Simultaneous Determination of Plasma Enrichments of 1-13C- and 15N-Labelled Phenylalanine and Tyrosine

• Published in: Isotopes in environmental and health studies Vol. 34; no. 3; pp. 311 - 316
• Main Authors: Wachter, U., Tugtekin, I., Georgieff, M., Radermacher, P., Vogt, J.
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis Group 1998
• Subjects: Carbon 13; Carbon Isotopes; Gas Chromatography-Mass Spectrometry; GC/MS; nitrogen 15; Nitrogen Isotopes; phenylalanine; Phenylalanine - blood; Tyrosine - blood
• ISSN: 1025-6016; 1477-2639
• DOI: 10.1080/10256019808234065

A methylchloroformate derivative was used for the simultaneous determination of plasma enrichments of 1-
13
C-phenylalanine, 1-
13
C-tyrosine,
15
N-phenylalanine and
15
N-tyrosine by gas chromatography/mass spectrometry. All four tracer enrichments could be measured in a single GC run. A specific ion fragment was obtained for each tracer. This approach allowed an easy determination of the "tracer to tracee ratios". Each ion fragment could be measured with an appropriate single-to-noise ratio and precision in samples obtained from 100 μl plasma. The derivatization consists of a fast one-step reaction. Therefore it is well suited for studies involving a large number of samples, such as non-steady state bolus studies.