Faculty of Chemistry, Biological and Chemical Research Centre, University of Warsaw, Żwirki i Wigury 101, 02-089 Warsaw, Poland; Centre of New Technologies, University of Warsaw, Banacha 2C, 02-097 Warsaw, Poland.
Centre of New Technologies, University of Warsaw, Banacha 2C, 02-097 Warsaw, Poland.
J Magn Reson. 2018 Sep;294:1-6. doi: 10.1016/j.jmr.2018.06.009. Epub 2018 Jun 19.
Nuclear magnetic resonance (NMR) spectroscopy is frequently applied in quantitative chemical analysis (qNMR). It is easy to measure one-dimensional (1D) NMR spectra in a quantitative regime (with appropriately long relaxation delays and acquisition times); however, their applicability is limited in the case of complex samples with severe peak overlap. Two-dimensional (2D) NMR solves the overlap problem, but at the cost of biasing peak intensities and hence quantitativeness. This is partly due to the uneven coherence transfer between excited/detected H nuclei and the heteronuclei coupled to them (typically C). In the traditional approach, the transfer occurs via the evolution of a spin system state under the J-coupling Hamiltonian during a delay of a fixed length. The delay length is set on the basis of the predicted average coupling constant in the sample. This leads to disturbances for pairs of nuclei with coupling constants deviating from this average. Here, we present a novel approach based on non-standard processing of the data acquired in experiments, where the coherence transfer delay is co-incremented with non-uniformly sampled evolution time. This method allows us to obtain the optimal transfer for all resonances, which improves quantitativeness. We demonstrate the concept for the coherence transfer and multiplicity-edit delays in a heteronuclear single-quantum correlation experiment (HSQC).
核磁共振（NMR）光谱经常应用于定量化学分析（qNMR）。在定量条件下（采用适当长的弛豫延迟和采集时间），很容易测量一维（1D）NMR 谱；然而，对于具有严重峰重叠的复杂样品，其适用性有限。二维（2D）NMR 解决了重叠问题，但代价是峰强度出现偏差，从而影响定量性。这部分是由于激发/检测 H 核与与其偶合的异核（通常为 C）之间的不均匀相干转移。在传统方法中，相干转移通过在固定长度的延迟期间在 J 偶合哈密顿量下的自旋系统状态演化来进行。延迟长度基于样品中预测的平均偶合常数来设置。这会导致与平均偶合常数偏离的核对产生干扰。在这里，我们提出了一种基于对实验中获取的数据进行非标准处理的新方法，其中相干转移延迟与非均匀采样演化时间共同增加。该方法允许我们为所有共振获得最佳转移，从而提高定量性。我们在异核单量子相关实验（HSQC）中演示了相干转移和多重编辑延迟的概念。
