NuMega Resonance Labs

Carbon NMR

For C-13 NMR, there are a 2 key factors to keep in mind during interpretation:

  • Signals: The number of unique carbons in a given spectrum.

  • Chemical Shift: The position of a carbon in a spectrum based on shielding and deshielding effects.

NMR Testing Services, Mass Spec, Elemental Analysis and Optical Rotation

The more deshielded a carbon is, the higher (downfield) the ppm value will be. While carbon NMR can be quantitative under certain test conditions, normally they are not integrated. Further experiments such as APT and DEPT experiments can give cues to how many attached hydrogens are on a particular carbon in the spectrum. Carbon NMR is usually run as a proton-decoupled experiment which means that the carbon signals do not split. Although uncommon, this experiment can be run as proton-coupled to show splitting patterns similar to what would be observed from a proton NMR.