Brecević L, Füredi-Milhofer H
Calcif Tissue Int. 1979 Oct 31;28(2):131-6. doi: 10.1007/BF02441231.
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.
研究了柠檬酸根离子对低钙磷摩尔比的结晶磷灰石沉淀[八钙磷酸酯（OCP）和缺钙磷灰石（DA）（体系A）]以及磷酸二氢钙二水合物（DCPD）与DA的晶间混合物（体系B）沉淀的影响。通过直接混合含有柠檬酸盐（0 - 2.10(-3) mol dm-3）并预先调节至pH 7.4的氯化钙溶液（A，6.10(-3) mol dm-3；B，1.10(-1) mol dm-3）和磷酸钠溶液（A，6.10(-3) mol dm-3；B，2.10(-2) mol dm-3）来制备样品。在柠檬酸根离子存在的情况下：（a）OCP和DA的晶体生长减慢；（b）DCPD晶体的习性发生改变；（c）DCPD与DA的晶间混合物中的平衡减慢。所有这些现象都是由带负电荷离子的表面吸附引起的，很可能是CaC6H5O7-，它是在给定实验条件下占主导的柠檬酸钙物种。DCPD的习性改变是由在（001）晶面的优先吸附诱导的。
