Chiral separation and determination of excitatory amino acids in brain samples by CE-LIF using dual cyclodextrin system

Chiral capillary electrophoresis method has been developed to separate aspartate and glutamate enantiomers to investigate the putative neuromodulator function of d -Asp in the central nervous system. To achieve appropriate detection sensitivity fluorescent derivatization with 4-fluoro-7-nitro-2,1,3-...

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Veröffentlicht in:Analytical and bioanalytical chemistry 2012-11, Vol.404 (8), p.2363-2368
Hauptverfasser: Wagner, Zsolt, Tábi, Tamás, Jakó, Tamás, Zachar, Gergely, Csillag, András, Szökő, Éva
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Sprache:eng
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Zusammenfassung:Chiral capillary electrophoresis method has been developed to separate aspartate and glutamate enantiomers to investigate the putative neuromodulator function of d -Asp in the central nervous system. To achieve appropriate detection sensitivity fluorescent derivatization with 4-fluoro-7-nitro-2,1,3-benzoxadiazole and laser-induced fluorescence detection was applied. Although, simultaneous baseline separation of the two enantiomer pairs could be achieved by using 3 mM 6-monodeoxy-6-mono(3-hydroxy)propylamino-β-cyclodextrin (HPA-β-CD), further improvement of the chemical selectivity was required because of the high excess of l -enantiomers in real samples to be analyzed. The system selectivity was fine-tuned by combination of 8 mM heptakis(2,6-di- O -methyl)-β-cyclodextrin and 5 mM HPA-β-CD in order to increase the resolution between aspartate and glutamate enantiomers. The method was validated for biological application. The limits of detection for d -Asp and d -Glu were 17 and 9 nM, respectively, while the limit of quantification for both analytes was 50 nM. This is the lowest quantification limit reported so far for NBD-tagged d -Asp and d -Glu obtained by validated capillary electrophoresis laser-induced fluorescence method. The applicability of the method was demonstrated by analyzing brain samples of 1-day-old chickens. In all the studied brain areas, the d -enantiomer contributed 1–2 % of the total aspartate content, corresponding to 17–45 nmol/g wet tissue.
ISSN:1618-2642
1618-2650
DOI:10.1007/s00216-012-6384-x