Interpreting ¹³C spectra:

Generally, ¹³C spectra of very well known structures can be interpreted in the following stages. 1^st, the number of non-equivalent carbon atoms is counted by counting the number of signals present in the spectrum, apart from those signals because of the internal reference (TMS at 0 ppm) or the solvent. The signal for CDCl₃ is a triplet (1:1: 1) at 77 ppm (caused via coupling to the deuterium atom in which I=1).

Second, each signal is recognized as CH₃, CH₂, CH or quaternary by using off resonance decoupling or DEPT spectra.

Third, the chemical shifts of the signals are calculated, and then compared with the theoretical chemical shifts for the carbons present in the molecule. There are a range of tables and equations that can help in this analysis but it should be noted that the make use of such type of tables is not as straightforward as for ¹H nmr analysis. Though, software packages are now available that can calculate the theoretical chemical shifts for organic structures. These are frequently incorporated into chemical drawing packages like ChemDraw.