Solubility of the three calcium oxalate hydrates in sodium chloride solutions and urine-like liquors
Solubility of the three calcium oxalate hydrates in sodium chloride solutions and urine-like liquors
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DOI：
10.1007/pl00010134
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发表时间：
1998-12-01
影响因子：
1.8
通讯作者：
Königsberger, E
中科院分区：
文献类型：
--
作者：
Streit, J;Tran-Ho, LC;Königsberger, E
草酸钙形成三种水合物（稳定的单斜晶一水合物（COM）、亚稳的四斜晶二水合物（COD）和三斜晶三水合物（COT）），其在泌尿结石形成中具有医学重要性。在这项工作中，这些草酸钙水合物的溶解度是在20，25，30，37，和40摄氏度的NaCl水溶液（0.02-0.20 mol.dm（-3））和尿液样液体。此外，第一次，COM的溶解度作为一个功能的pH值的人工尿液中含有有机化合物进行了系统的研究。用钙离子选择电极连续测定钙离子浓度，并用原子吸收光谱法测定。热力学溶度积是从计算机模拟中得到的，其中考虑了在水溶液中形成的所有可能的络合物。这些值进行了比较，可在文献中，它被发现，目前的结果，特别是COD和GOT，构成了一个重大的改进，以前报道的值。利用测定的溶解度常数预测了不同pH值下水合草酸钙在尿液中的溶解度。结果发现，在人工尿液中，柠檬酸盐和镁离子促进COM的溶解，而尿素和肌酐没有显着的影响。
Calcium oxalate forms three hydrates (stable monoclinic mono-hydrate (COM), metastable tetragonal dihydrate (COD) and triclinic trihydrate (COT)), which are of medical importance in urinary calculi formation. In this work, the solubility of these calcium oxalate hydrates was determined at 20, 25, 30, 37, and 40 degrees C in aqueous NaCl (0.02-0.20 mol.dm(-3)) and in urine-like liquors. Also, for the first time, the solubility of COM was systematically studied as a function of pH in artificial urine solutions which contain organic compounds. The concentrations of calcium ions were measured continuously using a calcium ion selective electrode and also determined by AAS. The thermodynamic solubility products were obtained from computer simulations in which all possible complexes formed in aqueous solution were taken into account. These values were compared to those available in the literature; it was found that the present results, especially for COD and GOT, constitute a major improvement on the previously reported values. The constants determined in this work were used to predict the solubility of calcium oxalate hydrates at different pH in urine-like liquors. It was found that in artificial urine solutions, citrate and magnesium ions promote the solubility of COM, whereas urea and creatinine have no significant effect.