Sm-EDTMP稳定常数的测定及其在血浆模型中的平衡组分  

Determination of the Stability Constants of Sm-EDTMP and Their Speciation in Plasma Model

作　　者：蒋树斌[1] 陈晓军[1] 罗顺忠[1] 邴文增[1] 王关全[1] 熊晓玲[1] 

机构地区：[1]中国工程物理研究院核物理与化学研究所,四川绵阳621900

出　　处：《核化学与放射化学》2005年第1期47-51,共5页Journal of Nuclear and Radiochemistry

基　　金：中国工程物理研究院科学基金资助项目(20020537)

摘　　要：为了解153 Sm EDTMP 在血液中的平衡组分,采用电位滴定法测定了 EDTMP 的质子化常数和 Sm EDTMP的稳定常数。EDTMP的质子化常数为:lgβ2 =22.69±0.02,lgβ3 =30.54±0.03,lgβ4 =36.93±0.02,lgβ5=42.15±0.01,lgβ6 =45.02±0.03,lgβ7 =46.14±0.02;Sm EDTMP的稳定常数为: lg KSmL=22.62±0.02,lg KSmLH=29.93±0.02,lg KSmLH2 =36.18±0.03。在生理pH条件下,EDTMP主要以LH3 形式存在, Sm EDTMP 主要以 SmLH 形式存在。血浆模型中,在生理 pH 条件下, Sm 主要以带负电荷的SmLH和SmL形式存在,Sm EDTMP通过人体肾脏排泄;在低 pH(pH<6)条件下,以 Sm 柠檬酸组分存在,表明153Sm EDTMP在人体中肝摄取很低。同时,平衡组分中游离 Sm3+ 含量很低,说明 Sm EDTMP有很高的血浆稳定性,不用加入过量配体来防止标记物解离。EDTMP在血浆模型中主要以 LH3 形式存在,没有出现EDTMP的钙配合物组分,说明配体EDTMP不会使患者血钙明显降低。The cumulative protonation constants of ethylenediamine-N,N,N',N'-tetramethene phosphonic acid (EDTMP, LH8) and the stability constants of its Sm(III) complexes are determined by pH-potentiometry at (37.0±0.1)°C. The experimental data are analyzed with the software package Hyperquad 2000. The first protonation constant lg β1=12.90 of EDTMP is taken from literature. The following values are found: lgβ2=22.69±0.02, lgβ3=30.54±0.03, lgβ4=36.93±0.02, lgβ5=42.15±0.01, lgβ6=45.02±0.03, lgβ7=46.14±0.02 for EDTMP, and lgKSmL=22.62±0.02, lgKSmLH=29.93±0.02, lgKSmLH2=36.18±0.03 for Sm-EDTMP. The speciation studies indicate that EDTMP exists principally in the form of LH3, and Sm(III) in the forms of SmLH and SmL at physiological pH. Plasma thermodynamic equilibrium model simulation shows that SmLH and SmL are the predominant species of 153Sm in blood after intravenous injection of 153Sm-EDTMP. The existence of 153Sm as negatively charged 153Sm-EDTMP complexes in blood could explain why the administrated 153Sm-EDTMP is mainly excreted by kidneys. The complexation of Ca2+ by plasma EDTMP is found negligibly small, and lost of blood calcium would not be a problem during the palliative therapy of bone tumor.

关 键 词：^153SM EDTMP 稳定常数 组分 

分 类 号：O615.4[理学—无机化学] TQ463.7[理学—化学]