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Applications and Method Developments in NMR – from Benchtop to High Field NMR Spectroscopy

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Analytical Chemistry".

Deadline for manuscript submissions: closed (31 July 2023) | Viewed by 20977

Special Issue Editor


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Guest Editor
Department of Chemistry and Environmental NMR Centre, University of Toronto, 1265 Military Trail, Toronto, ON M1C 1A4, Canada
Interests: NMR spectroscopy; metabolomics; structure elucidation; environmental science; mixture deconvolution

Special Issue Information

Dear Colleagues,

Recent advances in technology have brought forth new applications and developments in the NMR community. No longer does an NMR spectrometer require a large footprint; it is now possible to have the entire NMR spectrometer on a lab bench. Therefore, this brings a new perspective on NMR method developments that focus on a range of magnetic fields, from benchtop to high-field NMR spectrometers. The goal of this issue is to bring together developments and applications that cover a range of magnetic field strengths, allowing for a complete overview of the current development in NMR spectroscopy for both novice and advanced users.  

Prof. Dr. Ronald Soong
Guest Editor

Manuscript Submission Information

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Keywords

  • pulse sequence development
  • hardware design
  • benchtop NMR
  • biomolecular NMR
  • solid-state NMR
  • natural product
  • food chemistry
  • material science

Published Papers (4 papers)

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Research

14 pages, 2865 KiB  
Article
Exploring the Potential of Broadband Complementary Metal Oxide Semiconductor Micro-Coil Nuclear Magnetic Resonance for Environmental Research
by Daniel H. Lysak, Marco Grisi, Kathryn Marable, Gaurasundar M. Conley, Carl A. Michal, Vincent Moxley-Paquette, William W. Wolff, Katelyn Downey, Flavio V. C. Kock, Peter M. Costa, Kiera Ronda, Tiago B. Moraes, Katrina Steiner, Luiz A. Colnago and Andre J. Simpson
Molecules 2023, 28(13), 5080; https://doi.org/10.3390/molecules28135080 - 29 Jun 2023
Cited by 2 | Viewed by 1575
Abstract
With sensitivity being the Achilles’ heel of nuclear magnetic resonance (NMR), the superior mass sensitivity offered by micro-coils can be an excellent choice for tiny, mass limited samples such as eggs and small organisms. Recently, complementary metal oxide semiconductor (CMOS)-based micro-coil transceivers have [...] Read more.
With sensitivity being the Achilles’ heel of nuclear magnetic resonance (NMR), the superior mass sensitivity offered by micro-coils can be an excellent choice for tiny, mass limited samples such as eggs and small organisms. Recently, complementary metal oxide semiconductor (CMOS)-based micro-coil transceivers have been reported and demonstrate excellent mass sensitivity. However, the ability of broadband CMOS micro-coils to study heteronuclei has yet to be investigated, and here their potential is explored within the lens of environmental research. Eleven nuclei including 7Li, 19F, 31P and, 205Tl were studied and detection limits in the low to mid picomole range were found for an extended experiment. Further, two environmentally relevant samples (a sprouting broccoli seed and a D. magna egg) were successfully studied using the CMOS micro-coil system. 13C NMR was used to help resolve broad signals in the 1H spectrum of the 13C enriched broccoli seed, and steady state free precession was used to improve the signal-to-noise ratio by a factor of six. 19F NMR was used to track fluorinated contaminants in a single D. magna egg, showing potential for studying egg–pollutant interactions. Overall, CMOS micro-coil NMR demonstrates significant promise in environmental research, especially when the future potential to scale to multiple coil arrays (greatly improving throughput) is considered. Full article
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19 pages, 2256 KiB  
Article
Exploring Proton-Only NMR Experiments and Filters for Daphnia In Vivo: Potential and Limitations
by Kiera Ronda, Katelyn Downey, Amy Jenne, Monica Bastawrous, William W. Wolff, Katrina Steiner, Daniel H. Lysak, Peter M. Costa, Myrna J. Simpson, Karl J. Jobst and Andre J. Simpson
Molecules 2023, 28(12), 4863; https://doi.org/10.3390/molecules28124863 - 20 Jun 2023
Cited by 2 | Viewed by 1276
Abstract
Environmental metabolomics provides insight into how anthropogenic activities have an impact on the health of an organism at the molecular level. Within this field, in vivo NMR stands out as a powerful tool for monitoring real-time changes in an organism’s metabolome. Typically, these [...] Read more.
Environmental metabolomics provides insight into how anthropogenic activities have an impact on the health of an organism at the molecular level. Within this field, in vivo NMR stands out as a powerful tool for monitoring real-time changes in an organism’s metabolome. Typically, these studies use 2D 13C-1H experiments on 13C-enriched organisms. Daphnia are the most studied species, given their widespread use in toxicity testing. However, with COVID-19 and other geopolitical factors, the cost of isotope enrichment increased ~6–7 fold over the last two years, making 13C-enriched cultures difficult to maintain. Thus, it is essential to revisit proton-only in vivo NMR and ask, “Can any metabolic information be obtained from Daphnia using proton-only experiments?”. Two samples are considered here: living and whole reswollen organisms. A range of filters are tested, including relaxation, lipid suppression, multiple-quantum, J-coupling suppression, 2D 1H-1H experiments, selective experiments, and those exploiting intermolecular single-quantum coherence. While most filters improve the ex vivo spectra, only the most complex filters succeed in vivo. If non-enriched organisms must be used, then, DREAMTIME is recommended for targeted monitoring, while IP-iSQC was the only experiment that allowed non-targeted metabolite identification in vivo. This paper is critically important as it documents not just the experiments that succeed in vivo but also those that fail and demonstrates first-hand the difficulties associated with proton-only in vivo NMR. Full article
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11 pages, 2622 KiB  
Article
Detection of Vegetable Oil Adulteration in Pre-Grated Bovine Hard Cheeses via 1H NMR Spectroscopy
by Colleen L. Ray, James A. Gawenis, Madison P. Bylo, Jonny Pescaglia and C. Michael Greenlief
Molecules 2023, 28(3), 920; https://doi.org/10.3390/molecules28030920 - 17 Jan 2023
Viewed by 14169
Abstract
Adulteration of food products is a widespread problem of great concern to society and dairy products are no exception to this. Due to new methods of adulteration being devised in order to circumvent existing detection methods, new detection methods must be developed to [...] Read more.
Adulteration of food products is a widespread problem of great concern to society and dairy products are no exception to this. Due to new methods of adulteration being devised in order to circumvent existing detection methods, new detection methods must be developed to counter fraud. Bovine hard cheeses such as Asiago, Parmesan, and Romano are widely sold and consumed in pre-grated form for convenience. Due to being processed products, there is ample opportunity for the introduction of inexpensive adulterants and as such, there is concern regarding the authenticity of these products. An analytical method was developed using a simple organic extraction to verify the authenticity of bovine hard cheese products by examining the lipid profile of these cheeses via proton Nuclear Magnetic Resonance (NMR) spectroscopy. In this study, 52 samples of pre-grated hard cheese were analyzed as a market survey and a significant number of these samples were found to be adulterated with vegetable oils. This method is well suited to high throughput analysis of these products and relies on ratiometrics of the lipids in the samples themselves. Genuine cheeses were found to have a very consistent lipid profile from sample to sample, improving the power of this approach to detect vegetable oil adulteration. The method is purely ratiometric with no need for internal or external references, reducing sample preparation time and reducing the potential for the introduction of error. Full article
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16 pages, 1950 KiB  
Article
The Aging Process: A Metabolomics Perspective
by Alex Castro, Étore F. Signini, Juliana Magalhães De Oliveira, Maria Carolina Bezerra Di Medeiros Leal, Patrícia Rehder-Santos, Juliana C. Millan-Mattos, Vinicius Minatel, Camila B. F. Pantoni, Regina V. Oliveira, Aparecida M. Catai and Antônio G. Ferreira
Molecules 2022, 27(24), 8656; https://doi.org/10.3390/molecules27248656 - 7 Dec 2022
Cited by 7 | Viewed by 3468
Abstract
Aging process is characterized by a progressive decline of several organic, physiological, and metabolic functions whose precise mechanism remains unclear. Metabolomics allows the identification of several metabolites and may contribute to clarifying the aging-regulated metabolic pathways. We aimed to investigate aging-related serum metabolic [...] Read more.
Aging process is characterized by a progressive decline of several organic, physiological, and metabolic functions whose precise mechanism remains unclear. Metabolomics allows the identification of several metabolites and may contribute to clarifying the aging-regulated metabolic pathways. We aimed to investigate aging-related serum metabolic changes using a metabolomics approach. Fasting blood serum samples from 138 apparently healthy individuals (20–70 years old, 56% men) were analyzed by Proton Nuclear Magnetic Resonance spectroscopy (1H NMR) and Liquid Chromatography-High-Resolution Mass Spectrometry (LC-HRMS), and for clinical markers. Associations of the metabolic profile with age were explored via Correlations (r); Metabolite Set Enrichment Analysis; Multiple Linear Regression; and Aging Metabolism Breakpoint. The age increase was positively correlated (0.212 ≤ r ≤ 0.370, p < 0.05) with the clinical markers (total cholesterol, HDL, LDL, VLDL, triacylglyceride, and glucose levels); negatively correlated (−0.285 ≤ r ≤ −0.214, p < 0.05) with tryptophan, 3-hydroxyisobutyrate, asparagine, isoleucine, leucine, and valine levels, but positively (0.237 ≤ r ≤ 0.269, p < 0.05) with aspartate and ornithine levels. These metabolites resulted in three enriched pathways: valine, leucine, and isoleucine degradation, urea cycle, and ammonia recycling. Additionally, serum metabolic levels of 3-hydroxyisobutyrate, isoleucine, aspartate, and ornithine explained 27.3% of the age variation, with the aging metabolism breakpoint occurring after the third decade of life. These results indicate that the aging process is potentially associated with reduced serum branched-chain amino acid levels (especially after the third decade of life) and progressively increased levels of serum metabolites indicative of the urea cycle. Full article
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