基于选择性激发的核磁共振弛豫时间测量方法

IF 5.7 2区化学 Q1 CHEMISTRY, ANALYTICAL

Analytica Chimica Acta Pub Date : 2024-11-22 DOI:10.1016/j.aca.2024.343465

Xiaoqi Shi, Wen Zhu, Qing Zeng, Yao Luo, Zhong Chen, Yanqin Lin

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引用次数: 0

摘要

背景在核磁共振光谱学中，弛豫时间为了解分子结构、相互作用和动力学提供了宝贵的信息。然而，传统的弛豫时间测量技术会在光谱峰重叠时产生不准确的弛豫时间，原因是化学位移范围窄和 J 耦合分裂。虽然纯移位方法的组合可以解决这一问题，但由于其固有的缺点，如灵敏度低、采集时间长等，并未得到广泛应用。因此，亟需一种可行且灵敏的方法来测量重叠峰的弛豫时间。(87)结果本研究提出了一种将选择性激发与传统弛豫时间测量方法相结合的新方法，命名为 GEM-IR/CPMG，用于精确测量具有重叠峰的样品的纵向和横向弛豫时间。该方法的采集时间与传统方法相似，灵敏度损失较小。通过使用三种样品进行实验，证明了该方法的可行性和有效性：1-溴丁烷、丁醇和丁酸的混合物以及 17β-雌二醇。结果表明，该方法测得的弛豫时间与传统方法的结果基本一致。此外，为了证明该方法在低浓度样品中的优势，还测量了 8 mM 的雌二醇样品，结果与高浓度样品一致。(125)意义GEM-IR/CPMG 方法消除了质子弛豫时间测量中重叠峰的干扰，保留了样品的关键耦合信息，从而实现了弛豫时间的精确测量。此外，它还能在一次扫描中选择性地激发感兴趣的自旋，光谱灵敏度损失小，便于测量低浓度样品，因此广泛适用于化学分析。(62)

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Selective-excitation-based method for measurement of NMR relaxation time

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Selective-excitation-based method for measurement of NMR relaxation time

Background

Relaxation time provides invaluable insights into the molecular structure, interactions, and dynamics in nuclear magnetic resonance spectroscopy. However, conventional relaxation-time measurement techniques produce inaccurate relaxation times when the spectral peaks overlap because of the narrow chemical-shift range and J-coupled splitting. While the combination of pure-shift methods can solve this issue, they are not widely used due to their inherent drawbacks such as low sensitivity and long acquisition time. There is a great need for a feasible and sensitive method to measure the relaxation time for overlapping peaks. (87)

Results

This study proposes a new method that combines selective excitation with a conventional relaxation-time measurement method, named GEM-IR/CPMG, to accurately measure the longitudinal and transverse relaxation times in the samples with overlapping peaks. The method has a similar acquisition time as the conventional method with small sensitivity loss. The feasibility and effectiveness of the method were demonstrated through experiments using three types of samples: 1-bromobutane, a mixture of butanol and butyric acid, and 17β-estradiol. The results show that the relaxation times measured by this method are in general agreement with the results of the conventional method. In addition, to demonstrate the advantages of the method for low-concentration samples, a sample of estradiol at 8 mM was measured with the results obtained matching the high concentration. (125)

Significance

The GEM-IR/CPMG method eliminates interference from overlapping peaks in proton relaxation-time measurement and preserves the crucial coupling information of the sample, thus allowing accurate measurement of the relaxation time. Moreover, it selectively excites the spin of interest in a single scan, demonstrating a minor loss of spectral sensitivity and facilitating the measurement of low-concentration samples, making it widely applicable to chemical analyses. (62)

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来源期刊

Analytica Chimica Acta 化学-分析化学

CiteScore

10.40

自引率

6.50%

发文量

1081

审稿时长

38 days

期刊介绍： Analytica Chimica Acta has an open access mirror journal Analytica Chimica Acta: X, sharing the same aims and scope, editorial team, submission system and rigorous peer review. Analytica Chimica Acta provides a forum for the rapid publication of original research, and critical, comprehensive reviews dealing with all aspects of fundamental and applied modern analytical chemistry. The journal welcomes the submission of research papers which report studies concerning the development of new and significant analytical methodologies. In determining the suitability of submitted articles for publication, particular scrutiny will be placed on the degree of novelty and impact of the research and the extent to which it adds to the existing body of knowledge in analytical chemistry.