title: On-line sample preconcentration by sweeping and poly(ethylene oxide)-mediated stacking for simultaneous analysis of nine pairs of amino acid enantiomers in capillary electrophoresis.
abstract: This study proposes a sensitive method for the simultaneous separation and concentration of 9 pairs of amino acid enantiomers by combining poly(ethylene oxide) (PEO)-based stacking, β-cyclodextrin (β-CD)-mediated micellar electrokinetic chromatography (MEKC), and 9-fluoroenylmethyl chloroformate (FMOC) derivatization. The 9 pairs of FMOC-derivatized amino acid enantiomers were baseline separated using a discontinuous system, and the buffer vials contained a solution of 150 mM Tris-borate (TB), 12.5% (v/v) isopropanol (IPA), 0.5% (w/v) PEO, 35 mM sodium taurodeoxycholate (STDC), and 35 mM β-CD, and the capillary was filled with a solution of 1.5 M TB, 12.5% (v/v) IPA, 35 mM STDC, and 35 mM β-CD. Based on the difference in viscosity between the sample zone and PEO solution and because of the STDC sweeping, the discontinuous system effectively stacked 670 nL of the 9 pairs of FMOC-derivatized amino acid enantiomers without losing chiral resolution. Consequently, the limits of detection for the 9 pairs of FMOC-derivatized amino acid enantiomers were reduced to 40-60 nM. This method was successfully used to determine d-Tryptophan (Trp), l-Trp, d-Phenylalanine (Phe), l-Phe, d-Glutamic acid (Glu), and l-Glu in various types of beers.
authors: Department of Chemistry, National Kaohsiung Normal University, Taiwan.
authors: En-Ping
authors: EP
authors: Lin
authors: Kai-Cheng
authors: KC
authors: Lin
authors: Chia-Wei
authors: CW
authors: Chang
authors: Ming-Mu
authors: MM
authors: Hsieh
mesh_terms: D000596:Amino Acids / Q000032:analysis* / Q000737:chemistry; D020374:Chromatography, Micellar Electrokinetic Capillary; D005449:Fluorenes / Q000737:chemistry; D009281:Naphthalenes / Q000737:chemistry; D009862:Online Systems; D011092:Polyethylene Glycols / Q000737:chemistry*; D013237:Stereoisomerism; D013657:Taurodeoxycholic Acid / Q000737:chemistry; D047392:beta-Cyclodextrins / Q000737:chemistry; D009764:o-Phthalaldehyde / Q000737:chemistry
chemical_list: D000596:Amino Acids; D005449:Fluorenes; D009281:Naphthalenes; D047392:beta-Cyclodextrins; D011092:Polyethylene Glycols; D013657:Taurodeoxycholic Acid; D009764:o-Phthalaldehyde; C027717:2,3-naphthalenedicarboxaldehyde; C054007:1-(9-fluorenyl)methyl chloroformate; C031215:betadex
keywords: 9-fluorenylmethylchlorofrormate; Amino acid; Capillary electrophoresis; Chiral separation; Polyethylene oxide; Stacking