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Properly prepare your sample -- Make sure your sample is "clean" | ||||||
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Make sure your tube is clean, i.e. avoid another "reference spectrum" of acetone. Cleaning the tube in HNO3 is good. It removes metal contaminants. Even new tubes and caps should be cleaned, especially if you have a dilute sample. | ||||||
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Avoid stop-cock grease contamination, especially if you have peaks near 0 ppm | ||||||
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Use the right amount of sample. As the molecular weight of your sample increases, use the higher range of the sample weights given below. The bottom end of the ranges works adequately for a sample of about 220 g/mole.
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Suspension, gels, and solid material degrades spectral quality. Too much sample gives a poor quality spectrum. | ||||||
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Use a deuterated solvent. Don't use an "old" solvent. Old bottles are often contaminated with water or other compounds. DMSO is very good at picking up contaminants. In the case of CDCl3, there is the strong possibility of HCl also being present. | ||||||
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Don't add TMS nor use a solvent with added TMS. The best option is to either pipette some vapor from the TMS bottle into your sample or to add a drop of solvent with 1% TMS. | ||||||
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Don't make sample volume too small, ~ 0.50 ml is fine. In adequate solvent volume will make shimming difficult and time consuming. If you have multiple samples, make them all the same volume! | ||||||
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Don't make a sample with more than 0.50 ml. Excessive solvent wastes money on expensive deuterated solvents. If the sample does not lock either no deuterated solvent is present or the amount is too small. Check the reference standard for lock. | ||||||
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Read a protocol for sample preparation. |
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