Drug Metabolism in Drug Design and Development Basic Concepts and Practice

TABLE 12.8 Common solvent suppression methods.Suppression sequence

Setup

Advantages

Limitations

Presaturation

Traditionally, the solvent signal is

irradiated for a period of timewith a continuous wave rf field

Can be easily set up Useful for

eliminating single solvent signal.

Extremely sensitive to spectro-

meter stability and shimming.Not easy to suppress multiplesolvent peaks simultaneously.

Also, suppresses exchange peaksSuppresses NMR signals from the

compound that overlaps withthe solvent.

Excitation

sculpting

The solvent resonances are

extracted from the spectrawith selective pulses

Involved setup, could be auto-

mated, exchange resonances arenot suppressed, multiple solventpeaks can be suppressed.Extremely flat baselines.

Setup is involved. Several

elements in the pulse sequenceneed to be optimized

Suppresses NMR signals from the

compound that overlap with thesolvent

Watergate

exitationtechnique(WET)

The solvent resonances are

selectively suppressed at thebeginning of the NMRexperiment. This pulsesequence is the most widelyused solvent suppressiontechnique for LC–NMRexperiments

Involved setup, could be automated,

exchange resonances are notsuppressed, multiple solventpeaks can be suppressed. 13

C

decoupling

Suppresses NMR signals from the

compound that overlaps withthe solvent

Baseline distortions

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