Novel coupled methods in high performance liquid chromatography with 1D/2D NMR detection based on low field NMR spectrometer

该项目的目的是开发基于高效液相色谱（HPLC）与化学选择性核磁共振检测联用的耦合分析方法。基于永磁体的紧凑型低场光谱仪用作化学选择性检测，并针对与HPLC的在线耦合进行了优化。目标是分离分析物混合物，同时通过光谱法对其进行表征，从而实现以前无法实现的详细表征。该项目正在采取几种方法来优化方法，最重要的方面是溶剂抑制，调整二维核磁共振方法与色谱法联用，以及使用新的色谱法，傅立叶液相色谱法（FT-LC）提高方法的灵敏度。抑制溶剂信号，特别是有计划地使用质子化溶剂，是普遍适用的表征方法的最基本方法之一。质子化溶剂的强烈信号，通常是分析物峰的1000倍以上，将通过不同溶剂抑制方法的新组合来消除，从而优化灵敏度和选择性。溶剂抑制的一个重要方面是溶剂梯度的优化，溶剂梯度用于HPLC中的样品分离，由于各种效应，NMR信号的化学位移的漂移。该项目的第二个重要方法是使用2D NMR检测与HPLC耦合。通过添加额外的光谱维度，可以获得关于分析物的更详细的分子信息，例如通过2D DOSY实验确定分子大小。一个目标是最小化更复杂的2D NMR实验的测量时间，因为光谱分析所需的测量时间限制了联用分析中色谱分离的分辨率。对于所需的测量时间来说，方法的灵敏度也很重要。在这里，计划项目的第三个方面是：通过应用一种新的色谱方法，也称为傅立叶变换液相色谱法（FT-LC），显着提高了方法的灵敏度。FT-LC是在尺寸排阻色谱法（SEC）中开发的，在本项目中将在液体吸附色谱法（LAC）中建立，用于分析小分子。整个项目的目的是开发一种hypenated表征方法，即使是复杂的分子混合物也可以进行完整的分析，但在获取和应用方面只需要合理的努力，这对于小型实验室来说也很有趣。这开辟了许多应用领域，例如聚合物、食品和药物分析。

The aim of the project is the development of coupled analytical methods based on high performance liquid chromatography (HPLC) hyphenated with chemically selective NMR detection. Compact low-field spectrometers based on permanent magnets are used as chemically selective detection and optimized for online coupling with HPLC. The goal is to separate analyte mixtures, characterize them simultaneously by spectroscopy, and thus enable detailed characterization that was previously unattainable. The project is pursuing several approaches to optimize the methodology, the most important aspects being solvent suppression, adaptation of 2D NMR methods for hyphenating with chromatography, and increasing the sensitivity of the methodology using a novel chromatographic method, Fourier liquid chromatography (FT-LC). The suppression of solvent signals, especially with the planned use of protonated solvents, is one of the most essential approaches for a universally applicable characterization method. The intense signals of protonated solvents, which are often a factor of 1000 above the peaks of the analytes, will be eliminated by a novel combination of different solvent suppression methods, thus optimizing sensitivity and selectivity. An important aspect of solvent suppression is the optimization for solvent gradients, which are used in HPLC for sample separation and make suppression difficult due to various effects, e.g., the drift of the chemical shift of the NMR signals. The second important approach of the project is the use of 2D NMR detection in coupling with HPLC. By adding an additional spectral dimension, much more detailed molecular information about the analytes is accessible, an example being molecular size determination via 2D DOSY experiments. One goal is to minimize the measurement time of the much more sophisticated 2D NMR experiments, since the required measurement time of spectroscopic analysis limits the resolution of chromatographic separation in the hyphenated analysis. Also of high importance for the required measurement time is the sensitivity of the methodology. Here the third aspect of the planned project comes in: The sensitivity of the methodology is to be significantly improved by the application of a new chromatographic method, also called Fourier Transformation Liquid Chromatography (FT-LC). The FT-LC was developed in size exclusion chromatography (SEC) and will in this project be established in liquid adsorption chromatography (LAC), for the analysis of small molecules. The aim of whole the project is to develop a hypenated characterization methodology that enables complete analysis of even complex mixtures of molecules and yet requires only resonable effort both in terms of acquisition and application, making it interesting for smaller laboratories as well. This opens up numerous fields of application, e.g. polymer, food and drug analysis.