Fig. 10.

¹⁷O Double frequency sweep NMR spectra of (fresh) sheep bone (blue), OCP-citrate (red), 5% ¹⁷O-enriched hydroxyapatite (green), and bone mineral soaked in aqueous citric acid (cyan). The individual spectra have been scaled so that the magnitude of the apatitic orthophosphate peak (truncated) is equal to that from bone to compare the relative nonapatitic phosphate populations. The oxygen site giving rise to each signal is highlighted in red. The signals below 0 ppm are caused by water, and those signals above 150 ppm are caused by organic compounds (the organic matrix in the bone samples and citrate in OCP-citrate and the bone soaked in aqueous citrate) as indicated.