High Quality Content by WIKIPEDIA articles! Oxygen-17 is a low abundant isotope of oxygen (0.0373% in seawater; approx. twice as abundant as Deuterium). Being the only stable isotope of oxygen possessing a nuclear spin and the unique characteristic of field-independent relaxation it enables NMR studies of metabolic pathways of compounds incorporating oxygen at high magnetic fields (i.e. metabolic H217O water produced by oxidative phosphorylation in mitochondria).