Concentration dependence of 19F nuclear magnetic resonance decay shapes and second moments in bone mineral

19F nuclear magnetic resonance (NMR) spin-echoes and free induction decays (FIDs) have been observed from samples of fluoridated trabecular canine bone powder, with fluoride concentrations ([F]) ranging from approximately 10 to 33 mg F/g Ca. Curve fitting of echo envelopes and FIDs was performed using a two-component model function, where one of the components incorporates the effects of one-dimensional dipolar coupling. This function provides a good match for both echo envelopes and FIDs. Estimates of the total second moment and its homonuclear (F-F coupling) component were obtained from the fitting procedure. Based on the second moment measurements, it is argued that 19F spins in bone mineral typically experience weaker heteronuclear dipolar coupling than those in the mineral hydroxyapatite (HAP), which is often considered to be a prototype for bone mineral.