title: Cyclodextrin-modified monolithic columns for resolving dansyl amino acid enantiomers and positional isomers by capillary electrochromatography.
abstract: We describe beta- and gamma-cyclodextrins (beta- and gamma-CD)-modified monolithic columns prepared by sol-gel process and chemical modifications. The monolithic silica column was fabricated inside a fused-silica capillary with 100 microm inner diameter by sol-gel process. The monolithic silica matrix was chemically modified chiral selectors of beta- or gamma-CDs with a spacer of 3-glycidoxypropyltrimethoxysilane by on-column reactions. Gamma-CD-modified monolithic column has successfully been applied for the separation of dansyl amino acid enantiomers. Beta-CD-modified monolithic column has been used for the separation of the positional isomers of o-, m-, and p-cresols and the enantioseparation of racemates of benzoin and several dansyl amino acids by capillary electrochromatography, respectively. For the separation of neutral positional isomers, a positive electric field was applied. However, for the separation of negatively charged analytes, a negative electric field was applied at the inlet of column. The separation efficiency of 5.0 x 10(4) theoretical plates/m for dansyl-L-threonine was obtained at electric field strength of -300 V/cm in the mobile phase of 50 mM 2-(N-morpholino)ethanesulfonic acid (MES)-Tris/methanol (70/30) buffer at pH 7.0. L-enantiomers were eluted as the first peak. Scanning electron micrograph showed that monolithic columns have the morphology of continuous skeleton and large through-pores.
authors.affiliation: Biosensing Research Group, Ubiquitous Interface Laboratory, NTT Microsystem Integration Laboratories, 3-1 Morinosato Wakamiya, Atsugi, Kanagawa 243-0198, Japan. zilinchen2002@yahoo.com
authors.forename: Zilin
authors.initials: Z
authors.lastname: Chen
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ozawa
authors.forename: Katsumi
authors.initials: K
authors.lastname: Uchiyama
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Hobo
mesh_terms: D000596:Amino Acids / Q000302:isolation & purification*; D002021:Buffers; D002845:Chromatography / Q000379:methods; D003505:Cyclodextrins / Q000737:chemistry*; D003619:Dansyl Compounds / Q000302:isolation & purification*; D019075:Electrophoresis, Capillary / Q000379:methods*; D005782:Gels; D006863:Hydrogen-Ion Concentration; D007536:Isomerism; D008855:Microscopy, Electron, Scanning; D012822:Silicon Dioxide; D013237:Stereoisomerism
chemical_list: D000596:Amino Acids; D002021:Buffers; D003505:Cyclodextrins; D003619:Dansyl Compounds; D005782:Gels; D012822:Silicon Dioxide