A Pure Shift-Based NMR Method for Transverse Relaxation Measurements on Complex Samples

Transverse spin-spin (T ₂ ) relaxation provides a significant insight into molecular dynamics and interactions, and the determination of T ₂ relaxation times constitutes an important evaluation metric in nuclear magnetic resonance (NMR) applications. However, two major limitations of spectral congestion and high radio frequency power deposition are generally encountered in conventional Carr-Purcell-Meiboom-Gill-based experiments, thus hindering accurate T ₂ relaxation measurements. Herein, we present an NMR method based on pure shift techniques to avoid these two limitations and achieve T ₂ relaxation measurements on complex samples that contain crowded NMR resonances. We perform detailed theoretical analyses for the proposed method to explicitly understand its basic mechanism. Experiments on a simple chemical solution, a complex sample of estradiol, and a medicine sample of azithromycin are carried out to illustrate feasibility and applicability of the proposed method. Both theoretical analyses and experimental results show the ability of the proposed method for T ₂ relaxation measurements on complex samples and its potential for practical applications.