An in-depth structural characterization of marine dissolved organic matter (DOM) is crucial for a better understanding of its connection to marine and global biogeochemical cycles. High-field nuclear magnetic resonance (NMR) spectroscopy in general and two-dimensional (2D) correlation spectroscopy (COSY) in particular are powerful tools for the molecular level structural analysis of marine DOM. These 2D NMR experiments demand prolonged experimental times of days to weeks per sample due to the requirement of a large number of experiments to record the second dimension (t₁) of the 2D NMR experiment. Herein, we demonstrate the efficacy of nonuniform sampling (NUS) in 2D COSY, which (i) reduces the measurement time by half without compromising spectral quality and (ii) enhances the signal intensity for the given experiment time. This approach can lead to substantial progress in the structural analysis of previously poorly characterized marine DOM. NUS COSY has been exemplified on two solid-phase extracted DOM samples from the surface and deep ocean at 800 MHz and 1.2 GHz instruments. A dramatic improvement in sensitivity and spectral resolution is observed in NUS COSY spectra recorded at 1.2 GHz instrument when compared to 800 MHz instrument. NUS COSY NMR is versatile and anticipated to have significant potential for uncovering the hidden molecular diversity of DOM from various aquatic environments within a reasonable timeframe. The introduction of NUS into the environmental sciences was long overdue, and our study now opens the door for a wide field of new applications of NMR in the marine and aquatic sciences.

中文翻译：

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用于海洋溶解有机物结构表征的快速高效工具：非均匀采样 2D COSY NMR

海洋溶解有机物（DOM）的深入结构表征对于更好地了解其与海洋和全球生物地球化学循环的联系至关重要。高场核磁共振 (NMR) 光谱和二维 (2D) 相关光谱 (COSY) 是海洋 DOM 分子水平结构分析的有力工具。由于需要进行大量实验来记录第二维 ( t ₁）的二维核磁共振实验。在此，我们展示了 2D COSY 中非均匀采样 (NUS) 的功效，它 (i) 在不影响光谱质量的情况下将测量时间减少一半，并且 (ii) 增强了给定实验时间内的信号强度。这种方法可以使之前描述不佳的海洋 DOM 的结构分析取得实质性进展。NUS COSY 已在 800 MHz 和 1.2 GHz 仪器下从表面和深海固相提取的两个 DOM 样本中进行了验证。与 800 MHz 仪器相比，在 1.2 GHz 仪器记录的 NUS COSY 光谱中观察到灵敏度和光谱分辨率显着提高。NUS COSY NMR 用途广泛，预计具有在合理的时间范围内揭示各种水生环境中隐藏的 DOM 分子多样性的巨大潜力。新加坡国立大学早该将其引入环境科学领域，而我们的研究现在为 NMR 在海洋和水生科学中的广泛新应用打开了大门。