title: Natural abundance 43Ca solid-state NMR characterisation of hydroxyapatite: identification of the two calcium sites.
abstract: Natural abundance (43)Ca solid-state NMR of hydroxyapatite (Ca(10)(PO(4))(6)(OH)(2)) was performed at three different fields (8.45, 14.1 and 18.8 T). The two crystallographically distinct calcium sites of the apatite structure were spectroscopically resolved at 18.8 T. The (43)Ca NMR interaction parameters (delta(iso), C(Q) and eta(Q)) of each site were determined by multiple magnetic-field simulations. The peaks with delta(iso) = 11.2 +/- 0.8 and - 1.8 +/- 0.8 ppm, both with C(Q) = 2.6 +/- 0.4 MHz, were assigned to the Ca(II) and Ca(I) sites, respectively, on the basis of their relative intensities.
authors.affiliation: Department of Physics, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, United Kingdom, UK.
authors.forename: Danielle
authors.initials: D
authors.lastname: Laurencin
authors.forename: Alan
authors.initials: A
authors.lastname: Wong
authors.forename: Ray
authors.initials: R
authors.lastname: Dupree
authors.forename: Mark E
authors.initials: ME
authors.lastname: Smith
mesh_terms: D002118:Calcium / Q000737:chemistry*; D002127:Calcium Isotopes; D017886:Durapatite / Q000138:chemical synthesis / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods* / Q000592:standards; D015394:Molecular Structure; D012015:Reference Standards
chemical_list: D002127:Calcium Isotopes; D017886:Durapatite; D002118:Calcium