WaterControl: self-diffusion based solvent signal suppression enhanced by selective inversion.

Selective inversion/excitation based solvent signal suppression techniques are widely used in various NMR experiments because of their high efficiency and general applicability. However, these techniques generate a 'null'/suppression region containing (non-quantitatively) degraded solvent and desired resonances because of their reliance on the rejection of the coherence transfer pathway corresponding to all the resonances within the suppression region. To address this issue, the WaterControl technique was developed by inserting a (pulsed gradient - selective inversion pulse - pulsed gradient) unit into each 'transverse' period of a standard stimulated echo pulse sequence so that the coherence transfer pathways corresponding to both the suppression and non-suppression regions can be selected in one transient. The new sequence affords a diffusion based and quantifiable solvent signal suppression with no or minimal loss of features of interest.