Nuclear Magnetic Resonance Spectroscopy:

Chemical Shift:

It is convenient to describe the relative positions of the resonances in an NMR spectrum. For instance, as shown in Figure 35.07, a peak at a chemical shift, δ, of 10 ppm is said to be downfield or deshielded with respect to a peak at 5 ppm. Otherwise, the peak at 5 ppm is upfield or shielded with respect to the peak at 10 ppm.

Figure 35.07: Schematic representation of de-shielded and shielded in NMR spectrum.

Taking the example shown in Figure 35.06, we can conclude that the peak at 4.8 is downfield or deshielded with respect to peak at 3.35 or the peak at 3.35 is upfield or shielded to peak at 4.8 ppm.