Solubility of hydroxyapatite by solid titration at pH 3-4
Solubility of hydroxyapatite by solid titration at pH 3-4
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DOI：
10.1016/j.archoralbio.2006.12.007
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发表时间：
2007-07-01
影响因子：
3
通讯作者：
Darvell, B. W.
中科院分区：
文献类型：
--
作者：
Pan, H.-B.;Darvell, B. W.
目的：羟基磷灰石（HAp）的溶解度等温线（S）对唾液化学、龋齿及相关环境具有重要意义。以前已经表明，S[HAp]的轨迹远低于通常报道的，并且具有不同的斜率，可能是由于HAp不一致溶解。本研究的目的是在较宽的pH范围内测定S[HAp]，并鉴定HAp固体滴定中平衡时形成的沉淀。唾液样介质中的钙-磷酸盐系统。J Chem Soc法拉第Trans 1991;87（11）：1759-64.）用于研究HAp在37.0 +/-0.1 ℃下在100 mM KCl水溶液中的溶解度行为。研究的pH值范围与早期工作的pH值范围重叠，从pH 3.6至5.2，用于重现性检查和验证，并扩展至pH值接近2.9。用XRD和EDX对沉淀物进行了表征。结果：与Chen等（Chen Z-F，Darvell BW，Leung VW-H.羟基磷灰石在简单无机溶液中的溶解度。口腔生物学文献2004;49（5）：359-67.）再次确认。在pH值接近3.9时检测到S[HAp]斜率的突变。在pH 3.2、3.6和4.1下，没有发现除HAp之外的其他相。特别是，透钙磷石（磷酸二钙二水合物）没有检测到，甚至低于pH 3.9，而不是钙缺乏HAp形成。结论：固体滴定法被重新确认为可重复的，并产生HAp从pH 2.9至5.2。预期的透钙磷石没有出现，而是稳定的缺钙HAp始终形成。磷酸钙的化学性质需要重新评估。(c)2006爱思唯尔有限公司保留所有权利。
Objectives: The solubility isotherm (S) of hydroxyapatite (HAp) is of fundamental importance to saliva chemistry, dental caries and related contexts. It has previously been shown that the locus of the S[HAp] is substantially lower than is commonly reported, and of different slope, probably due to HAps incongruent dissolution. The aim of the present study was to determine the S[HAp] over a wider pH range and to identify the precipitate formed at equilibrium in HAp solid titration.Methods: The solid titration technique of Leung and Darvell (Leung VW-H, Darvell BW. Calcium-phosphate system in saliva-like media. J Chem Soc Faraday Trans 1991;87(11):1759-64.) was used to investigate the solubility behaviour of HAp at 37.0 +/- 0.1 degrees C in 100 mM aqueous KCl. The pH range studied overlapped that of earlier work from pH 3.6 to 5.2, for a reproducibility check and validation, and extended to pH similar to 2.9. XRD and EDX were used to identify the precipitates. SEM and TEM were used to observe the morphology.Results: The previous S[HAp] reported by Chen et al. (Chen Z-F, Darvell BW, Leung VW-H. Hydroxyapatite solubility in simple inorganic solutions. Arch Oral Biol 2004;49(5):359-67.) was reconfirmed. An abrupt change of slope of S[HAp] was detected at pH similar to 3.9. No other phase than HAp was found at pH 3.2, 3.6 and 4.1. In particular, brushite (dicalcium phosphate dihydrate) was not detected, even below pH 3.9, where instead calcium-deficient HAp was formed.Conclusion: The solid titration method was reconfirmed as reproducible and to yield HAp from pH 2.9 to 5.2. The expected brushite did not appear, but rather a stable calcium-deficient HAp was consistently formed. The chemistry of calcium phosphates needs to be reevaluated. (c) 2006 Elsevier Ltd. All rights reserved.