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首页> 外文期刊>Environmental toxicology and chemistry >RAPID ESTIMATION OF NUCLEAR MAGNETIC RESONANCE EXPERIMENT TIME IN LOW-CONCENTRATION ENVIRONMENTAL SAMPLES
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RAPID ESTIMATION OF NUCLEAR MAGNETIC RESONANCE EXPERIMENT TIME IN LOW-CONCENTRATION ENVIRONMENTAL SAMPLES

机译：低浓度环境样品中核磁共振实验时间的快速估计

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摘要

Nuclear magnetic resonance (NMR) spectroscopy is an essential tool for studying environmental samples but is often hindered by low sensitivity, especially for the direct detection of nuclei such as~(13)C. In very heterogeneous samples with NMR nuclei at low abundance, such as soils, sediments, and air particulates, it can take days to acquire a conventional ~(13)C spectrum. The present study describes a prescreening method that permits the rapid prediction of experimental run time in natural samples. The approach focuses the NMR chemical shift dispersion into a single spike, and, even in samples with extremely low carbon content, the spike can be observed in two to three minutes, or less. The intensity of the spike is directly proportional to the total concentration of nuclei of interest in the sample. Consequently, the spike intensity can be used as a powerful prescreening method that answers two key questions: (1) Will this sample produce a conventional NMR spectrum? (2) How much instrument time is required to record a spectrum with a specific signal-to-noise (S/N) ratio? The approach identifies samples to avoid (or pretreat) and permits additional NMR experiments to be performed on samples producing high-quality NMR data. Applications in solid- and liquid-state ~(13)C NMR are demonstrated, and it is shown that the technique is applicable to a range of nuclei.
机译：核磁共振（NMR）光谱是研究环境样品的必不可少的工具，但通常由于灵敏度低而受到阻碍，特别是对于直接检测诸如〜（13）C之类的原子核。在具有低丰度NMR核的非均质样品中，例如土壤，沉积物和空气微粒中，可能需要几天的时间才能获得常规的〜（13）C光谱。本研究描述了一种预筛选方法，该方法可以快速预测天然样品中的实验运行时间。该方法将NMR化学位移分散集中在一个峰中，即使在碳含量极低的样品中，也可以在两到三分钟或更短时间内观察到峰。尖峰的强度与样品中目标核的总浓度成正比。因此，尖峰强度可用作回答两个关键问题的强大的预筛选方法：（1）该样品会产生常规的NMR谱吗？ （2）记录具有特定信噪比（S / N）的频谱需要多少仪器时间？该方法可识别要避免（或预处理）的样品，并允许对产生高质量NMR数据的样品进行其他NMR实验。证明了在固态和液态〜（13）C NMR中的应用，并且表明该技术适用于一系列核。

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