title: Chiral separation of N-methyl-DL-aspartic acid in rat brain tissue as N-ethoxycarbonylated (S)-(+)-2-octyl ester derivatives by GC-MS.
abstract: A selective and sensitive analytical method was developed for enantiomeric separation and determination of N-methyl-DL-aspartic acid (NMA). The method involved the conversion of each enantiomer into N-ethoxycarbonylated (S)-(+)-2-octyl ester derivative for the direct separation by gas chromatography-mass spectrometry (GC-MS). The diastereomeric derivatives showed characteristic mass spectral properties for analysis by selected ion monitoring mode (SIM) and enabling enantioseparation on an achiral capillary column. Two enantiomers were baseline separated, and the detection limits for N-methyl-L-aspartic acid (NMLA) and N-methyl-D-aspartic acid (NMDA) were 0.07 and 0.03 ng/g, respectively. When applied to rat brain tissues for absolute configuration of NMA, only NMDA was determined, while NMLA was monitored as lower than the limit of detection.
authors.affiliation: Department of Molecular Science and Technology, Ajou University, Suwon, 443-721, Republic of Korea.
authors.forename: Duc-Toan
authors.initials: DT
authors.lastname: Nguyen
authors.forename: Kyoung-Rae
authors.initials: KR
authors.lastname: Kim
authors.forename: Gwang
authors.initials: G
authors.lastname: Lee
authors.forename: Man-Jeong
authors.initials: MJ
authors.lastname: Paik
mesh_terms: D000818:Animals; D001923:Brain Chemistry; D004952:Esters / Q000737:chemistry* / Q000302:isolation & purification*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D057230:Limit of Detection; D016202:N-Methylaspartate / Q000031:analogs & derivatives* / Q000737:chemistry / Q000302:isolation & purification; D051381:Rats; D015203:Reproducibility of Results; D013237:Stereoisomerism
chemical_list: D004952:Esters; D016202:N-Methylaspartate; C083705:N-methyl-DL-aspartic acid