Distortionless Enhancement by Polarization Transfer — DEPT

Distortionless Enhancement by Polarization Transfer (DEPT) is a carbon based NMR experiment that can aid in distinguishing between primary, secondary, tertiary, and quaternary carbons.

The combination of DEPT and C-13 can define how many protons are attached to a particular carbon. Varying the flip angle provides different information about the number of attached protons. DEPT-45 experiment shows -CH, -CH₂, and -CH₃ groups all as positive signals. DEPT-90 experiment only shows -CH groups as positive signals. DEPT-135 shows -CH and -CH₃ as positive signals while -CH₂ are shown as negative signals. Above is an example of ibuprofen and a recreation of how the DEPT spectra should appear for comparison of methods.