Application of 13C Quantitative NMR Spectroscopy to Isotopic Analyses for Vanillin Authentication Source

The carbon stable isotope ratio (δ13C) is a valuable chemical parameter in the investigation of the geographic origin, quality, and authenticity of foods. The aim of this study is the evaluation of the feasibility of 13C-NMR (Nuclear Magnetic Resonance) spectroscopy to determine the carbon stable isotope ratio, at natural abundance, of small organic molecules, such as vanillin, without the use of IRMS (Isotope Ratio Mass Spectrometry). The determination of vanillin origin is an active task of research, and differentiating between its natural and artificial forms is important to guarantee the quality of food products. To reach our goal, nine vanillin samples were analyzed using both 13C quantitative NMR spectroscopy (under optimized experimental conditions) and IRMS, and the obtained δ13C values were compared using statistical analysis (linear regression, Bland–Altman plot, and ANOVA (analysis of variance)). The results of our study show that 13C-NMR spectroscopy can be used as a valuable alternative methodology to determine the bulk carbon isotope ratio and to identify the origin of vanillin. This makes it attractive for the analysis in the same experiment of site-specific and total isotope effects for testing authenticity, quality, and typicality of food samples. Moreover, the improvement of NMR spectroscopy makes it possible to avoid the influence of additives on carbon stable isotope ratio analysis and to clearly identify fraud and falsification in commercial samples.

Associations Between Sugars Intakes and Urinary Sugars Excretion and Carbon Stable Isotope Ratios in Red Blood Cells as Biomarkers of Sugars Intake in a Predominantly Māori Population

Determining the extent to which added sugars intake contribute to non-communicable disease in various populations is challenging because it is difficult to accurately measure intakes. Biomarkers may provide a reliable and easily measured method of assessing intakes. In a predominantly Māori population we compared various sugars intake estimates derived from a 36 item sugar-specific food frequency questionnaire (FFQ) with biomarkers of sugars intake; urinary sugars excretion in random spot collections (n = 153) and carbon stable isotope ratios (n = 36) in red blood cells (RBCs, δ13CRBC) and in the alanine fraction of the RBCs (δ13Calanine). Estimated 24 h urinary sucrose+fructose excretion was statistically significantly correlated with intakes of total sugars (r = 0.23), sucrose (r = 0.26) and added sugars from sugar-sweetened beverages (SSBs; r = 0.26). δ13Calanine was correlated with added sugars (r = 0.40). In log linear multiple regression models adjusted with HbA1C and eGFR δ13Calanine predicted added sugars intakes (r2 = 0.29) and estimated 24 h urinary sucrose+fructose excretion predicted intakes of total sugars (r2 = 0.14), sucrose (r2 = 0.17), added sugars (r2 = 0.17) and sugars from SSBs (r2 = 0.14). These biomarkers have potential for improving assessment of sugars intake in New Zealand populations enabling monitoring of the effectiveness of sugar reduction strategies designed to reduce risk of NCDs. However, further validation is required to confirm these preliminary findings.

Carbon isotope trends in north-west European mosasaurs (Squamata; Late Cretaceous)

The carbon stable isotope composition (δ13C) of tooth enamel in mosasaurid squa-mates reflects aspects of their diet and diving behaviour. Here we present new δ13C data for such marine squamates from the Maastrichtian of Denmark and compare these with results obtained in previous studies from the lower-latitude type area of the Maastrichtian Stage (latest Cretaceous; 72.1–66.0 Ma) in the south-east Nether-lands and north-east Belgium. For the Danish samples, there is a weak correlation between mosasaur body size and δ13C values, with larger-sized taxa having lower δ13C values, comparable to what has previously been observed for mosasaurs from the Maastrichtian type area.

Termination of Organic-Rich Accumulation of the Oceanic Anoxic Event 2 in the Deep-Water Carpathian Basins Based on Carbon Stable Isotope Data

Organic-rich black shales intercalated with green radiolarian shales and bentonites, 2.2 m thick, represent an equivalent of the Bonarelli Level in the Outer Carpathian deep-water succession. Carbon stable isotope data from four sections in the Outer Carpathians show that termination of organic-rich accumulation, related to the oceanic anoxic event 2 (OAE2), occurred at the same time in this part of the Western Tethys. The excellent marker of this event is a first horizon of Fe–Mn layer (nodules), a few centimeters thick, directly covering the youngest black shale layer of the Bonarelli-equivalent Level, which is regarded as the regional chronohorizon. The youngest succession of the organic-rich shales, ca. 30 cm thick, corresponds to the latest Cenomanian interval of δ13Corg values displaying a negative trend, which represents a terminal part within the OAE2 carbon isotope excursion. A deep negative shift which ends this falling trend, close to the Cenomanian–Turonian boundary in δ13C curves from many sections around the world, is not visible in the Outer Carpathian successions. The reason for this was the long period of stratigraphic condensation, which is reflected in the ferromanganese sediments of this area.