SENSITIVITY IMPROVEMENT IN PROTON-DETECTED 2-DIMENSIONAL HETERONUCLEAR CORRELATION NMR-SPECTROSCOPY

The sensitivity of proton-detected two-dimensional heteronuclear correlation NMR spectroscopy can be increased by as much as a factor of √2 relative to that of the conventional methods, for heteronuclei with a single attached proton. The enhanced sensitivity is obtained by refocusing and detecting two orthogonal in-phase proton magnetization components, rather than the single component recorded conventionally. The two magnetization components are deconvoluted to produce two pure-phase spectra that are added together to produce a spectrum with an enhanced signal-to-noise ratio. Methods for improving the sensitivity of the main classes of heteronuclear correlation experiments are presented and the effect of relaxation during the new experiments on the sensitivity enhancement is discussed. The new methods are demonstrated by comparing conventional and sensitivity-enhanced 1H-15N heteronuclear correlation spectra of bovine pancreatic trypsin inhibitor at 15N natural abundance. © 1991.