Magnetic Resonance in Chemistry最新文献

{"title":"Clean Selective Refocusing Sequences With Sensitivity and Resolution Enhancement-A Review.","authors":"Suryaprakash Nagaraja Rao","doi":"10.1002/mrc.5534","DOIUrl":"https://doi.org/10.1002/mrc.5534","url":null,"abstract":"<p><p>The selective refocusing (SERF) and its modified experiments have permitted the unambiguous assignment of peaks and the straightforward determination of ⁿJ_HH. However, they suffer from the presence of intense axial peaks and the evolution of undesirable couplings in the spectra. In partially addressing these challenges, the Clean-G-SERF sequence, a modified version of the gradient-enhanced SERF-based experiment (G-SERF), has been designed to suppress all the axial peaks and eradicate the unwanted evolution, while retaining only the couplings pertaining to the selectively excited proton. Furthermore, the incorporation of a perfect echo block provided the leverage for increasing slice thickness leading to the increased sensitivity. To additionally enhance the resolution in the direct dimension, the improved sequences have been designed by the incorporation of pure shift, where the homonuclear J couplings are refocused in real time. All these methods permitted the unambiguous assignment of peaks to the coupled partners of the selectively excited proton, thereby enabling the accurate measurement of couplings. The broader utility of the designed sequences, cited in the literature as Clean-G-SERF, Clean-PE-SERF, PS-Clean-G-SERF and PS-Clean-PE-SERF have been demonstrated on several chosen examples including the molecular mixtures for the accurate measurement of J_HH.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144143168","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantitative Solid-State NMR Spectroscopy (qSSNMR) in Pharmaceutical Analysis.","authors":"Zhaoxi Zheng, Kang Chen, Yang Liu, Eric J Munson, Yongchao Su","doi":"10.1002/mrc.5536","DOIUrl":"https://doi.org/10.1002/mrc.5536","url":null,"abstract":"<p><p>Pharmaceutical analysis is essential to drug development and quality assurance, ensuring that products meet stringent safety and efficacy standards. Quantitative solid-state NMR (qSSNMR) has become a key technique, enabling precise quantification and characterization of solid drug formulations. This mini-review highlights the evolution of qSSNMR, focusing on improvements in detection limits, resolution, and high-throughput capabilities. This review explores technical advancements and applications for analyzing complex pharmaceutical mixtures. While challenges remain for widespread adoption, efforts in automation, user-friendly software, and collaboration aim to address these.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144143169","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Position-Specific Substitution in Cellulose Ethers Studied by DNP Enhanced Solid-State NMR Spectroscopy.","authors":"Hampus Karlsson, Arthur C Pinon, Leif Karlson, Helena Wassenius, Frida Iselau, Staffan Schantz, Lars Evenäs","doi":"10.1002/mrc.5535","DOIUrl":"https://doi.org/10.1002/mrc.5535","url":null,"abstract":"<p><p>Ethyl hydroxyethyl cellulose (EHEC) and methyl ethyl hydroxyethyl cellulose (MEHEC) are hydrophilic cellulose ethers commonly employed as rheology modifiers in diverse industrial applications. The performance of these polymers, and their resistance to degradation by various cellulase enzymes, depends on their intricate molecular structure. Distribution of the etherifying groups, within the anhydroglucose units and along the polymer chain, is the key property to control. However, characterizing such structural properties is challenging, necessitating the development of novel analysis methods. In this study, we demonstrate the application of solid-state nuclear magnetic resonance (NMR) spectroscopy, enhanced by dynamic nuclear polarization (DNP), for this purpose. We prove that the hydrophilic EHEC and MEHEC samples are homogenously swelled in D₂O/H₂O-based radical solutions, a necessity to ensure uniform DNP enhancement throughout the material. And we illustrate how the high sensitivity enhancements obtained can be used to perform selective, J-coupling-based C1 to C2 transfer experiments to measure the fraction of substituted C2 positions in these cellulose ethers. Moreover, with further refinement, the methodology outlined in this work holds promise for elucidating C3-specific substitution patterns.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144128095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"From Percent to Permil: Requirements to Increase Accuracy of Quantitative NMR Measurements.","authors":"Margot Sanchez, Serge Akoka","doi":"10.1002/mrc.5531","DOIUrl":"https://doi.org/10.1002/mrc.5531","url":null,"abstract":"<p><p>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.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144120093","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Collaborative Study on Platform ¹H Quantitative NMR Method Using Internal Calibration Methodology: Towards Capacity Building for Novices.","authors":"Baoning Su, Jing Zhang, Xiaojuan Deng, Huiwen Deng, Songzi Jiang, Hui Fu, Jian Wang, Alan Wei, Qingwen Zhang, Jie Liu, Sunil Babu Paudel, Taijun Hang, Xiaofei Lu, Wei Zhang, Guosheng Ding, Li Gan, Xianzhong Yan, Yang Liu, Caiyu Zhang, Yang Liu","doi":"10.1002/mrc.5532","DOIUrl":"https://doi.org/10.1002/mrc.5532","url":null,"abstract":"<p><p>Over the past 20 years, the use of quantitative nuclear magnetic resonance (qNMR) technology has grown significantly in pharmaceutical industry. However, its broader adoption is often limited by specialized expertise required to implement best practices. Recent discussions within the qNMR community in China (qNMR-C) have highlighted the benefits of establishing an applicable qNMR platform method-one that serves as a universal approach, adaptable across multiple products. This approach aims to standardize a single set of qNMR parameters to address the majority of quantitative applications and making qNMR more accessible, particularly for researchers new to the field. The present study outlines the rationale behind the proposed qNMR platform method and demonstrates its strategic framework through a series of designed tests. Key parameters influencing qNMR accuracy and precision, including signal-to-noise ratio, data processing, integration approaches, relaxation delays, T₁ relaxation times, and sample weight, were systematically evaluated. A collaborative effort involving 12 NMR instruments across eight laboratories assessed the method's applicability and demonstrated its proper design space. Another objective of this study is to streamline the qNMR workflow, enabling novices to produce reliable, high-quality data early in their learning while ensuring reproducible and meaningful results. Furthermore, this work calls upon the global qNMR community to engage in the continued validation of the proposed platform method, fostering collective knowledge and verifying its robustness across diverse applications.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-05-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144120022","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Micellar Solubilization of Phenols With One or Two Hydroxyl Groups Using Biological Surfactant Rhamnolipid","authors":"Victor P. Arkhipov,&nbsp;Ruslan V. Arkhipov,&nbsp;Andrei Filippov","doi":"10.1002/mrc.5530","DOIUrl":"10.1002/mrc.5530","url":null,"abstract":"<p>We studied the solubilization of phenols with one and two hydroxyl groups (phenol, p-cresol, guaiacol, and pyrocatechol, resorcinol, hydroquinone) by micelles of the biological surfactant rhamnolipid using NMR diffusometry. We discuss the results within the framework of a model of two states of solubilizer molecules in solution: free in the aqueous phase and bound in surfactant micelles. The solubilization characteristics of rhamnolipid were calculated: the proportion of solubilized molecules р, micelle-water partition coefficient <i>K</i>_<i>m</i>, and molar solubilization ratio (MSR) depending on the concentration of rhamnolipid in solutions.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"63 7","pages":"508-517"},"PeriodicalIF":1.9,"publicationDate":"2025-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.5530","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144094303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Sensitivity of Projections of Backbone ¹³C^α/¹⁵N Chemical Shielding Along Covalent Bonds to Protein Secondary Structure-An Ab Initio Study.","authors":"Shaniya Sunny, Sivakumar Paramasivam","doi":"10.1002/mrc.5533","DOIUrl":"https://doi.org/10.1002/mrc.5533","url":null,"abstract":"<p><p>Statistical analysis of backbone ¹³C^α and ¹⁵N chemical shielding tensors (CST) computed using the DFT-GIAO method is presented for 40 alanine residues located centrally in three-residue segments extracted from α-helical and β-sheet regions of 12 proteins with high-resolution crystal structures. Our results show that the projections of ¹³C^α shielding along the three covalent bond directions, C^α-C^β, C^α-H^α, and C^α-N, exhibit significantly higher sensitivity to secondary structure than the principal components. The increased sensitivity is due to the changes in the orientation of ¹³C^α CST in the molecular frame of the two secondary structures. Similarly, the projections of backbone amide ¹⁵N shielding along the covalent bonds N-H, N-C^α and along the normal direction to the peptide plane have a reasonably higher sensitivity to the secondary structure than the principal components. Unlike ¹³C^α nuclei, the orientation of amide ¹⁵N CST in the molecular frame is found to be invariant in the two secondary structures. The calculated amide ¹⁵N chemical shielding anisotropies (CSA) are larger in helix than in sheet structure, consistent with the experimental ¹⁵N chemical shift studies reported in the literature. Furthermore, two-dimensional correlation plots of backbone ¹³C^α and ¹⁵N CSA parameters show a clear distinction between the two major secondary structure elements.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":" ","pages":""},"PeriodicalIF":1.9,"publicationDate":"2025-05-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144102205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Non-Uniform Sampling for Quantitative NOESY","authors":"William T. P. Darling,&nbsp;Sven G. Hyberts,&nbsp;Mate Erdelyi","doi":"10.1002/mrc.5529","DOIUrl":"10.1002/mrc.5529","url":null,"abstract":"<p>Non-uniform sampling (NUS) enables faster acquisition of NMR spectra. Concerns about spectral fidelity, particularly in high-dynamic-range experiments like NOESY, have limited its quantitative applications. In this study, we assessed whether optimised Poisson-gap sampling schemes can generate high-fidelity spectra suitable for quantitation and evaluated the effectiveness of NUS ranking tools, NUSscore and nus-tool, in identifying optimal sampling schemes. A total of 25,000 Poisson-gap sampling schemes were generated and ranked using NUSscore, with a subset of 11 of these spanning the score distribution, alongside 15 random-shuffle and the highest and lowest scoring Poisson-gap schemes determined using the signal apex-to-artefact ratio were used for comparison, all with 50% sampling coverage. Additionally, hybrid sampling schemes incorporating a long initial uniformly sampled section, termed US-NUS hybrid schemes, were evaluated. Spectral fidelity was evaluated on interproton distance accuracy, including the proportion of retained interproton distances and their deviation from uniformly sampled reference spectra. NUSscore showed a strong correlation with spectral fidelity. The peak-to-sidelobe ratio implemented in nus-tool showed no correlation, with the relative sensitivity metric showing a weak correlation. Signal-to-artefact apex ratio was also not predictive for identifying sampling schedules with maintained interproton distances. All Poisson-gap sampling schemes however outperformed random-shuffle. The US-NUS hybrids demonstrated improved interproton distance conservation than traditional Poisson-gap sampling schemes with a low seed dependence, making them a promising sampling schedule for quantitative NOESY analysis.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"63 7","pages":"495-507"},"PeriodicalIF":1.9,"publicationDate":"2025-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.5529","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144078783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Aqueous Carbonation of Calcium Silicates With Different Ca/Si Ratios Studied by Solid-State NMR Spectroscopy","authors":"Rune Wittendorff Mønster Jensen,&nbsp;Jørgen Skibsted","doi":"10.1002/mrc.5528","DOIUrl":"10.1002/mrc.5528","url":null,"abstract":"<p>Calcium silicates react readily with CO₂ under aqueous conditions, forming CaCO₃ and silica gel. This is utilized to produce new cement binders and to sequester CO₂, thereby contributing to a lowering of the CO₂ footprint for the cement industry. The present work investigates aqueous carbonation of three hydraulic and three non-hydraulic calcium silicates with the aim of analyzing the impact of the Ca/Si ratio on the structure of the amorphous silica gel and on the extent and rate of carbonation. This information is obtained from ²⁹Si NMR experiments, whereas ¹³C NMR and FT-IR are used to characterize the polymorphic forms of CaCO₃ formed upon carbonation. The structure of the silica gel is not dependent on the type of carbonated calcium silicate or their Ca/Si ratio. In addition, the amounts of CaCO₃ from TGA analysis match well the theoretical maximum values. ²⁹Si and ²⁹Si{¹H} CP/MAS spectra of a commercial silica gel are very similar to those observed for the carbonated calcium silicates, which strongly suggests that a hydroxylated silica gel without incorporated Ca ions constitutes the silica gel in carbonated calcium silicates. From ¹³C NMR and FT-IR, it is found that calcite is the principal CaCO₃ polymorph for all samples carbonated for 6 h. However, aragonite and calcite do co-exist during the initial carbonation (20 min) of γ-Ca₂SiO₄. Comparison of the carbonation evolution for the hydraulic and non-hydraulic calcium silicates strongly suggests that an early hydration and formation of C-S-H is not a required initial step in the aqueous carbonation process.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"63 7","pages":"476-494"},"PeriodicalIF":1.9,"publicationDate":"2025-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.5528","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144078775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"NMR as a Discovery Tool: Exploration of Industrial Effluents Discharged Into the Environment","authors":"Kiera Ronda,&nbsp;Jeremy Gauthier,&nbsp;Khanisha Singaravadivel,&nbsp;Peter M. Costa,&nbsp;Katelyn Downey,&nbsp;William W. Wolff,&nbsp;Daniel H. Lysak,&nbsp;Jacob Pellizzari,&nbsp;Owen Vander Meulen,&nbsp;Katrina Steiner,&nbsp;Amy Jenne,&nbsp;Monica Bastawrous,&nbsp;Zainab Ng,&nbsp;Agnes Haber,&nbsp;Benjamin Goerling,&nbsp;Venita Busse,&nbsp;Falko Busse,&nbsp;Colin Elliot,&nbsp;Scott Mabury,&nbsp;Mohamed Ateia,&nbsp;Derek C. G. Muir,&nbsp;Robert J. Letcher,&nbsp;Krish Krishnamurthy,&nbsp;Sonya Kleywegt,&nbsp;Karl J. Jobst,&nbsp;Myrna J. Simpson,&nbsp;Andre J. Simpson","doi":"10.1002/mrc.5527","DOIUrl":"10.1002/mrc.5527","url":null,"abstract":"<p>NMR provides unprecedented molecular information, urgently needed by environmental researchers and policy makers. However, NMR is underutilized in environmental sciences due to the lack of available technologies, limited environmental-specific training opportunities, and easy-to-use workflows. NMR has considerable potential as a discovery tool for novel pollutants, and by-products, exemplified by the recent discovery of the degradation by-product of a rubber additive, 6PPD-quinone, now considered one of the most toxic compounds presently known. This work represents a proof-of-concept case study highlighting the use of NMR to profile effluents from 38 industries across Ontario, Canada. Wastewater effluents from various industrial sectors were analyzed using several 1D and 2D ¹H/¹³C NMR and ¹⁹F experiments and were screened both unconcentrated and after lyophilization. Common species could be identified using human metabolic NMR databases, but environmental-specific NMR databases desperately need further development. An example of manually identifying unusual NMR signatures is included; these resulted from phosphinic and phosphonic acids originating from the electroplating industry, for which the environmental impacts are not well understood. Basic ¹H NMR quantification is performed using ERETIC, while an optimized approach combining relaxation agents and steady-state-free-precession ¹⁹F NMR, to reduce detection limits (at 500 MHz) to sub-ppb (&lt; 1 μg/L) in under 15 min, is demonstrated. The future potential of benchtop NMR (80 MHz) is also considered. This paper represents a guide to others interested in applying NMR spectroscopy to environmental media and demonstrates the potential of NMR as a complementary tool to assist MS in environmental pollutant and by-product discovery.</p>","PeriodicalId":18142,"journal":{"name":"Magnetic Resonance in Chemistry","volume":"63 7","pages":"453-475"},"PeriodicalIF":1.9,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mrc.5527","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143989517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}