Solid state 31NMR studies of the conversion of amorphous tricalcium phosphate to apatitic tricalcium phosphate.
The hydrolytic conversion of a solid amorphous calcium phosphate of empirical formula Ca9 (PO4)6 to a poorly crystalline apatitic phase, under conditions where Ca2+ and PO4(3-) were conserved, was studied by means of solid-state magic-angle sample spinning 31P-NMR (nuclear magnetic resonance). Results showed a gradual decrease in hydrated amorphous calcium phosphate and the formation of two new PO4(3-)-containing components: an apatitic component similar to poorly crystalline hydroxyapatite and a protonated PO4(3-), probably HPO4(2-) in a dicalcium phosphate dihydrate (DCPD) brushite-like configuration. This latter component resembles the brushite-like HPO4(2-) component previously observed by 31P-NMR in apatitic calcium phosphates of biological origin. Results were consistent with previous studies by Heughebaert and Montel [18] of the kinetics of the conversion of amorphous calcium phosphate to hydroxyapatite under the same conditions.
Roberts
J E
JE
Francis Bitter National Magnet Laboratory, Massachusetts Institute of Technology Cambridge 02139.
Heughebaert
M
M
Heughebaert
J C
JC
Bonar
L C
LC
Glimcher
M J
MJ
Griffin
R G
RG
D001031:Apatites / Q000737:chemistry; D002130:Calcium Phosphates / Q000737:chemistry*; D003460:Crystallization; D006868:Hydrolysis; D009682:Magnetic Resonance Spectroscopy
D001031:Apatites; D002130:Calcium Phosphates; C485828:alpha-tricalcium phosphate; C519480:amorphous calcium phosphate; C485830:tetracalcium phosphate; C485838:calcium phosphate, monobasic, anhydrous; C020243:calcium phosphate; C485829:calcium phosphate, dibasic, anhydrous