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Sanchez M, Akoka S. From Percent to Permil: Requirements to Increase Accuracy of Quantitative NMR Measurements. MAGNETIC RESONANCE IN CHEMISTRY : MRC 2025. [PMID: 40400353 DOI: 10.1002/mrc.5531] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2025] [Revised: 04/14/2025] [Accepted: 05/05/2025] [Indexed: 05/23/2025]
Abstract
Quantitative nuclear magnetic resonance (qNMR) can determine the concentration of compounds in solution with remarkable trueness and precision, if the experimental conditions are chosen correctly. However, some users still have difficulty with the correct implementation of these requirements. Knowing which requirements are mandatory and which can be neglected for a given accuracy is one of the major problems. Failure to follow basic requirements s will lead to unreliable results. On the other hand, avoiding unnecessary constraints-for the desired level of trueness and/or precision-can save precious time. The aim of this tutorial is therefore to review in the second section the basic principles of quantitative NMR and explain the impact of different acquisition and processing conditions on trueness and precision. These general guidelines provide both precision and trueness of 1%. To reach 1‰, one has to optimize further their experimental conditions and consider the instrumental imperfections.
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Affiliation(s)
- Margot Sanchez
- Université de Nantes, CNRS, CEISAM UMR 6230, Nantes, France
- RS2D, Mundolsheim, France
| | - Serge Akoka
- Université de Nantes, CNRS, CEISAM UMR 6230, Nantes, France
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2
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Sanchez M, Paris T, Martinez A, Assemat G, Akoka S. The R 2D 3 approach towards fast quantitative NMR: maintaining accuracy and reducing the experimental time. Analyst 2025; 150:1939-1951. [PMID: 40192259 DOI: 10.1039/d4an01369g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/23/2025]
Abstract
Quantitative NMR experiments, especially on low-abundance nuclei such as 13C, can be extremely time-consuming due to the various constraints to ensure the quality of the results: a high number of scans and a long recovery delay. We propose the combination of the DEFT pulse sequence and the R2D2 method, hereafter referred to as R2D3. The addition of DEFT to the R2D2 method reduces the quantitative limitations imposed by partial saturation. The parameters influencing the accuracy were evaluated with simulations and the quantitative performance of R2D3 was assessed by observing the trueness and precision for three different samples. The effects of different processing steps - the number of added rows and apodization - are also discussed. A precision of 1% or less was obtained in almost all the cases, showing that the R2D3 approach can drastically decrease the experimental time while retaining the key aspects of a quantitative experiment. A high time gain factor can be achieved, close to that of INEPT and without its drawbacks, when trueness is less critical than precision. The R2D3 method will particularly benefit qNMR applications based on the observation of heteronuclei and the analysis of a large sample series.
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Affiliation(s)
- Margot Sanchez
- CEISAM, Interdisciplinary Chemistry: Synthesis, Analysis, Modeling, Nantes University-CNRS UMR 6230, 2 rue de la Houssinière, BP 92208, F-44322 Nantes cedex 3, France.
- RS2D, 13 rue Vauban, F-67450 Mundolsheim, France
| | - Thomas Paris
- RS2D, 13 rue Vauban, F-67450 Mundolsheim, France
| | | | - Gaëtan Assemat
- QUAD SYSTEMS, Industriestrasses 31, CH-8305 Dietlikon, Switzerland
| | - Serge Akoka
- CEISAM, Interdisciplinary Chemistry: Synthesis, Analysis, Modeling, Nantes University-CNRS UMR 6230, 2 rue de la Houssinière, BP 92208, F-44322 Nantes cedex 3, France.
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3
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Amr K, Rasheed DM, Khachila M, Farag MA. Production, extraction, and authentication of natural and non-natural vanillin. A comprehensive review and economic future biotechnology perspectives. Food Chem 2025; 466:142249. [PMID: 39612858 DOI: 10.1016/j.foodchem.2024.142249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2024] [Revised: 11/16/2024] [Accepted: 11/23/2024] [Indexed: 12/01/2024]
Abstract
Vanillin is a chief flavoring agent owing to its immense popularity in food, beverage, and pharmaceutical industries. This study holistically dissects vanillin quality control approaches that include conventional, hyphenated, and sensory analyses. Markers to differentiate between authentic, synthetic, and adulterated vanilla are highlighted using hyphenated techniques. Carbon isotope ratio range appears of potential to identify vanillin originating from biosynthetic (C3 plant), synthetic (petroleum) sources, or vanilla pods. Novel extraction methods typically provide greater selectivity, higher purity, shorter extraction times, and ecofriendly attributes compared to conventional methods. Best methods include supercritical fluids (SCF) or natural deep eutectic solvents (NADES) that promoted higher yield of vanillin. The review also highlights the promising avenue of biotransformation, the safest technique for the production of vanilla flavor components, tackling current challenges and emphasizing its potential to meet the market needs for authenticated and high-quality yields of vanillin.
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Affiliation(s)
- Khadiga Amr
- Department of Pharmacognosy, Faculty of Pharmacy, Ain-Shams University, Organization of African Unity Street 1, 11566 Cairo, Egypt
| | - Dalia M Rasheed
- Pharmacognosy Department, Faculty of Pharmacy, October 6 University, 6(th) of October City, Giza, Egypt.
| | - Mariam Khachila
- Undergraduate Program, College of Pharmacy, Cairo University, Cairo, Egypt, Kasr El Aini St, P.B, 11562, Egypt
| | - Mohamed A Farag
- Pharmacognosy Department, College of Pharmacy, Cairo University, Cairo, Egypt, Kasr El Aini St, P.B, 11562, Egypt.
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Rasmussen C, Hoffman D. Fingerprinting Organofluorine Molecules via Position-Specific Isotope Analysis. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024. [PMID: 39023375 DOI: 10.1021/acs.est.4c02250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Organofluorine substances are found in a wide range of materials and solvents commonly used in industry and homes, as well as pharmaceuticals and pesticides. In the environment, organofluorine molecules are now recognized as an important class of anthropogenic pollutants. Fingerprinting organofluorine compounds via their carbon isotope ratios (13C/12C) is crucial for correlating molecules with their source. Here we apply a 19F nuclear magnetic resonance spectroscopy (NMR) technique to obtain the first position-specific carbon isotope ratios for a diverse set of organofluorine molecules. In contrast to traditional isotope ratio mass spectrometry, the 19F NMR method provides 13C/12C isotope ratios at each carbon position where a C-F bond is present, and does not require fragmentation or combustion to CO2, overcoming challenges posed by the robust C-F covalent bonds. The method was validated with 2,2,2-trifluoroethanol, and applied to analyze heptafluorobutanoic acid, 5-fluorouracil and fipronil. Results reveal distinct intramolecular carbon isotope distributions, enabling differentiation of chemically identical molecules. Notably, the NMR method accurately analyzes carbon isotopes within target molecules despite impurities. Potential applications include the detection of counterfeit products and drugs, and ultimately pollution tracking in the environment.
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Affiliation(s)
- Cornelia Rasmussen
- Institute for Geophysics, The University of Texas at Austin, J. J. Pickle Research Campus, 10601 Exploration Way, Austin, Texas 78758, United States
| | - David Hoffman
- Department of Molecular Biosciences, The University of Texas at Austin, 100 East 24th Street, Austin, Texas 78712, United States
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5
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Hoffman DW, Rasmussen C. Position-specific carbon stable isotope analysis of glyphosate: isotope fingerprinting of molecules within a mixture. Anal Bioanal Chem 2024; 416:3847-3856. [PMID: 38740591 DOI: 10.1007/s00216-024-05326-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2024] [Revised: 04/27/2024] [Accepted: 04/30/2024] [Indexed: 05/16/2024]
Abstract
Glyphosate [N-(phosphonomethyl) glycine] is a widely used herbicide and a molecule of interest in the environmental sciences, due to its global use in agriculture and its potential impact on ecosystems. This study presents the first position-specific carbon isotope (13C/12C) analyses of glyphosates from multiple sources. In contrast to traditional isotope ratio mass spectrometry (IRMS), position-specific analysis provides 13C/12C ratios at individual carbon atom positions within a molecule, rather than an average carbon isotope ratio across a mixture or a specific compound. In this work, glyphosate in commercial herbicides was analyzed with only minimal purification, using a nuclear magnetic resonance (NMR) spectroscopy method that detects 1H nuclei with bonds to either 13C or 12C, and isolates the signals of interest from other signals in the mixture. Results demonstrate that glyphosate from different sources can have significantly different intramolecular 13C/12C distributions, which were found to be spread over a wide range, with δ13C Vienna Peedee Belemnite (VPDB) values of -28.7 to -57.9‰. In each glyphosate, the carbon with a bond to the phosphorus atom was found to be depleted in 13C compared to the carbon at the C2 position, by 4 to 10‰. Aminomethylphosphonic acid (AMPA) was analyzed for method validation; AMPA contains only a single carbon position, so the 13C/12C results provided by the NMR method could be directly compared with traditional isotope ratio mass spectrometry. The glyphosate mixtures were also analyzed by IRMS to obtain their average 13C/12C ratios, for comparison with our position-specific results. This comparison revealed that the IRMS results significantly disguise the intramolecular isotope distribution. Finally, we introduce a 31P NMR method that can provide a position-specific 13C/12C ratio for carbon positions with a C-P chemical bond, and the results obtained by 1H and 31P for C3 carbon agree with one another within their analytical uncertainty. These analytical tools for position-specific carbon isotope analysis permit the isotopic fingerprinting of target molecules within a mixture, with potential applications in a range of fields, including the environmental sciences and chemical forensics.
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Affiliation(s)
- David W Hoffman
- Department of Molecular Biosciences, The University of Texas at Austin, 100 East 24th St., Austin, TX, 78712, USA.
| | - Cornelia Rasmussen
- Institute for Geophysics, The University of Texas at Austin, J. J. Pickle Research Campus, 10601 Exploration Way, Austin, TX, 78758, USA
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D’Arrigo P, Rossato LAM, Strini A, Serra S. From Waste to Value: Recent Insights into Producing Vanillin from Lignin. Molecules 2024; 29:442. [PMID: 38257355 PMCID: PMC10818928 DOI: 10.3390/molecules29020442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 01/11/2024] [Accepted: 01/12/2024] [Indexed: 01/24/2024] Open
Abstract
Vanillin, one of the most widely used and appreciated flavoring agents worldwide, is the main constituent of vanilla bean extract, obtained from the seed pods of various members belonging to the Orchidaceae family. Due to the great demand in the food confectionery industry, as well as in the perfume industry, medicine, and more, the majority of vanillin used today is produced synthetically, and only less than one percent of the world's vanilla flavoring market comes directly from the traditional natural sources. The increasing global demand for vanillin requires alternative and overall sustainable new production methods, and the recovery from biobased polymers, like lignin, is an environmentally friendly alternative to chemical synthesis. The present review provides firstly an overview of the different types of vanillin, followed by a description of the main differences between natural and synthetic vanillin, their preparation, the market of interest, and the authentication issues and the related analytical techniques. Then, the review explores the real potentialities of lignin for vanillin production, presenting firstly the well-assessed classical methods and moving towards the most recent promising approaches through chemical, biotechnological and photocatalytic methodologies, together with the challenges and the principal issues associated with each technique.
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Affiliation(s)
- Paola D’Arrigo
- Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, p.zza Leonardo da Vinci 32, 20133 Milan, Italy
- Istituto di Scienze e Tecnologie Chimiche “Giulio Natta”, Consiglio Nazionale delle Ricerche (SCITEC-CNR), via Luigi Mancinelli 7, 20131 Milan, Italy;
| | - Letizia A. M. Rossato
- Department of Chemistry, Materials and Chemical Engineering “Giulio Natta”, Politecnico di Milano, p.zza Leonardo da Vinci 32, 20133 Milan, Italy
| | - Alberto Strini
- Istituto per le Tecnologie della Costruzione, Consiglio Nazionale delle Ricerche (ITC-CNR), via Lombardia 49, 20098 San Giuliano Milanese, Italy;
| | - Stefano Serra
- Istituto di Scienze e Tecnologie Chimiche “Giulio Natta”, Consiglio Nazionale delle Ricerche (SCITEC-CNR), via Luigi Mancinelli 7, 20131 Milan, Italy;
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Greule M, Le PM, Meija J, Mester Z, Keppler F. Comparison of Carbon Isotope Ratio Measurement of the Vanillin Methoxy Group by GC-IRMS and 13C-qNMR. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2024; 35:100-105. [PMID: 38015023 PMCID: PMC10767744 DOI: 10.1021/jasms.3c00327] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Revised: 11/07/2023] [Accepted: 11/09/2023] [Indexed: 11/29/2023]
Abstract
Site-specific carbon isotope ratio measurements by quantitative 13C NMR (13C-qNMR), Orbitrap-MS, and GC-IRMS offer a new dimension to conventional bulk carbon isotope ratio measurements used in food provenance, forensics, and a number of other applications. While the site-specific measurements of carbon isotope ratios in vanillin by 13C-qNMR or Orbitrap-MS are powerful new tools in food analysis, there are a limited number of studies regarding the validity of these measurement results. Here we present carbon site-specific measurements of vanillin by GC-IRMS and 13C-qNMR for methoxy carbon. Carbon isotope delta (δ13C) values obtained by these different measurement approaches demonstrate remarkable agreement; in five vanillin samples whose bulk δ13C values ranged from -31‰ to -26‰, their δ13C values of the methoxy carbon ranged from -62.4‰ to -30.6‰, yet the difference between the results of the two analytical approaches was within ±0.6‰. While the GC-IRMS approach afforded up to 9-fold lower uncertainties and required 100-fold less sample compared to the 13C-qNMR, the 13C-qNMR is able to assign δ13C values to all carbon atoms in the molecule, not just the cleavable methoxy group.
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Affiliation(s)
- Markus Greule
- Institute
of Earth Sciences, Heidelberg University, Im Neuenheimer Feld 234-236, 69120 Heidelberg, Germany
| | - Phuong Mai Le
- Metrology, National
Research Council Canada, 1200 Montreal Road, Ottawa, ON K1A
0R6, Canada
| | - Juris Meija
- Metrology, National
Research Council Canada, 1200 Montreal Road, Ottawa, ON K1A
0R6, Canada
| | - Zoltán Mester
- Metrology, National
Research Council Canada, 1200 Montreal Road, Ottawa, ON K1A
0R6, Canada
| | - Frank Keppler
- Institute
of Earth Sciences, Heidelberg University, Im Neuenheimer Feld 234-236, 69120 Heidelberg, Germany
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Renou S, Grand M, Daux V, Tcherkez G, Akoka S, Remaud G. NMR-Based Method for Intramolecular 13C Distribution at Natural Abundance Adapted to Small Amounts of Glucose. Anal Chem 2023. [PMID: 37413690 DOI: 10.1021/acs.analchem.2c05542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/08/2023]
Abstract
Quantitative nuclear magnetic resonance (NMR) for isotopic measurements, known as irm-NMR (isotope ratio measured by NMR), is well suited for the quantitation of 13C-isotopomers in position-specific isotope analysis and thus for measuring the carbon isotope composition (δ13C, mUr) in C-atom positions. Irm-NMR has already been used with glucose after derivatization to study sugar metabolism in plants. However, up to now, irm-NMR has exploited a "single-pulse" sequence and requires a relatively large amount of material and long experimental time, precluding many applications with biological tissues or extracts. To reduce the required amount of sample, we investigated the use of 2D-NMR analysis. We adapted and optimized the NMR sequence so as to be able to analyze a small amount (10 mg) of a glucose derivative (diacetonide glucofuranose, DAGF) with a precision better than 1 mUr at each C-atom position. We also set up a method to correct raw data and express 13C abundance on the usual δ13C scale (δ-scale). In fact, due to the distortion associated with polarization transfer and spin manipulation during 2D-NMR analyses, raw 13C abundance is found to be on an unusual scale. This was compensated for by a correction factor obtained via comparative analysis of a reference material (commercial DAGF) using both previous (single-pulse) and new (2D) sequences. Glucose from different biological origins (CO2 assimilation metabolisms of plants, namely, C3, C4, and CAM) was analyzed with the two sequences and compared. Validation criteria such as selectivity, limit of quantification, precision, trueness, and robustness are discussed, including in the framework of green analytical chemistry.
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Affiliation(s)
- Sophie Renou
- CEISAM, CNRS, Nantes Université, F-44322 Nantes, France
| | | | - Valérie Daux
- Laboratoire des Sciences du Climat et de l'Environnement, CEA - CNRS - UVSQ - Université Paris-Saclay, 91191 Gif-sur-Yvette, France
| | - Guillaume Tcherkez
- Research School of Biology, Australian National University, Acton, 2601 Canberra, ACT, Australia
- Institut de Recherche en Horticulture et Semences, Université d'Angers, INRAe, 42 rue Georges Morel, 49070 Beaucouzé, France
| | - Serge Akoka
- CEISAM, CNRS, Nantes Université, F-44322 Nantes, France
| | - Gérald Remaud
- CEISAM, CNRS, Nantes Université, F-44322 Nantes, France
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