原子吸收光谱法间接研究碱式胱氨酸锌的配合反应

在研究原子吸收间接测定胱氨酸(Cystine, Cys-Cys)时，发现胱氨酸与锌离子在碱性条件下能形成可溶性碱式胱氨酸锌配合物，并在pH 9.4左右时达到最大浓度，经编程计算不同pH下的胱氨酸和锌离子的各种存在形式和分析了拟合分布图，指出在pH 9.4左右时，所形成的可溶性碱式胱氨酸锌配合物是由显电中性的Cys-Cys+-,-1价的Cys-Cys-和-2价的Cys-Cys2-,这三种胱氨酸基同时均可以与Zn(OH)₂配位形成三种可溶性碱式胱氨酸锌配合物，其分子式为(COO-)CH(NH+₃)CH₂S—SCH₂CH(NH+₃)COO-]Zn(OH)₂, (COO-)CH(NH+₃)CH₂S—SCH₂CH(NH₂)COO-]Zn(OH)₂,(COO-)CH(NH₂)CH₂S—SCH₂CH(NH₂)COO-]Zn(OH)₂。理论计算分析的结果与实验数据得到了很好的吻合，并确定了硫化锌法原子吸收间接测定胱氨酸时的配合物反应机理。

Indirect Study of Zinc-Cystine Complex Reaction by FAAS

Each state of cystine and zinc ion in aqueous solution under different pH conditions was calculated by computer, and the scatter diagram was given. Under the influence of solution pH, the mechanism of complex reaction in indirectly determining cystine by flame atomic absorption spectrometry with ZnS was studied. The soluble complex ion is composed of 0 valence cystine Cys-Cys+/-, -1 valence cystine Cys-Cys+/- and -2 valence cystine Cys-Cys(2-) with Zn(OH)2. The theoretical analysis from computing and scatter diagram dovetail very well with the data determined from the experiments. The structure of soluble zinc-cystine complex ion is, (COO-) CH (NH3+) CH2S-SCH2 CH (NH3+) COO-] Zn (OH)2, (COO-) CH (NH3+) CH2S-SCH2CH(NH2)COO-]Zn(OH)2 and (COO-)CH(NH2)CH2S-SCH2CH(NH2)COO-]Zn(OH)2.