(17)O NMR of water in ordered environments

Two NMR experiments are designed for selective excitation of spin I=5/2 nuclei that exhibit residual quadrupolar splittings. The I=5/2 Jeener-Broekaert experiment is preferred to the four-quantum filtration experiment as it is shown to be a more sensitive technique in experimental practice. Both techniques are applied to (17)O-enriched water in biological systems. The occurrence of water which displays a residual (17)O quadrupolar splitting is demonstrated for the first time in a model biological system and an excised tissue sample. The resulting (17)O NMR spectra are shown to have the characteristics predicted in computer-simulated I=5/2 NMR spectra.