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Determination of 13 C‐ and 15 N‐enrichment of glutamine by gas chromatography/mass spectrometry and gas chromatography/combustion/isotope ratio mass spectrometry after N(O,S)‐ethoxycarbonyl ethyl ester derivatisation
Author(s) -
Montigon F.,
Boza J. J.,
Fay L. B.
Publication year - 2001
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/1097-0231(20010130)15:2<116::aid-rcm202>3.0.co;2-3
Subject(s) - chemistry , mass spectrometry , chromatography , isotope ratio mass spectrometry , gas chromatography–mass spectrometry , gas chromatography , isotope , derivative (finance) , physics , quantum mechanics , financial economics , economics
To measure 13 C‐ and 15 N‐Gln enrichments in plasma samples by gas chromatography/mass spectrometry (GC/MS) and gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) we investigated the use of the N(O,S)‐ethoxycarbonyl ethyl ester derivative. We found that this derivative is very stable at room temperature, even after 5 days storage. It allows reproducible and accurate 13 C‐ and 15 N‐isotopic enrichment determinations with values of RSD below 0.8 and 3.2% for GC/MS and GC/C/IRMS, respectively. This derivative enables high sample throughput analyses when automated GC/MS and GC/C/IRMS are used. The methodology was applied to measure isotopic enrichments in rat plasma after oral force‐feeding with [2,5‐ 15 N 2 ]‐Gln and in human plasma samples obtained after intravenous infusion of [1‐ 13 C]‐Gln. In rats after oral force‐feeding, we found that the maximal appearance of [2,5‐ 15 N 2 ]‐Gln occurred between 40 and 80 min in the two compartments studied (portal and peripheral blood). In humans infused intravenously with [1‐ 13 C]‐Gln for 4 h, the plateau in 13 C‐Gln enrichments in plasma was reached after 3 h of infusion and coefficients of variation between samples were 1.7 and 12.4% for the two subjects. Using the N(O,S)‐ethoxycarbonyl ethyl ester derivative, 13 C‐ and 15 N‐isotopic enrichment can be determined in the range 2–100 ± 0.3 MPE by GC/MS and 0.3–2 ± 0.02 MPE by GC/C/IRMS. Copyright © 2001 John Wiley & Sons, Ltd.