VERIFIN, University of Helsinki, Helsinki, Finland.
J Magn Reson. 2010 Jan;202(1):24-33. doi: 10.1016/j.jmr.2009.09.021. Epub 2009 Sep 30.
The finite RF power available on carbon channel in proton-carbon correlation experiments leads to non-uniform cross peak intensity response across carbon chemical shift range. Several classes of broadband pulses are available that alleviate this problem. Adiabatic pulses provide an excellent magnetization inversion over a large bandwidth, and very recently, novel phase-modulated pulses have been proposed that perform 90 degrees and 180 degrees magnetization rotations with good offset tolerance. Here, we present a study how these broadband pulses (adiabatic and phase-modulated) can improve quantitative application of the heteronuclear single quantum coherence (HSQC) experiment on high magnetic field strength NMR spectrometers. Theoretical and experimental examinations of the quantitative, offset-compensated, CPMG-adjusted HSQC (Q-OCCAHSQC) experiment are presented. The proposed experiment offers a formidable improvement to the offset performance; (13)C offset-dependent standard deviation of the peak intensity was below 6% in range of+/-20 kHz. This covers the carbon chemical shift range of 150 ppm, which contains the protonated carbons excluding the aldehydes, for 22.3 T NMR magnets. A demonstration of the quantitative analysis of a fasting blood plasma sample obtained from a healthy volunteer is given.
在质子-碳相关实验中，碳通道上可用的有限射频功率导致碳化学位移范围内的交叉峰强度响应不均匀。有几类宽带脉冲可用于缓解此问题。绝热脉冲在较大带宽上提供了极好的磁化反转，并且最近提出了新型的相位调制脉冲，这些脉冲具有良好的偏移容限，可实现 90 度和 180 度的磁化旋转。在这里，我们研究了这些宽带脉冲（绝热和相位调制）如何可以改善在高强度磁场 NMR 光谱仪上进行异核单量子相干（HSQC）实验的定量应用。提出了对定量、偏移补偿、CPMG 调整的 HSQC（Q-OCCAHSQC）实验进行理论和实验检验。所提出的实验对偏移性能有很大的改进；在+/-20 kHz 的范围内，峰强度的（13）C 偏移相关标准偏差低于 6％。这涵盖了质子化碳的碳化学位移范围，不包括醛，对于 22.3 T NMR 磁铁。给出了从健康志愿者获得的禁食血浆样本的定量分析示例。
