title: Molecularly bonded chitosan prepared as chiral stationary phases in open-tubular capillary electrochromatography: comparison with chitosan nanoparticles bonded to the polyacrylamide phase.
abstract: The chiral selector, chitosan (CS), was attached to the silanized capillary via a silane coupling agent, (3-glycidyloxypropyl)trimethoxysilane (GTS), to form the GTS-CS capillary, and results for this capillary were compared with those of a previous study on the copolymerization of CS with methacrylamide (MAA) (forming the MAA-CS capillary). The GTS-CS capillary did not exhibit enantioselectivity for d/l-tryptophan, whereas the GTS-BSA capillary, which was prepared by replacement of CS with bovine serum albumin (BSA), succeeded in the chiral separation with an Rs=2.4 in Tris buffer (50mM, pH 8.5). To increase CS attachment, the CS units were crosslinked by succinic acid, and the resulting GTS-CS-s capillary phase improved the resolution to 1.9. Alternatively, the SiH-CS-s capillary was constructed by CS attachment on the silicon hydride phase via stepwise silanization and hydrosilation reactions and crosslinking by succinic acid, but this approach could only achieve a resolution of 1.4 in Tris buffer (50mM, pH 9.5). Although the GTS-CS-s and SiH-CS-s capillaries were still inferior to the MAA-CS capillary (Rs=3.8), the enantioselectivities of the three capillaries were all in the range of 1.4-1.6. For the (±)-catechin sample, the plate heights of the GTS-CS-s and SiH-CS-s capillaries conditioned in pH 8.5 Tris buffer with 60% MeOH modifier were 0.9 cm ((-)-catechin) and 6.0 cm ((+)-catechin)) and 2.9 cm (-) and 3.2 cm (+), respectively, and these heights were comparable to the MAA-CS capillary (2.5 cm (-), 6.0 cm (+)) in pH 6.6 phosphate buffer with 80% MeOH. Finally, a racemate of ibuprofen, a weakly acidic anti-inflammatory drug, was successfully baseline resolved by the GTS-CS-s and SiH-CS-s capillaries in the borate buffers, which were 30 mM at pH 7.5 and 10mM at pH 8.0, respectively.
authors.affiliation: School of Pharmacy, China Medical University, No. 91 Hsueh-Shih Road, Taichung 40402, Taiwan. cjl@mail.cmu.edu.tw
authors.forename: Jian-Lian
authors.initials: JL
authors.lastname: Chen
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry*; D002392:Catechin / Q000737:chemistry; D048271:Chitosan / Q000737:chemistry*; D020374:Chromatography, Micellar Electrokinetic Capillary / Q000379:methods*; D053758:Nanoparticles; D013237:Stereoisomerism; D014364:Tryptophan / Q000737:chemistry; D000099166:Polyacrylamides
chemical_list: D000180:Acrylic Resins; D002392:Catechin; D048271:Chitosan; D014364:Tryptophan; D000099166:Polyacrylamides