DEPT NMR

DEPT is an acronym for Distortionless Enhancement by Polarization Transfer.

This experiment allows to determine multiplicity of carbon atom substitution with hydrogens.

For this purpose, three experiments need to be recorded, where pulse with φ₃ has flip angle of 45^o (a), 90^o (b), and 135^o (c).

Signs of signals in these experiments will reveal the substitution of carbon atoms:

• in a (DEPT-45) all signals will be positive
• in b (DEPT-90) only signals of CH groups will show
• in c (DEPT-135) signals from CH₂ will be negative, while CH and CH₃ - positive

ref
http://nmrwiki.org/wiki/index.php?title=DEPT ( NMR WIKI )