title: Site-specific 13C content by quantitative isotopic 13C nuclear magnetic resonance spectrometry: a pilot inter-laboratory study.
abstract: Isotopic (13)C NMR spectrometry, which is able to measure intra-molecular (13)C composition, is of emerging demand because of the new information provided by the (13)C site-specific content of a given molecule. A systematic evaluation of instrumental behaviour is of importance to envisage isotopic (13)C NMR as a routine tool. This paper describes the first collaborative study of intra-molecular (13)C composition by NMR. The main goals of the ring test were to establish intra- and inter-variability of the spectrometer response. Eight instruments with different configuration were retained for the exercise on the basis of a qualification test. Reproducibility at the natural abundance of isotopic (13)C NMR was then assessed on vanillin from three different origins associated with specific δ (13)Ci profiles. The standard deviation was, on average, between 0.9 and 1.2‰ for intra-variability. The highest standard deviation for inter-variability was 2.1‰. This is significantly higher than the internal precision but could be considered good in respect of a first ring test on a new analytical method. The standard deviation of δ (13)Ci in vanillin was not homogeneous over the eight carbons, with no trend either for the carbon position or for the configuration of the spectrometer. However, since the repeatability for each instrument was satisfactory, correction factors for each carbon in vanillin could be calculated to harmonize the results.
authors.affiliation: Firmenich SA, Corporate R&D Division, Geneva 8, Switzerland.
authors.forename: Alain
authors.initials: A
authors.lastname: Chaintreau
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Fieber
authors.forename: Horst
authors.initials: H
authors.lastname: Sommer
authors.forename: Alexis
authors.initials: A
authors.lastname: Gilbert
authors.forename: Keita
authors.initials: K
authors.lastname: Yamada
authors.forename: Naohiro
authors.initials: N
authors.lastname: Yoshida
authors.forename: Alain
authors.initials: A
authors.lastname: Pagelot
authors.forename: Detlef
authors.initials: D
authors.lastname: Moskau
authors.forename: Aitor
authors.initials: A
authors.lastname: Moreno
authors.forename: Jürgen
authors.initials: J
authors.lastname: Schleucher
authors.forename: Fabiano
authors.initials: F
authors.lastname: Reniero
authors.forename: Margaret
authors.initials: M
authors.lastname: Holland
authors.forename: Claude
authors.initials: C
authors.lastname: Guillou
authors.forename: Virginie
authors.initials: V
authors.lastname: Silvestre
authors.forename: Serge
authors.initials: S
authors.lastname: Akoka
authors.forename: Gérald S
authors.initials: GS
authors.lastname: Remaud
mesh_terms: D001547:Benzaldehydes / Q000737:chemistry; D002247:Carbon Isotopes / Q000737:chemistry*; D007753:Laboratories; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation* / Q000379:methods*; D010865:Pilot Projects; D015203:Reproducibility of Results
chemical_list: D001547:Benzaldehydes; D002247:Carbon Isotopes; C100058:vanillin
keywords: Collaborative study; Intra molecular (13)C isotope distribution; Quantitative Nuclear Magnetic Resonance spectrometry; Vanillin