Resolved-GSERF: A Proficient NMR Approach for Identifying Accurate J-Coupling Constants of Targeted Peaks from...

SElective ReFocusing (SERF)-based experiments present an effective tool for discerning proton-proton J-coupling constants of targeted spectral peaks. Nevertheless, the performance of SERF experiments highly relies on the selective excitation of isolated signals. The extraction of targeted peaks from spectral congestion, even from spectral overlap, generally poses a challenge to SERF-based experiments for accurate analysis of associated coupling constants due to the existence of redundant axial peaks and unwanted couplings. Herein, we propose an NMR method called resolved-GSERF to address this challenge and achieve accurate J-coupling measurements on targeted spectral peaks. In this approach, the selective magnetization transfer scheme with an appropriate spin-lock mixing time is employed to isolate the targeted peak signal from the spectral congestion region, thereby enhancing spectral sensitivity and resolution. The slice-selection-based GSERF refocusing encoding scheme is subsequently applied to extract J-coupling constant information of the targeted peak. The experimental results on complex chemical and biomedical samples suggest that the proposed approach offers a practical solution to the challenge of spectral congestion for identifying accurate J-couplings.