Precipitation of calcium phosphates from electrolyte solutions. V. The influence of citrate ions.
Calcif Tissue Int, 1979/10/31;28(2):131-6.
PMID: 116729
Impact factor: 4
Abstract
The influence of citrate ions on the precipitation of crystalline apatitic precipitates with low Ca/P molar ratios [octacalcium phosphate (OCP) and calcium-deficient apatites (DA) (system A)] and of the intercrystalline mixtures of calcium hydrogen phosphate dihydrate (DCPD) and DA (system B) was investigated. Samples were prepared by direct mixing of calcium chloride solutions (A, 6.10(-3) mol dm-3; B, 1.10(-1) mol dm-3) and sodium phosphate solutions (A, 6.10(-3) mol dm-3; B, 2.10(-2) mol dm-3) containing citrate (0-2.10(-3) mol dm-3) and preadjusted to pH 7.4. In the presence of citrate ions: (a) crystal growth of OCP and DA was slowed down; (b) habit modification of DCPD crystals occurred; and (c) equilibration in intercrystalline mixtures of DCPD and DA's was slowed down. All phenomena were caused by surface adsorption of negatively charged ions, most probably CaC6H5O7-, which is the prevalent calcium citrate species under the given experimental conditions. Habit modification of DCPD was induced by preferential adsorption at the (001) crystal plane.
MeSH terms
Calcium; Calcium Phosphates; Chemical Phenomena; Chemical Precipitation; Chemistry, Physical; Citrates; Crystallization; Electrolytes; Ions; Phosphorus; Solutions
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