Water suppression

In NMR spectra solvent peaks often obscure the peaks of interest. Using deuterated solvents is one way to avoid this problem, but solubility or the need to observe exchangeable protons such as hydroxyls and amides sometimes requires using a protonated solvent. This is often the case when trying to use physiological conditions, as in biomolecular NMR or metabolomics. To detect the solute in aqueous solutions the water peak must be suppressed and there are several different ways this can be achieved.

Gradients for solvent suppression

The previous post described how a combination of gradients and pulses can be used to help reduce artifacts in NMR spectra. Adding a selective pulse to that sequence enables solvent signals to be excluded. This technique, sometimes known as excitation sculpting, is described below.