title: A microchip electrophoresis-mass spectrometric platform for fast separation and identification of enantiomers employing the partial filling technique.
abstract: A microchip electrophoresis-mass spectrometric (MCE-MS) method was developed for fast chiral analysis. The proposed MCE-MS platform deployed a glass/PDMS hybrid microchip with an easy-to-fabricate monolithic nanoelectrospray emitter. Enantiomeric MCE separation was achieved by means of the partial filling technique. A novel chip design with an arm channel connecting to the middle of the MCE separation channel for delivering the chiral selector was tested and proven valid. Enantiomeric separation of3.4-dihydroxyphenylalanine (DOPA), glutamic acid (Glu), and serine (Ser), the selected test compounds,were achieved within 130 s with resolution values (R(s)) of 2.4, 1.1, and 1.0, respectively. The proposed chiral MCE-MS assay was sensitive and had detection limits of 43 nM for l-DOPA and 47 nM for d-DOPA.The analytical platform was well suited for studies of stereochemical preference in living cells because it integrated cell culture, sample injection, chiral separation, and MS detection into a single platform.Metabolism of DOPA in human SH-SY5Y neuronal cells was studied as a model system. On-chip incubation of SH-SY5Y cells with racemic DOPA was carried out, and the incubation solution was injected and in-line assayed at time intervals. It was found that l-DOPA concentration decreased gradually as incubation time increased while the concentration of coexisting d-DOPA remained constant. The results firmly indicated that SH-SY5Y cells metabolized l-DOPA effectively while left d-DOPA intact.
authors.forename: Xiangtang
authors.initials: X
authors.lastname: Li
authors.forename: Dan
authors.initials: D
authors.lastname: Xiao
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Ou
authors.forename: Cassandra
authors.initials: C
authors.lastname: McCullm
authors.forename: Yi-Ming
authors.initials: YM
authors.lastname: Liu
mesh_terms: D002460:Cell Line; D002477:Cells / Q000737:chemistry / Q000378:metabolism; D004295:Dihydroxyphenylalanine / Q000737:chemistry* / Q000378:metabolism; D046209:Electrophoresis, Microchip / Q000379:methods*; D018698:Glutamic Acid / Q000737:chemistry*; D006801:Humans; D013058:Mass Spectrometry / Q000379:methods*; D012694:Serine / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D018698:Glutamic Acid; D012694:Serine; D004295:Dihydroxyphenylalanine