Question

In spectroscopy, why is it often useful to run a blank sample?

Answer 1

Typically, we perform a spectroscopic experiment in some form of solvent.......

Explanation:

And the spectrometer, whatever sort it is, reports on the absorption of (i) the sample you investigate; and (ii) the solvent in which it is dissolved. For many experiments, the absorption due to the solvent, the carrier, is negligible, and may be ignored; of course for others, the absorption due to the solvent is non-negligible, and we must account for it........

In NMR spectroscopy we usually use a deuterated solvent, which serves two functions: it is a deuterium source, to which the spectrometer locks onto; and (ii) it dissolves the sample WITHOUT introducing extra hydrogen nuclei whose absorption would swamp that of the analyte.....

And thus, whatever form of spectroscopy you use, it is usually a good idea to run a blank sample to establish the background spectrum.