Improved sensitivity and gradient-enhanced multiplicity edited two-dimensional heteronuclear shift correlation technique

A method that combines sensitivity and a gradient-enhanced two-dimensional heteronuclear shift correlation experiment with constant-time evolution during the t1 period, is proposed for multiplicity editing of the spectra at natural 13C abundance. In the resultant two-dimensional spectrum, the cross-peaks of CH and CH3 groups are negative whereas those of CH2 groups are positive in sign. We demonstrate the technique on a small biomolecule, cyclosporin A. It is observed that the sensitivity of the new multiplicity editing experiment (named as CT-PFG-PEP-HSQC) is comparable with that of the conventional PFG-PEP-HSQC experiment and therefore the new scheme can be useful for routine applications.