In phase selective excitation of overlapping multiplets by gradient-enhanced chemical shift selective filters
In phase selective excitation of overlapping multiplets by gradient-enhanced chemical shift selective filters
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DOI：
10.1016/j.jmr.2004.06.004
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发表时间：
2004-09-01
影响因子：
2.2
通讯作者：
Uhrín, D
中科院分区：
文献类型：
--
作者：
Robinson, PT;Pham, TN;Uhrín, D
我们研制了用于重叠多重态H-1同相激发的梯度增强化学位移选择滤光片(GE-CSSF)。这种方法依赖于开共振信号的建设性相加，而非共振磁化则通过可变化学位移演化的相消干涉来消除。这是通过将通过逐渐增加的化学位移演化期获得的几个FID共同添加来实现的。提出了两个可变时间和一个恒定时间的GE-CSSF，它可以与TOCSY、NOESY和ROESY混合格式相结合，产生高选择性的一维实验。给出了计算Ge-CSSF的激发轮廓和考察自旋-自旋弛豫、CSSF增量长度和选择性反转脉冲影响的解析和数值表达式。我们从理论和实验上证明了CSSF对具有小到1-2赫兹的自旋-自旋弛豫时间和化学位移差的化合物产生了快速的信号分离。脉冲场梯度的使用确保获得非常干净的光谱。这些技术的主要应用在于混合物的分析，其中严重的光谱重叠阻碍了简单的一维选择方法的使用。(C)2004 Elsevier Inc.保留所有权利。
We have developed gradient-enhanced chemical shift selective filters (ge-CSSF) for inphase excitation of overlapping multiplets H-1. This method relies on the constructive addition of on resonance signal while off resonance magnetization is eliminated by destructive interference due to variable chemical shift evolution. This is achieved by co-addition of several FIDs acquired with a gradually incremented chemical shift evolution period. Two variable-time and one constant-time ge-CSSFs are proposed that can be combined with TOCSY, NOESY, and ROESY mixing schemes yielding highly selective 1D experiments. Analytical and numerical expressions are derived to calculate the excitation profiles of the ge-CSSFs and to examine the effects of spin-spin relaxation, the length of the CSSF increment, and selective inversion pulses. We demonstrate, both theoretically and experimentally, that CSSFs yield fast signal separation for compounds with a range of spin-spin relaxation times and chemical shift differences as small as 1-2 Hz. The use of pulsed field gradients ensures that very clean spectra are obtained. The main application of these techniques lies in analysis of mixtures where severe spectral overlap prevents the use of simple 1D selective methods. (C) 2004 Elsevier Inc. All rights reserved.