Single Line or Multiplet Suppression Experiment

Depending on the type of sample and spectrometer configuration there are three main selective signal suppression methods  

Selective suppression of a single line or a multiplet which belongs to a high concentration compound, particularly solvents or byproducts 

Different principles are used (1) presaturation method presaturation of the signal, (2) jump-and-return method excitation of all signals followed by transfer of solvent coherence into not-detectable equilibrium magnetization of the solvent, (3) WATERGATE gradient driven destruction of solvent coherence 

Variants Presaturation technique [5.13], jump-and-return technique [5.14], 

As discussed in the introduction to this section, the presaturation method is the simplest experiment since the suppression is based on either cw irradiation or a shaped selective pulse. The method is not recommended for solvents such as water or methanol if protons of the compound under investigation exchange with the presaturated protons of the solvent, since the resonance signal of these protons would also be presaturated and disappear. Consequently the presaturation method should not be used for sugars, proteins etc. if the amid, imid or hydroxyl protons are of particular interest. 

---