On-line high-precision carbon position-specific stable isotope analysis: a review

Since the first commercial availability of gas chromatographs coupled with a combustion furnace and an isotope ratio mass spectrometry in 1990, compound-specific stable isotope analysis of organic molecules has been at the origin of scientific breakthroughs in a wide range of research fields. The presence of non-reacting atoms, however, can mask changes in molecular stable isotopic signatures; position-specific isotope analysis (PSIA) is the study of intramolecular isotopic variations. After a brief consideration of the potential and prospect of this new level in isotopic studies, in this study, we review few existing custom-built systems for on-line PSIA using continuous flow isotope ratio mass spectrometry instrumentation and how researchers have addressed issues related to this technique. Molecular fragmentation processes observed and optimised for various molecules are also discussed for on-line PSIA, as it would provide information on their application to new compounds

Isotopic characterization of selected fruit juices - determination of authenticity on the basis of deuterium content by SNIF-NMR

Obsah deuteria v cukrech v ovoci je ovlivněn hlavně botanickým a částečně také geografickým původem ovoce. Informaci o původu ovoce poskytuje ethanol po fermentaci cukrů. Obsah deuteria na methylové skupině ethanolu se liší v závislosti na botanickém původu ovoce. SNIF NMR - nukleární magnetická rezonance sledující distribuci izotopů na různých místech v molekule je specifická metoda pro stanovení zastoupení deuteria (izotopový poměr D/H) v malých molekulách, např. v ethanolu. Tato izotopová technika je běžně používana pro stanovení nepovoleného přídavku cukru v ovocných nápojích (víno, ovocné džusy...). V této diplomové práci bylo pomocí SNIF NMR analyzováno pět druhů ovoce (jablka, pomeranče, grapefruity, ananasy a hroznové víno) dostupných na trhu v České republice. Tato data jsou porovnávána s hodnotami změřenými pro komerčně dostupné ovocné džusy a nektary.The deuterium content of sugar in fruits is influenced mainly by two factors – the botanical and also the geographical origin of the fruit. The information of the fruit origin is kept even after fermentation of the sugar, in the molecules of ethanol. The deuterium content on the methyl group of ethanol then varies depending upon the botanical origin of the fruit. SNIF-NMR (Site-specific Natural Isotope Fractionation – Nuclear Magnetic Resonance) is a specific method for determination of the deuterium isotopic ratio (D/H) in small molecules, e.g. ethanol. This isotopic technique is widely used for determination of sugar adulteration of fruit-based beverages (wines, fruit juices..). In this thesis, the authentic samples of five different fruits (apples, oranges, grapefruits, pineapples and grapes) available in the Czech market have been collected and analyzed by SNIF-NMR. The results are presented as well as the comparison to some commercially available fruit juices and nectars.

Certification of the Deuterium-to-Hydrogen (D/H) amount-of-substance ratio in a 1,1,3,3 - tetramethylurea batch: Certified Reference Material STA-003m

This report describes the production of a tetramethylurea (TMU) reference material (STA-003m), certified for its deuterium-to-hydrogen (D/H) amount-of-substance ratio. The material is to be used as an internal standard in site-specific natural isotope fractionation – nuclear magnetic resonance (SNIF-NMR) spectrometry measurements for determining the D/H amount-of-substance ratios of ethanol distilled from wines, an important measure in wine authenticity testing (Commission Regulation 2676/90). Commercially obtained TMU with a sufficiently high D/H amount-of-substance ratio (>120 x 10-6) was first purified by removing most of the residual water and then filled into amber glass bottles of 500 mL. Between-unit homogeneity was quantified and stability during dispatch and storage were assessed in accordance with ISO Guide 35:2006. Batch characterisation was accomplished by comparing STA-003m samples with samples of the TMU master batch (IRMM-425) under repeatability conditions and by adhering to the SNIF-NMR technique. The certified value was calculated as the unweighted mean of 18 individual results obtained on 3 different NMR appliances. The uncertainty of the certified value was estimated in compliance with ISO Guide 98-3, Guide to the Expression of Uncertainty in Measurement (GUM); it includes contributions from possible inhomogeneity, instability, and characterisation.JRC.D.2-Standards for Innovation and sustainable Developmen

Studio dell'impronta isotopica del deuterio di oli alimentari mediante la spettroscopia NMR del 2H e 1H

A report is given on 2H and 1H NMR investigations of a number of triacylglycerol mixtures of edible oils and squalene samples extracted from extra virgin olive oil, shark liver and synthetic. The average numbers of hydrogen and deuterium for the olefinic, methylene and methyl sites were determined, and some parameters describing the different fractionation of deuterium in the various sites were obtained. The results have been discussed in terms of the biosynthesis steps involved in the elongation and desaturation processes of the fatty acids, and in the condensation and reduction processes of the squalene. From a principal components analysis distinct domains have been found for the squalene samples from shark liver, olive oil and synthetic

Food adulteration and traceability tests using stable carbon isotope technologies

Due to the fractionation of stable carbon isotopes in plant photosynthesis, bio-decomposition processes, environmental factors, plant physiology, geographical factors, climatic conditions and agricultural practices, different foods exhibit significant differences in stable carbon isotope ratios. Therefore, stable carbon isotope ratio analysis (SCIRA) presents an effective tool for detecting food adulteration and food traceability control. In addition, stable carbon isotopes can frequently be used as markers to identify veterinary drug residues, pesticide residues and toxic substances remaining in foods by isotope dilution mass spectrometry (IDMS). The emphasis of this review, which will help readers to modify stable carbon isotope technologies more easily and extend their application in adulteration and traceability for foods, is on the characteristics of various instruments and the data processing methods in SCIRA and IDMS technologies. The latest research is also reviewed and highlighted. This paper reviews potential applications of these technologies to improve current food detection and protect consumers’ rights

NMR spectroscopy in wine authentication: an official control perspective

6FESR 2014-2020 Program of the Autonomous Province of Trento (Italy) with EU co-financing. (Fruitomics)openInternationalInternational coauthor/editorWine authentication is vital in identifying malpractice and fraud, and various physical and chemical analytical techniques have been employed for this purpose. Besides wet chemistry, these include chromatography, isotopic ratio mass spectrometry, optical spectroscopy and nuclear magnetic resonance (NMR) spectroscopy, which have been applied in recent years in combination with chemometric approaches. For many years, 2H NMR spectroscopy was the method of choice and achieved official recognition in the detection of sugar addition to grape products. Recently, 1H NMR spectroscopy, a simpler and faster method (in terms of sample preparation), has gathered more and more attention in wine analysis, even if it still lacks official recognition. This technique makes targeted quantitative determination of wine ingredients and non-targeted detection of the metabolomic fingerprint of a wine sample possible. This review summarizes the possibilities and limitations of 1H NMR spectroscopy in analytical wine authentication, by reviewing its applications as reported in the literature. Examples of commercial and open source solutions combining NMR spectroscopy and chemometrics are also examined herein, together with its opportunities of becoming an official method.openSolovyev, P.; Fauhl-Hassek, C.; Riedl, J.; Esslinger, S.; Bontempo, L.; Camin, F.Solovyev, P.; Fauhl-Hassek, C.; Riedl, J.; Esslinger, S.; Bontempo, L.; Camin, F

Insights into the stable isotope ratio variability of hybrid grape varieties: a preliminary study

Background: Official stable isotope databases, based on the analysis of (D/H)I ethanol , (D/H)II ethanol , δ13 Cethanol and δ18 Owater of wine, are an indispensable tool for establishing the limits beyond which the mislabeling or the addition of sugar and/or water in wine production can be detected. The present study investigates, for the first time, whether the use of hybrid varieties instead of European Vitis vinifera for wine production can have an impact on the stable isotope ratios. Results: The analyses were performed by isotope ratio mass spectrometry and site-specific natural isotope fractionation by nuclear magnetic resonance, in accordance with the official methods of the International Organization of Grapes and Wine. The comparison shows the tendency of some stable isotope ratios of hybrid varieties, in particular (D/H)I , to deviate from the regional averages of the V. vinifera samples. Notably, Baron, Monarch and Regent showed significantly different values at one of the two sampling sites. Particularly high δ13 C values characterize Helios compared to other hybrid varieties. Conclusion: For the first time, and from an isotopic point of view, the present study investigates the wine obtained from hybrid varieties, showing that further attention should be paid to their interpretation, on the basis of the database established according to the European Regulation 2018/273. © 2022 Society of Chemical Industry

Certified reference materials for food authenticity

Factsheet summarising the CRMs from the JRC-IRMM for food authenticityJRC.D-Institute for Reference Materials and Measurements (Geel

Application of 13C Quantitative NMR Spectroscopy to isotopic analyses for vanillin authentication source

6openInternationalBothThe 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 samplesopenPironti, C.; Ricciardi, M.; Motta, O.; Camin, F.; Bontempo, L.; Proto, A.Pironti, C.; Ricciardi, M.; Motta, O.; Camin, F.; Bontempo, L.; Proto, A