Accurate relaxation measurements at a single low magnetic field, coupled with high-field data can also be used to validate the procedure implemented to estimate longitudinal relaxation rates from the decay rates at low field. Such an approach was implemented both for carbon-13 relaxation in methyl groups in ubiquitin and backbone nitrogen-15 relaxation in a disordered protein region. 55 Proteins are not the only type of biomolecule has been investigated by high-resolution relaxometry. For instance, Roberts and Redfield have investigated dynamics in a DNA octamer using P and 1 H field-cycling NMR. Internal order parameters for CSA interactions were determined, as well as overall correlation times for rotational diffusion but a precise determination of internal dynamics was not possible based on the analysis of 31 P relaxation alone.