 different families: (i) polypeptides/polyamides (polyglutamic acid (Pglu) and poly(L-lysine citramide) (Plc)), (ii) vinylic polymers (poly(styrene sulfonate) (PSS), poly(acrylic acid) (Paa), poly(methacrylic acid) (Pma) and poly(acrylic acidco-acrylamide) at two different aa/am ratios (Paa 80 am 20 and Paa 20 am 80 )) and (iii) polysaccharides (hyaluronic acid (Ha) and dextran sulfate (DS)). Among those polyanions, two carry sulfonate groups and are thus strong polyacids (PSS and DS); the others being weak polyacids based on carboxylate moieties.…”

“…PDADMA/PSS SMIL could be also deposited on poly(methyl methacrylate) microchip [19]. An application of SMIL coatings for chiral separation was investigated using heparin as chiral selector [20]. Mixed mode separation based on MEKC and SMIL was used for the achiral and chiral separation of small molecules [21].…”

Polyelectrolyte Multilayers in Capillary Electrophoresis

“…In the case of a (PDADMAC/PSS) 6 SMIL coating with two different BGE, i. e. 100 mM phosphate (pH 4.2, 5.3 and 6.0) and 100 mM sodium borate at pH 9.5, better separation efficiency was found with 100 mM phosphate buffer BGE at pH 4.2 (111 600 plates/m) than at pH 6 (35 000 plates/m), [26] but EOF was similar (29.6 TU at pH 4.2 and 29.3 TU at pH 6.0). At pH 9.5, EOF mobility remained similar (31.9 TU).…”

Chiral Capillary Electrokinetic Chromatography: Principle and Applications, Detection and Identification, Design of Experiment, and Exploration of Chiral Recognition Using Molecular Modeling

“…Polysaccharides, either the homo-polysaccharides as maltodextrin or the glycosaminoglycan as chondroitin sulfate and heparin, are contributing to about 5% of chiral separation and are much behind CDs in their enantiomeric discrimination power [ 69 , 70 , 71 ]. Sun et al [ 72 ] described a CEKC approach using ethanediamine-bonded poly (glycidyl methacrylate) microspheres as CSs for enantioseparation with chondroitin sulfate E. Better enantioseparation results were obtained using the microsphere for separating basic model chiral compounds compared with using the single system of chondroitin sulfate E.…”