Nuclear magnetic resonance spectroscopy (NMR spectroscopy) is a spectroscopic method to elucidate the structure of molecules and compounds. Due to electronic interactions of single atoms with the neighbouring atoms, structural conclusions can be drawn. In addition to structure elucidation, the concentration and dynamics of molecules can be determined with this method. This analytical method requires very precise tubes with a constant diameter, a uniform wall thickness and excellent straightness across the entire tube. Deposits and contamination in NMR tubes can be dissolved with the help of the NMR brush. Subsequent cleaning with a suitable solvent completely acidifies the NMR tube.