PROCESSING YOUR DATA

DC Offset

During the acquisiton of an NMR signal, the data may be shifted slightly in the vertical direction. This corresponds to a small DC (for direct current), or constant voltage being added to the entire signal. After Fourier transformation, this DC offset results in an artifact, or glitch, in the final spectrum. Glitches can be confused with real peaks, so it is good practice to ensure that the data are centered around zero voltage.

Move mouse into and out of the figure area below to see what a DC offset of the FID looks like. To view its effects on spectra, scroll down or click here.

The Fourier Transform of the DC offset is a sharp spike. In a spectrum, this appears as a glitch, which may be confused with a peak. To compare the results of transforming data with and without an offset, move the mouse into and out of the areas below.