Suppression or differentiation of solvent resonance by a combination of DEFT with a two-dimensional sequence

A new pulse sequence is described which combines the driven equilibrium Fourier transform (DEFT) and 2D pulse scheme, and allows simultaneous suppression of the solvent peak (H₂O/D₂O) in 1D and 2D experiments without perturbing the nearby solute signals. To overcome the sensitivity problem, and to allow for 2D experiments in a reasonably short time, a steady-state condition was set up by adjusting τ₁ (pulse delay) and D (recycle delay) to be 2-4 times the longest spin-lattice relaxation time T₁ (peptide) such that M_z (solvent) was nulled prior to the 2D pulse sequence. Longitudinal and transverse relaxation rates of the solvent were analyzed in the steady state, and a direct calculation of T₁ (solvent) was performed using an equation derived in the present work. This novel pulse sequence is also extended to 2D NOE experiments with effective solvent suppression. The method is demonstrated in a variety of 1D and 2D experiments on the cyclic delta opioid receptor selective peptide {A figure is presented}.