原子吸收光谱间接测定碱式胱氨酸锌配合物的稳定常数

利用硫化锌法火焰原子吸收间接测定胱氨酸(Cystine,Cys-Cys)。在碱性条件下,胱氨酸能与硫化锌悬浮液反应生成可溶性碱式胱氨酸锌配位化合物,在pH9·40时达到最大浓度,原子吸收光谱法测定了最大浓度时的配合物含量,并对碱式胱氨酸锌稳定常数进行了测定和理论计算。碱式胱氨酸锌的稳定常数平均值β稳为9·916×1032,其logβ稳=32·996。表明原子吸收光谱不仅可用于微量元素的测定和有机化合物的间接测定,同时也可进行配合离子的物理形态、物理常数的研究和测定。

Indirect Determination of Stability Constant of Zinc Cystine Chelate by Flame Atomic Absorption Spectrometry with ZnS

Cystine was indirectly determined by flame atomic absorption spectrometry with ZnS. Base on the determination mechanism, the composition of complex, the complex balance reaction of soluble zinc ion, which formed in the determination of cystine by FAAS, and the stability constant of complex balance were discussed in the present paper. Under the alkalescent conditions, cystine (Cys-Cys) can react with zinc sulfide suspension solution to form a soluble complex or chelate of zinc cystine. The maximum concentration was reached at pH 9.4 and the quantity of the chelate was determined by flame atomic absorption spectrometry with zinc sulfide. The stability constants of the complex compound of zinc cystine were studied successfully, after the numeric measurements and theoretical investigations under the best-optimized acidity for determination. In conclusion, at the best optimized acidity pH 9.4, the stability constant of alkalescent zinc cystine is between 9. 542 x 10(32) and 10.353 x 10(32), the average value is betaw = 9.916 x 10(32), and log betaw = 32.996. The standard deviation is 0.301 x 10(32). It is shown that the atomic absorption spectrometry can be used not only for the determination of trace elements and the indirect determination of organic compound, but also for the study of physical configuration and the determination of physical constant of complex ion.