Silva Terra Ana I, Rossetto Matheus, Dickson Claire L, Peat George, Uhrín Dušan, Halse Meghan E
Department of Chemistry, University of York, YorkYO10 5DD, U.K.
EaStCHEM School of Chemistry, University of Edinburgh, EdinburghEH9 3FJ, U.K.
ACS Meas Sci Au. 2022 Nov 8;3(1):73-81. doi: 10.1021/acsmeasuresciau.2c00055. eCollection 2023 Feb 15.
Benchtop NMR spectrometers provide a promising alternative to high-field NMR for applications that are limited by instrument size and/or cost. F benchtop NMR is attractive due to the larger chemical shift range of F relative to H and the lack of background signal in most applications. However, practical applications of benchtop F NMR are limited by its low sensitivity due to the relatively weak field strengths of benchtop NMR spectrometers. Here we present a sensitivity-enhancement strategy that combines SABRE (Signal Amplification By Reversible Exchange) hyperpolarization with the multiplet refocusing method SHARPER (Sensitive, Homogeneous, And Resolved PEaks in Real time). When applied to a range of fluoropyridines, SABRE-SHARPER achieves overall signal enhancements of up to 5700-fold through the combined effects of hyperpolarization and line-narrowing. This approach can be generalized to the analysis of mixtures through the use of a selective variant of the SHARPER sequence, SHARPER. The ability of SABRE-SHARPER to simultaneously boost sensitivity and discriminate between two components of a mixture is demonstrated, where selectivity is achieved through a combination of selective excitation and the choice of polarization transfer field during the SABRE step.
对于受仪器尺寸和/或成本限制的应用而言，台式核磁共振波谱仪为高场核磁共振提供了一种很有前景的替代方案。由于氟相对于氢具有更大的化学位移范围，且在大多数应用中没有背景信号，因此台式氟核磁共振很有吸引力。然而，由于台式核磁共振波谱仪的场强相对较弱，其低灵敏度限制了台式氟核磁共振的实际应用。在此，我们提出一种灵敏度增强策略，该策略将SABRE（通过可逆交换进行信号放大）超极化与多重峰重聚焦方法SHARPER（实时灵敏、均匀且分辨的峰）相结合。当应用于一系列氟吡啶时，SABRE-SHARPER通过超极化和线宽变窄的综合作用，实现了高达5700倍的整体信号增强。通过使用SHARPER序列的选择性变体SHARPER，这种方法可以推广到混合物分析。展示了SABRE-SHARPER同时提高灵敏度和区分混合物中两种成分的能力，其中选择性是通过选择性激发和SABRE步骤中极化转移场的选择相结合来实现的。
