Distortionless enhancement through polarization

In practice, however, we rarely collect a H-coupled spectrum because of the poor sensitivity associated with this experiment. More elegant experiments that require less instrument time are available to provide similar information. These experiments include the attached proton test (APT) [1] and the distortionless enhancement through polarization transfer (DEPT) [2] experiments. Careful examination of data generated by the heteronuclear multiple quantum... 

Distortionless enhancement through polarization transfer, DEPT. A C-detected onedimensional experiment that can determine the number of Fi s bound to a C. 

Two important 1-D experiments that make use of J-couplings are the attached proton test (AIT) and the distortionless enhancement through polarization transfer (DEPT) experiment. Both the APT and DEPT experiments provide information about whefber or not the observed nucleus—virtually always —is protonated, and if so,... 

DEPT. Distortionless enhancement through polarization transfer. 

Figure 15 Pulse sequence and detected signal for the distortionless enhancement through polarization transfer (DEPT) experiment used to identify peak multiplicity.

Determination of the number of directly bound hydrogen atoms, called multiplicity assignment, is easy through application of editing pulse sequences, e.g., distortionless enhancement by polarization transfer (DEPT) or attached proton test (APT). 

Of the multitude of ID 13C NMR experiments that can be performed, the two most common experiments are a simple broadband proton-decoupled 13C reference spectrum, and a distortionless enhancement polarization transfer (DEPT) sequence of experiments [29]. The latter, through addition and subtraction of data subsets, allows the presentation of the data as a series of edited experiments containing only methine, methylene and methyl resonances as separate subspectra. Quaternary carbons are excluded in the DEPT experiment and can only be observed in the 13C reference spectrum or by using another editing sequence such as APT [30]. The individual DEPT subspectra for CH, CH2 and CH3 resonances of santonin (4) are presented in Fig. 10.9. 

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