A thermodynamic equilibrium models consisted of multi-metal ion and low molecular-weight ligands has been constructed to study the speciation of Pu4+ in human blood plasma and the influences of total concentration of DTPA、CO3 2-and Citrate3- on the speciation. Computer simulation indicated that low concentration of plutonium in plasma fluid with Pu(OH)4(aq)species accumula-ted in liver. Pu4+ form precipitation is difficult to eliminate from the body under the high concentration of plutonium in plasma flu-ids. At the concentrations of DTPA was 2. 5 × 10-5 mol·L-1 , the species of plutonium mainly as negatively charged [ Pu ( OH ) DT-PA]2- and maintain stable. The speciation was at first calculated at pH 5. 0,with the increase of concentration of[Citrate3-],the major species of Pu4+ as[ PuCitrate2 ] 2-and[ PuCitrate]+ which were excreted easily from body. In blood plasma Pu4+ combined with Ca2+、Mg2+ to form[CaHDTPA]2-、[Ca2DTPA]-、[CaDTPA]3-、[MgHDTPA]2-、[MgDTPA]3- when[DTPA]at 4.6×10-5mol· L-1 ,which excrete Pu(Ⅳ) and produce toxic side effects on bone at the same time.%建立了由多种金属离子和小分子配体组成的多相人体血浆热力学平衡模型。模拟研究了Pu4+在血浆的形态分布及二乙三胺五乙酸( DTPA)和CO32-、Citrate3-浓度对细胞液中Pu4+形态分布的影响。血浆中的低浓度Pu(Ⅳ)易以Pu(OH)4(aq)的形态蓄积在肝脏中，钚浓度升高则形成沉淀Pu(OH)4(s)难以排出。在[DTPA]=2．5×10-5mol·L-1时，血浆中水溶性小分子[Pu(OH)DTPA]2-含量达到最高并保持稳定。酸性条件下随着[ Citrate3-]的升高，血浆中Pu4+与Citrate3-结合形成可溶性的[ PuCitrate2]2-和[ PuCitrate]+离子化合物。[DTPA]>4．6×10-5mol·L-1时，血浆中的 DTPA以与 Ca2+、Mg2+结合的[CaHDTPA]2-、[Ca2DTPA]-、[CaDT-PA]3-、[ MgHDTPA]2-、[ MgDTPA]3-小分子结合态为主。
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