Impact of the deuterium isotope effect on the accuracy of 13C NMR measurements of site-specific isotope ratios at natural abundance in glucose.
The application of isotope ratio methods in authenticity and traceability relies on the accuracy and robustness of the methodology employed. An unexpected source of error has now been identified, which can introduce major and variable inaccuracies into the determination of site-specific isotope ratio measurement by quantitative (13)C NMR spectrometry if not correctly controlled. This is the isotope chemical shift effect, which comes into play when hydrogen atoms in the target molecule enter into exchange with deuterated water present at trace levels in the deuterated solvent used as the frequency lock. Even at a level of contamination as low as 0.02%, an error of 5‰ can be introduced, fivefold the required accuracy of 1‰. How to avoid this source of error is discussed.
Gilbert
Alexis
A
Elucidation of Biosynthesis by Isotopic Spectrometry Group, Unit for Interdisciplinary Chemistry: Synthesis, Analysis, Modelling (CEISAM), CNRS-University of Nantes UMR6230, 2 rue de la Houssinière, BP 92208, Nantes 44322 Cedex 3, France.
Silvestre
Virginie
V
Robins
Richard J
RJ
Remaud
Gérald S
GS
D002247:Carbon Isotopes / Q000737:chemistry; D003903:Deuterium / Q000737:chemistry*; D003951:Diagnostic Errors; D005947:Glucose / Q000032:analysis / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*
D002247:Carbon Isotopes; D003903:Deuterium; D005947:Glucose