The selective 1D HMQC-TOCSY experiment is the selective version of the 2D HMQC-TOCSY experiment. As in the conventional TOCSY experiments, it allows to obtain ¹H subspectra but from a selected ¹³C nucleus. This experiment has also been used to measure long-range proton-carbon coupling constants.

Easy implementation on AVANCE spectrometers equipped with an inverse probehead and selective excitation using shaped pulses.

The selective 1D HMQC-TOCSY pulse sequence is easily derived from the conventional 2D HMQC-TOCSY experiment in which one of the two 90º ¹³C pulses is made selective for a given ¹³C resonance and the variable evolution delay is fixed to a minimum value ( 90MRC696 and 90TL5273 ). In other words, it consists of a selective 1D HMQC pulse train followed by a TOCSY block. A BIRD-recovery delay cluster can be incorporated as a preparation period to suppress the large and undesired ¹H-¹²C magnetization.
 
Related modified sequences have been proposed:

• Analog selective 1D HSQC-TOCSY ( 94JMRA94-107 and 94JMRA95-110 ) and selective 1D reverse-INEPT-TOCSY ( 94JMRA94-107 , 94JMRA90-110 , and 94JMRA95-110 ) experiments have also been proposed for the same purpose.
• Better results are obtained from the gradient-enhanced version (see selective ge-1D HMQC-TOCSY experiment).
• Measurement of long-range proton-carbon coupling constants ( 94JMRA119-106 ).
• Analog experiments are used to measure long-range ¹H-¹³C coupling constants by recording two separate 1D spectra from the alpha and beta ¹³C spin states ( 94MRC97 , 94JMRB284-103 , 94JMRA103-108 , 94JMRA262-110 , 95JMRA267-117 , 96JMRA105-123 , 96JMRA260-119 , and 96JMRA117-118 ).
• Use of a ¹³C chemical shift-selective filter ( 94JMRA119-106 ).
• Application on ³¹P has been reported ( 93JMRA304-105 ).

The selective 1D HMQC-TOCSY  experiment can be recorded in a fully automated way. Minor changes from a predefined parameter set are required. The most important parameters to define is the TOCSY mixing time and the selective ¹³C pulse: the offset, the shape, the duration and the power level needed for a specific excitation profile.

For further details on practical implementation of the selective 1D HMQC-TOCSY  experiment on AVANCE spectrometers see Tutorial: selective 1D HMQC-TOCSY experiment

The selective 1D HMQC-TOCSY experiment affords a ¹³C-edited 1D TOCSY spectrum from the selected ¹³C resonance. It can be an useful alternative to achieve 1D ¹H subspectra in high overlapped regions. The direct response appears as a large doublet due to ¹J(CH) if no ¹³C decoupling is applied during acquisition while all other ¹H nuclei belonging to the same spin system will also show the residual long-range ¹H-¹³C coupling constant (ⁿJ(CH)) with respect to the selected ¹³C nucleus. However, accurate measurement of even tiny ⁿJ(CH) values can be obtained by recording two separate selective 1D HMQC-TOCSY spectra on each line (alpha and beta state) of the ¹³C doublet resonance of the corresponding ¹H-coupled ¹³C spectrum.