Just quoting in Danny Dorito so she can move the thread if needed
Why is the solvent used CDCl4 even though it contains a carbon, would this not invalidate the reading?
NMR spectra are usually measured using solutions of the substance being investigated. A commonly used solvent is CDCl3. This is a trichloromethane (chloroform) molecule in which the hydrogen has been replaced by its isotope, deuterium.
CDCl3 is also commonly used as the solvent in proton-NMR because it doesn't have any ordinary hydrogen nuclei (protons) which would give a line in a proton-NMR spectrum. It does, of course, have a carbon atom - so why doesn't it give a potentially confusing line in a C-13 NMR spectrum?
In fact it does give a line, but the line has an easily recognisable chemical shift and so can be removed from the final spectrum.