Determination of 13C Enrichment at Specific Positions of Plasma Glucose by Gas Chromatographic-Mass Spectrometric Analysis of the 1,2:5,6-Diisopropylidene-3-O-Acetyl-α-Furanosyl Derivative
✍ Scribed by F. Rocchiccioli; M. Auclair; P.F. Bougneres
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 467 KB
- Volume
- 218
- Category
- Article
- ISSN
- 0003-2697
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✦ Synopsis
To determine 13C enrichment at specific positions of glucose, plasma samples (50-100 microliters) were deproteinized using ethyl alcohol, centrifuged, and evaporated to dryness, and the residues were derivatized with acetone/H2SO4 (100/1, v/v). After acetylation, the 1,2:5,6-diisopropylidene-3-O-acetyl-alpha-furanosyl derivative was analyzed by gas chromatography-mass spectrometry. The method was tested using mixtures of natural and 13C-labeled glucose molecules. Ions at m/z 113, 114, 143, 144, 287, and 288, corresponding to the C2-C4, C1-C4, and C1-C6 parts of natural or 13C-labeled glucose molecule, respectively, were selectively monitored to determine the 13C content of these fragments. This method was applied to the study of plasma glucose-labeling pattern following the infusion of [3-13C]lactic acid at tracer doses. Assuming equilibration of label through triose-phosphate isomerization in vivo, we determined the 13C enrichment of carbons 1, 2, and 3 of glucose; the values for E1/E3 and E2/E1 ratios of 8.1 and 0.77, respectively, are consistent with those obtained in studies using radioactive tracers.