Gaborieau Marianne, Matz Markus, Tratz Johanna, Pollard Michael, Wilhelm Manfred
Institute of Chemical Technology and Polymer Chemistry, Karlsruhe Institute of Technology (KIT), Engesserstraße 18, 76131, Karlsruhe, Germany.
Macromol Rapid Commun. 2025 May 18:e2500239. doi: 10.1002/marc.202500239.
HPLC is coupled online for the first time to 2D-NMR on a benchtop NMR spectrometer. The potential is demonstrated at 80 MHz with COSY (H-H COrrelation SpectroscopY) for a mixture of methyl and propyl parabens, additives commonly used in cosmetics. To lessen the impact of short residence time in the NMR flow cell, a repetition delay reduction combined with non-uniform sampling (NUS) allows decreasing the COSY experiment duration from 1 h to 2 min. The HPLC-benchtop 2D-NMR online coupling is established for the first time, using three different modes: stop-flow (with short stops at the analyte peaks and in the baseline), slow-flow (with a lower, constant flow rate over the whole elution range of analytes) and steady-flow (with a constant flow rate throughout the experiment). The HPLC-benchtop 2D-NMR online coupling allows the successful separation and characterization of methyl and propyl parabens at low field. This provides more in-depth chemical information on separated analytes than HPLC-benchtop 1D-NMR, with a smaller footprint, reduced experimental complexity and at lower costs than HPLC-high-field 2D-NMR. It opens the way to other 2D-NMR experiments and the characterization of a wider range of analytes such as oligomers, small molar mass additives, or polymers.
高效液相色谱（HPLC）首次与台式核磁共振光谱仪上的二维核磁共振（2D-NMR）在线联用。在80兆赫兹频率下，利用COSY（氢-氢相关光谱）对化妆品中常用添加剂对羟基苯甲酸甲酯和对羟基苯甲酸丙酯的混合物进行了演示。为了减少在核磁共振流通池中的短停留时间的影响，采用重复延迟减少结合非均匀采样（NUS）的方法，可将COSY实验时长从1小时缩短至2分钟。首次建立了HPLC-台式2D-NMR在线联用，采用三种不同模式：停流（在分析物峰处和基线处短暂停留）、慢流（在分析物的整个洗脱范围内以较低的恒定流速）和稳流（在整个实验过程中保持恒定流速）。HPLC-台式2D-NMR在线联用能够在低场成功分离和表征对羟基苯甲酸甲酯和对羟基苯甲酸丙酯。与HPLC-台式一维核磁共振相比，这为分离出的分析物提供了更深入的化学信息，占用空间更小，实验复杂度降低，且成本低于HPLC-高场二维核磁共振。它为其他二维核磁共振实验以及更广泛的分析物（如低聚物、小摩尔质量添加剂或聚合物）的表征开辟了道路。
