Potentiometric determination of silver thiolate formation constants using a Ag2S electrode
Potentiometric determination of silver thiolate formation constants using a Ag2S electrode
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DOI：
10.1023/a:1009699617808
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发表时间：
1999-01-01
影响因子：
1.6
通讯作者：
Kramer, JR
中科院分区：
文献类型：
--
作者：
Adams, NWH;Kramer, JR
通过在恒温、恒定离子强度和pH值的介质中对配体进行滴定，并测量硫化银电极上的电位变化，获得了硫醇银的形成常数。推导出一个非线性方程，由此确定了一级和二级银形成常数β(1)'和β(2)'以及硫化物基团的酸解离常数K - a'。使用蒙特卡罗方法对所导出参数的不确定性进行了总体估计。将该方法与先前关于AgHS°的研究进行了比较。在20℃和0.01m离子强度下，得到了半胱氨酸（logβ(1)'为11.9±0.5，logβ(2)'为15.2±0.4，-log K - a'为7.8±0.1）、谷胱甘肽（logβ(1)'为12.3±0.3，logβ(2)'为14.3±0.8，-log K - a'为8.8±0.3）和3 - 巯基丙酸（logβ(1)'为12.0±0.4，logβ(2)'为14.0±0.4，-log K - a'为10.5±0.3）的结果。
Formation constants for silver thiolates were obtained by titration of the ligand in a constant temperature, ionic strength and pH medium and measuring the potential change at a Ag2S electrode. A non-linear equation was derived from which the first and second silver formation constants, beta(1)' and beta(2)', and the sulfide group acid dissociation constant, K-a', were determined. An overall estimate of the uncertainty in the derived parameters was obtained using a Monte Carlo approach. The procedure was compared to a previous work on AgHS degrees. Log beta(1)', log beta(2)' and -log K-a' results were obtained for cysteine (11.9 +/- 0.5, 15.2 +/- 0.4, 7.8 +/- 0.1), glutathione (12.3 +/- 0.3, 14.3 +/- 0.8, 8.8 +/- 0.3) and 3-mercaptopropanoic acid (12.0+/- 0.4, 14.0 +/- 0.4, 10.5 +/- 0.3) at 20 degrees C and 0.01 m ionic strength.