Distortionless Quantitative ~(13)C DEPT~(++) Experiment

Polarization transfer 13 C NMR techniques, such as DEPT and its modified versions(i.e., DEPT++, Q-DEPT and Q-DEPT+), are frequently used in the analysis of complex mixture, given its high sensitivity and resolution. However, the practical use of quantitative DEPT experiments are often hampered by spectral distortions, which makes accurate quantification difficult. In this study, we incorporated elements of the Q-DEPT sequence into the DEPT++ pulse sequence, with the aim to eliminate spectral distortions in Q-DEPT+. The polarization transfer mechanisms underlying DEPT++ were analyzed. It was found that it is possible to obtain distortionless spectrum in quantitative DEPT++ experiment simply by calibrating the flip angle of the read pulse.