Recommendations for Sample Preparation

High quality data begins with a high quality sample. Please use NMR tubes that are appropriate for the spectrometer frequency and application you plan to work with. Vendors like Aldrich, Wilmad, Norell, etc., offer several grades of NMR tubes that include anything from disposable to high quality glass tubes. If you have questions concerning the type of NMR tube need for your experiment please let me know and I'll be happy to help you select the right one.

Recommended sample volumes are 550ml for regular 5mm tubes, 270-330ml for Shigemi tubes, and 270ml for Squashed (3x6 mm) Shigemi tubes. Make sure your sample has no bubbles, no precipitate at the bottom of the NMR tube, and that it isn’t cloudy. Finally, Wipe the tube with a lint-free tissue to remove fingerprints and/or other impurities before inserting it into the magnet.

Preferred NMR buffers for Biomolecular experiments are those without protons that can give large background signals. Phosphate-based buffers are used very commonly. Other buffers like TRIS, HEPES, etc., and additives like DTT, BME, and detergents can also be used but they all have protons. Deuterated versions of many of these chemicals are available at high cost and therefore are only used when it is absolutely necessary. The use of 0.04% Sodium Azide is highly recommended to avoid growth of microorganisms for samples used in multiday experiments. The common pH range for HN-directed experiments is between 4 and 7.5. Higher pH will promote HN exchange with the buffer and reduce the number of signals in your experiment.

Samples with high salt concentrations, > 150 mM, loaded in round 5 mm NMR tubes are not recommended when using cold probes. The Biomolecular NMR facility has a couple of salt tolerant cold probes (Apollo and Pele800) that allow measurments on salty samples but require the use of Squashed (3x6 mm) Shigemi NMR tubes.