*4.3.4.3.2 Distortionless enhancement by polarization transfer (DEPT)*

It is an improved method of INEPT, in which a *J*-modulation is accompanied by a polarization transfer from the protons to coupled carbons, leading to significant improvement in sensitivity. In DEPT spectrum, by changing the pulse width (*θ*), which could be designed as 45o , 90o , and 135o , during irradiation of 1 H, different carbons could show different strengths and signs. The results are similar with INEPT spectrum. When *θ* = 45o , all CH, CH2, and CH3 groups display positive signals; when *θ* = 45o , only CH groups show positive signals; when *θ* = 135o , both CH and CH3 groups show positive signals, while CH2 groups show negative signals. Quarterly carbons show no signal peaks in DEPT spectra. An example of DEPT spectra is shown in **Figure 5**.
