Determination of (13C)urea enrichment by gas chromatography/mass spectrometry and gas chromatography/isotope ratio mass spectrometry

✍ Scribed by Michel Beylot; France David; Yadh Khalfallah; Sylvie Normand; Valerie Large; Henri Brunengraber

• Publisher: John Wiley and Sons
• Year: 1994
• Tongue: English
• Weight: 354 KB
• Volume: 23
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/bms.1200230808

✦ Synopsis

We present gas chromatographic/mass spectrometric and gas chromatographic/isotope ratio mass spectrometric assays of the 13C enrichment of plasma urea converted to its dimethylaminomethylene derivative. The limits of sensitivity of the two techniques are 0.2% and 0.02%, respectively. The techniques were tested in rats and humans infused with (13C)urea or (3-'3C)lactate. (13C)Urea enrichment during the infusion of (3-"C)lactate in humans was not detectable by gas chromatography/mass spectrometry but was easily measured by gas chromatography/isotope ratio mass spectrometry. These assays should be useful for clinical investigations, in which the incorporation of a ('3C)gluconeogenic substrate into glucose must be corrected for the incorporation of "COZ derived from the oxidation of the substrate. This correction involves measuring the low-level "C enrichment of urea.