Drug Metabolism in Drug Design and Development Basic Concepts and Practice

TABLE 12.2 Common NMR hardware and its new developments.

Conventional design

New developments

Advantages

Magnet

Super conducting

magnet.

Shielded and ultra shielded magnet.

The extra outer magnet coil cancelsthe stray field from the inner coil ofthe magnet to reduce the 5-gauss linesignificantly

Field strength could go up to 900 MHz.High stability and homogeneity.

Shielded magnets need much smaller spaceto site a magnet

It is easy to couple the NMR spectrometer with

mass spectrometer or HPLC systems.

Probe

5 mm or 3 mm CH

dual probe, QNPprobe, TXI probe,Broadband probe.

Cryocooled probe in which the probe

rf coil and the preamplifier are closeto liquid helium temperature

The sensitivity of

1 H

and

13

C

is three to four

times higher than that of a conventional probe.

Significant reduction in time for 2D NMR

experiments1D

1 H

can be obtained with as

little as 10 ng of compound

Capillarycoil probe that with a receiver

coil that is 10–100 times smallerthan that of the conventional probe.

High mass sensitivity Less sample and solvent

consumption

Flow (tubeless) probe that use direct

injection (manual or automatic) todeliver sample to the flow cell.

Can be directly coupled with HPLC and MS

spectrometer (NMR–HPLC–MS).Is used for 96- or 384-plate analysis in a highthroughput mode.

Console and

computer

It consists of

robust components:frequency generator,radio frequency andgradient amplifiers,interface board,shimming boardand signal generatorand detector.

Digital-signal

processor.Fastercomputer.Noise freeand linear amplifiers.Gradient shimming.

Increases linearity

of excitation overwider range ofexcitationImprovements inbaselineReducedprocessing timefor large data sets

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