From The Environment To Nmr: Water Suppression For Whole Samples In Their Native State

Studying environmental samples in their natural state is critical as drying, fractionating or extractions can alter the composition, structure, conformation and biological activity, as well as perturb essential interfaces and domains. Nuclear magnetic resonance (NMR) spectroscopy is a powerful and versatile tool that provides unprecedented levels of information regarding structure and interactions. Both high-resolution magic-angle-spinning and comprehensivemultiphaseNMRprobes facilitate the study of natural multiphase samples. (1)HNMRspectroscopy is the most sensitive and provides unique information on swollen components and interfaces. However, samples such as plants, organisms and soil have a high aqueous content and a range of free, exchanging and bound water, leading to a broad and intense water signal that can span the entire H-1 spectral region masking information from other components. In this manuscript, a water suppression approach termed Tailored Water suppression for Inhomogeneous Natural Samples (TWINS) is developed out of a practical need to study samples in their native state. TWINS builds upon the most effective approach to date (SPR-W5WATERGATE) for natural samples with the addition of various elements to make the approach effective in the most challenging systems. TWINS was demonstrated on a range of environmental samples in both 1-D and 2-D NMR experiments. A lock capillary was developed to separate the lock solvent from the sample, further reducing sample alteration. In summary the more challenging the sample, the more TWINS outperformed conventional approaches. In turn this increases the range and diversity of samples that can be studied in their natural state critical for a wide variety of fields and applications.