Suppression of Protonated Organic Solvents in NMR Spectroscopy Using a Perfect Echo Low-Pass Filtration Pulse Sequence,Analytical Chemistry

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Suppression of Protonated Organic Solvents in NMR Spectroscopy Using a Perfect Echo Low-Pass Filtration Pulse Sequence
Analytical Chemistry ( IF 6.7 ) Pub Date : 2018-03-19 00:00:00 , DOI: 10.1021/acs.analchem.8b00621
Peter W. A. Howe ₁

Affiliation

Proton NMR spectra are usually acquired using deuterated solvents, but in many cases it is necessary to obtain spectra on samples in protonated solvents. In these cases, the intense resonances of the protonated solvents need to be suppressed to maximize sensitivity and spectral quality. A wide range of highly effective solvent suppression methods have been developed, but additional measures are needed to suppress the ¹³C satellites of the solvent. Because the satellites represent 1.1% of the original solvent signal, they remain problematic if unsuppressed. The recently proposed DISPEL pulse sequences suppress ¹³C satellites extremely effectively, and this Technical Note demonstrates that combining DISPEL and presaturation results in exceptionally effective solvent suppression. An important element in the effectiveness is volume selection, which is inherent within the DISPEL sequence. Spectra acquired in protonated dimethlysulfoxide and tetrahydrofuran show that optimum results are obtained by modifying the phase cycle, cycling the pulse-field gradients, and using broadband ¹³C inversion pulses to reduce the effects of radiofrequency offset and inhomogeneity.

中文翻译：

使用完美回波低通滤波脉冲序列在NMR光谱中抑制质子化有机溶剂

质子核磁共振谱图通常是使用氘代溶剂获得的，但在许多情况下，有必要在质子化溶剂中获得样品的质谱图。在这些情况下，需要抑制质子化溶剂的强烈共振，以最大程度地提高灵敏度和光谱质量。已经开发了多种高效的溶剂抑制方法，但是还需要采取其他措施来抑制¹³ C卫星溶剂。因为卫星代表原始溶剂信号的1.1％，所以如果不加抑制，它们仍然是有问题的。最近提出的DISPEL脉冲序列抑制了¹³C卫星极为有效，并且本技术说明证明，将DISPEL和预饱和结合使用会产生异常有效的溶剂抑制作用。有效性的一个重要因素是音量选择，这是DISPEL序列中固有的。在质子化的二甲基亚砜和四氢呋喃中获得的光谱表明，通过修改相位周期，循环脉冲场梯度以及使用宽带¹³ C反转脉冲来减少射频偏移和不均匀性的影响，可以获得最佳结果。

更新日期：2018-03-19

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