17O 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 O-17-enriched water in biological systems. The occurrence of water which displays a residual O-17 quadrupolar splitting is demonstrated for the first time in a model biological system and an excised tissue sample. The resulting O-17 NMR spectra are shown to have the characteristics predicted in computer-simulated I = 5/2 NMR spectra. (C) 1998 Elsevier Science B.V. All rights reserved.