The document discusses solvent selection for NMR spectroscopy. For proton NMR, deuterated solvents are preferred to avoid interference from solvent protons. Common deuterated solvents include deuterated water and chloroform. For carbon-13 NMR, any solvent can be used as the dominant carbon-12 isotope has no spin and does not appear in NMR. Deuterated solvents are still preferred to avoid interference from solvent protons. Trifluoroacetic acid can also be used as a solvent for proton NMR due to its proton signal appearing far downfield from the region of interest.