Deuterated solvents are manufactured for use with NMR instruments. These solvents contain high chemical purity and maximum isotopic enrichment.
Deuterium signals from these solvents are used for an NMR lock system (also known as frequency-field lock) to avoid the fluctuations of the NMR magnetic field by off-setting the effect of natural drift. In order to provide deuterium lock, the NMR constantly monitors the deuterium signal resonance frequency from the solvent and makes changes to the magnetic field to keep the resonance frequency constant.
Deuterated solvents are often supplied with addition of small amount of TMS, tetramethylsilane, used as an internal standard for calibrating the chemical shifts of each analyte proton. Being a tetrahedral molecule, TMS is chemically equivalent with all its protons, giving only one signal. This signal is marked as a chemical shift of 0 ppm. TMS is volatile, making sample recovery easy as well. Modern spectrometers are able to reference spectra based on the residual proton in the solvent. Deuterated solvents are now commonly supplied without TMS.
Water contamination is a common problem for deuterated NMR solvents. Some deuterated solvents should be stored in the refrigerator (eg. chloroform-d ) to maximize shelf life.