柠檬酸二乙酯与钙离子配合物的组成、稳定常数及其影响因素.docVIP

 柠檬酸二乙酯与钙离子配合物的组成、稳定 常数及其影响因素# 陈斌1，欧研2，桂保松2，欧阳健明1** 5 10 15 20 25 30 35 40 （1. 暨南大学生物矿化与结石病防治研究所，广州 510632； 2. 西安交通大学第二医院肾内科，西安 710004） 2+ 配合物的组成、稳定常数(Ks)及 pH、温度的影响，计算了配合物的热力学函数(?G、?H、 2+ 者的 Ks 分别为：柠檬酸钙(CaCit)：Ks=1988；柠檬酸二乙酯钙(CaEt2Cit)：Ks=231。pH 增 大及温度升高有利于配合物的生成，随着 pH 从 4.0 升高至 8.0，体系中 CaCit 的浓度由 0.281 mmol/L 增加到 0.535 mmol/L，CaEt2Cit 的浓度由 0.094 mmol/L 增加到 0.206 mmol/L；随 着温度从 15升高至 40，CaCit 的 Ks 从 327 增加到 2327，CaEt2Cit 的 Ks 从 58 增加到 2+ Et2Cit 作为抗凝剂时能避免使用 Na3Cit 所出现的低钙血症和高钙血症等问题，有望成为一 种潜在的新型抗凝剂。 关键词：离子选择电极法；柠檬酸二乙酯；柠檬酸钠；配合物；稳定常数 中图分类号：O642 Thermodynamic features of diethyl citrate calcium complexes and factors affecting the complex stability Chen Bin1, Ou Yan2, Gui Baosong2, Ouyang Jianming1 (1. Institute of Biomineralization and Lithiasis Research, Jinan University, GuangZhou 510632; 2. Department of Nephrology, the Second Hospital of Xian Jiaotong University, Xian 710004) Abstract: Diethyl citrate (Et2Cit) is a promising new anticoagulant. The stoichiometry of the Et2Cit complex with Ca2+ ions and the stability constant (Ks) were determined using ion-selective electrode; The effect of pH and temperature on complex stability were then discussed; Thermodynamic functions (△G、H 、S) of the complex were also calculated in this study. These results were compared with the sodium citrate (Na3Cit), a current clinical anticoagulant. Our study showed that both Et2Cit and Na3Cit formed complexes with Ca2+ ion at 1:1 ratio. The Ks measured for calcium diethyl citrate (CaEt2Cit) and calcium citrate (CaCit) was 231 and 1988, respectively, at pH 7.4, 37℃. Increasing pH or solution temperature favored the formation of both complexes. As pH increased from 4.0 to 8.0, the concentration of CaEt2Cit rose from 0.094 mol/L to 0.206 mol/L, and CaCit from 0.281 mol/L to 0.535 mol/L, respectively. Increasing temperature from 15 to 40℃ led to a shift of Ks from 58 up to 327 for CaEt2Cit, and 327 up to 2327 for CaCit. The stability of CaEt2Cit was much lower than that of CaCit, Et2Cit is