Abstract
A mineral specimen from Burgess, Canada, proved upon chemical and crystallographic analyses to be an exceptionally pure sample of fluorapatite. The over-all composition corresponds to
. The crystallographic c-axis was determined to be 6.865 Å, and the a-axis 9.374 A. Exchange data obtained by employing45Ca,32P, and18F indicate the presence of large crystallites with a specific surface of the order of 1 m2/g. It is indicated that the physical interpretation of the exchange process does not require the existence of separate departments, each with its own kinetic factor, but that the exchange may be simply related to the exponential change in the free energy of the reaction. For the reaction
the thermodynamic constant has been calculated to be 101.26, implying that fluorapatite always will form at the expense of hydroxyapatite under physiologic conditions. This transformation will be furthered by lowering the pH.
Résumé
Un échantillon minéral provenant de Burgess, Canada s'est révélé être un speciment exceptionnellement pur de fluoroapatite après analyse chimique et cristallographique. La composition globale de cet échantillon est la suivante:
. L'axe cristallographique C est de 6.865 A et l'axe a de 9.374 A. Des expériences d'échanges réalisés à l'aide de45Ca,32P et18F indiquent la présence de gros cristallites de surface spécifique de l'ordre de 1 m2/g. Il apparait que l'interprétation physique des processus d'échange ne nécessite pas l'existence de compartiments séparés, avec chacun son propre facteur cinétique, les échanges semblent être simplement liés à un changement exponentiel dans l'énergie libre de la réaction. Pour la réaction suivante:
, la constante thermodynamique de 101.26 a été calculée, suggérant que le fluorapatite se forme toujours aux dépens de l'hydroxyapatite dans des conditions physiologiques. Cette transformation se continue en abaissant le pH.
Zusammenfassung
Eine Mineralprobe aus Burgess, Kanada, erwies sich nach chemischer und kristallographischer Analyse als außergewöhnlich reines Fluorapatit. Die Gesamtzusammensetzung entspricht:
. Die kristallographische c-Achse wurde bestimmt und ergab 6,865 Å, und die a-Achse ergab 9,374 Å. Austauschwerte, welche durch Anwendung von45Ca,32P und18F erhalten wurden, deuteten auf große Kristalliten mit einer spezifischen Oberfläche von ca. 1 m2/g. Die Befunde deuten darauf hin, daß für die physikalische Erklärung des Austauschvorganges keine separaten Kompartimente mit eigenen kinetischen Faktoren nötig sind, sondern daß der Austausch mit dem exponentiellen Wechsel in der freien Energie der Reaktion in einfacher Beziehung steht. Für die Reaktion
wurde als thermodynamische Konstante 101,26 errechnet, was darauf deutet, daß unter physiologischen Bedingungen immer Fluorapatit auf Kosten von Hydroxyapatit entsteht. Diese Umwandlung wird erhöht, wenn das pH erniedrigt wird.
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Literature
Armstrong W. D., Singer, L.: Composition and constitution of the mineral phase of bone. Clin. Orthop.38, 179–190 (1965)
Collin, R. L.: Strontium-calcium hydroxyapatite solid solutions: preparation and lattice constant measurements. J. Amer. chem. Soc.81, 5275–5278 (1959)
Collin, R. L.: Strontium-calcium hydroxyapatite solid solutions precipitated from basic, aqueous solutions. J. Amer. chem. Soc.82, 5067–5069 (1960)
Costeas, A., Woodard, H. Q., Laughlin, J. S.: Comparative kinetics of calcium and fluoride in rabbit bone. Radiot. Res.46, 317–333 (1971)
Duff, E. J.: Orthophosphates. Part II. The transformation brushite-fluoroapatite and monetite-fluoroapatite in aqueous potassium fluoride solution. J. chem. Soc. (Lond.), Section A, 33–38 (1971)
Egan, E. P., Wakefield, Z. T., Elmore, K. L.: Low-temperature heat capacity and entropy of hydroxyapatite. J. Amer. chem. Soc.73, 5579–5580 (1951a)
Egan, E. P., Wakefield, Z. T., Elmore, K. L.: Thermodynamic properties of fluorapatite, 15 to 1600°K. J. Amer. chem. Soc.73, 5581–5582 (1951 b)
Falkenheim, M., Neuman, W. F., Hodge, H. C.: Phosphate exchange as the mechanism for adsorption of the radioactive isotope by the calcified tissues. J. biol. Chem.169, 713–722 (1947)
Farr, T. D., Elmore, K. L.: System CaO−P2O5−HF−H2O: thermodynamic properties. J. phys. Chem.66, 315–318 (1962)
Farr, T. D., Tarbutton, G., Lewis, H. T.: System CaO−P2O5−HF−H2O: equlibrium at 25 and 50. J. phys. Chem.66, 318–321 (1962)
Fiske, C. H., Subbarow, Y.: The colorimetric determination of phosphorus. J. biol. Chem.66, 375–400 (1925)
Gottschal, A. J.: Heats of formation of hydroxy-, fluor-, and chlorapatites. J. S. Afr. chem. Inst.11, 45–52 (1958)
Gulbrandsen, R. A.: Physical and chemical factors in the formation of marine apatite. Econ. Geol.64, 365–382 (1969)
Hagen, A. R.: Dental enamel in inorganic salt solutions. Oslo, Norway: Universitetsforlaget 1965
Hagen, A. R.: The state of fluorine in dentifrice systems. Acta odont. scand.30, 167–186 (1972)
Hodge, H. C.: The role of exchange in calcium and phosphate adsorption by the calcified tissues. In: Metabolic interrelations. Trans 1. Conf. Josiah Macy, Jr. Foundation (1949)
Hodge, H. C., Koss, W. F., Ginn, J. T., Falkenheim, F., Gavett, E., Fowler, R. C., Thomas, I., Bonner, J. F., Dessauer, G.: The nature of the insoluble sodium of bone. The adsorption of sodium at forty degrees by bone, dentin, enamel, and hydroxyapatite as shown by the radioactive isotope. J. biol. Chem.148, 321–331 (1943)
Holmes, J. M., Davies, D. H., Meath, W. J., Beebe, R. A.: Gas adsorption and surface structure of bone mineral. Biochemistry3, 2019–2024 (1964)
Ingram, G. S.: Some heteroanionic exchange reactions of hydroxyapatite. Bull. Soc. chim. Fr. Pt.II, 1841–1844 (1968)
Jacques, J. K.: The heats of formation of fluorapatite and hydroxyapatite. J. chem. Soc. (Lond.), 3820–3822 (1963)
Lagergren, C., Carlström, D.: Crystallographic studies of calcium and strontium hydroxyapatites. Acta chem. scand.11, 545–550 (1957)
Legeros, R. Z., Trautz, O. R., Legeros, J. P., Klein, E.: Carbonate substitution in the apatite structure. Bull. Soc. chim. Fr. Pt.II, 1712–1717 (1968)
Martens, C. S., Harriss, G. C.: Inhibition of apatite precipitation in the marine environment by magnesium ions. Geochim. Cosmochim. Acta34, 621–625 (1970)
McCann, H. C., Fath, E. H.: Phosphate exchange in hydroxyapatite, enamel, dentin, and bone. I. Mechanism of exchange. J. biol. Chem.231, 863–872 (1958)
Megirian, D.: The deposition of fluoride in glycol-ashed bone. Atomic Energy Project UR-128. The University of Rochester, 1951
Mooney, R. W., Aia, M. A.: Alkaline earth phosphates. Chem. Rev.61, 433–462 (1961)
Neuman, W. F.: Bone as a problem in surface chemistry. In Metabolic interrelations. Trans. 2. Conf. Josiah Macy, Jr. Foundation. 1950
Neuman, W. F., Neuman, M. W.: The nature of the mineral phase of bone. Chem. Rev.53, 1–45 (1953)
Neuman, W. F., Neuman, M. W., Main, E. R., Mulryan, B. C.: The deposition of uranium in bone. IV. Adsorption studies in vitro. J. biol. Chem.179, 325–333 (1949)
Neuman, W. F., Neuman, M. W., Main, E. R., Leary, J. O., Smith, F. A.: The surface chemistry of bone. II. Fluoride deposition. J. biol. Chem.187, 655–661 (1950)
Pak, C. Y. C., Bartter, F. C.: Ionic interaction with bone mineral. I. Evidence for an isoionic calcium exchange with hydroxyapatite. Biochim. biophys. Acta (Amst.)141, 401–409 (1967)
Philipson, T.: On the constitution of apatite minerals. Lantbrukshögskolans annaler29, 267–293 (1963)
Posner, A. S., Perloff, A., Diorio, A. F.: Refinement of the hydroxyapatite structure. Acta cryst.11, 308–309 (1958)
Prener, J. S.: The growth and crystallographic properties of calcium fluor-and chlorapatite crystals. J. electrochem. Soc.114, 77–83 (1967)
Singer, L., Armstrong, W. D.: Determination of fluoride in blood serum. Analyt. Chem.31, 105–109 (1959)
Singer, L., Armstrong, W. D.: Modified diffusion method for analysis of fluoride. J. dent. Res.41, 910 (1962)
Singer, L., Armstrong, W. D., Colman, L. M.: Microdetermination of calcium in biological materials. Analyt. Biochem.9, 217–223 (1964)
Smirnova, Z. G., Illarionov V. V., Vol'fkovich, S. I.: Heats of formation of fluorapatite, hydroxyapatite, and tricalcium phosphates (α and β modifications). Russ. J. inorg. Chem.7, 920–922 (1962)
Trautz, O. R.: X-ray diffraction of biological and synthetic apatites. Ann. N. Y. Acad. Sci.60, 696–712 (1958)
Valyashko, V. M., Kogarko, L. N., Khodakovskiy, I. L.: Stability of fluorapatite, chlorapatite and hydroxyapatite in aqueous solutions at different temperatures. Geochem. Intern.5, 21–30 (1968)
West, E. S., Christensen, B. E., Rivehart, R. E.: A micro-method for the determination of CO2 in blood and other fluids. J. biol. Chem.132, 681–686 (1940)
Young, R. A., Elliot, J. C.: Atomic-scale bases for several properties of apatites. Arch. oral Biol.11, 699–707 (1966)
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Hagen, A.R. Studies on fluorapatite. Calc. Tis Res. 13, 259–270 (1973). https://doi.org/10.1007/BF02015416
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DOI: https://doi.org/10.1007/BF02015416