基于纵向多自旋阶与Hadamard编码拥挤NMR谱解析OA

One-dimensional proton nuclear magnetic resonance(NMR)spectroscopy is a high-resolution,non-invasive technique widely used for structure elucidation and composition analysis.However,when applied to complex systems,its effectiveness is often hampered by overlapping peaks from similar chemical shifts and J-coupling,along with concentration variations obscuring weak signals from low-abundance compounds.To enhance the detection sensitivity for weak signals in crowded spectral regions,this work proposes Hadamard-DQF-LMO,integrating longitudinal multi-spin orders(LMOs),Hadamard encoding,and double quantum filtering(DQF).The approach utilizes DQF to selectively detect LMO signals while suppressing strong interference.The incorporation of polychromatic transition pulses and Hadamard-encoded 180° pulses enables parallel acquisition of multiple frequencies,which significantly improves both sensitivity and detection efficiency.Experiments on orange juice and mixed amino acid samples demonstrate peak separation with enhanced selectivity and signal-to-noise ratio(SNR),offering a novel and effective strategy for the NMR analysis of complex systems.