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应用电位溶出分析法,在0.35M NaNO_3 pH=1.4中能测定Sn(Ⅳ)和Sn(Ⅱ)。当使用溶解的氧为氧化剂(7.9×10~(-5)M),预富集时间为4分钟时,此法的测定灵敏度为1×10~(-9)M。循环伏安法显示,Sn(Ⅱ)→Sn(0)是最主要的还原步骤;而在氧化过程中,Sn(0)→Sn(Ⅱ)是最主要的氧化步骤。进行了各种干扰离子的实验。可以将干扰离子分为两类:(1) 与Sn的氧化电位(—0.45Vvs.Ag/AgCl相同者,能使Sn的过渡时间(或称消失时间)增长。(2) 对Sn呈现氧化作用者,使Sn的过渡时间缩短。当有与Sn(Ⅳ)或Sn(Ⅱ)形成络合物的试剂存在时,例如磷苯三酚和α巯基乙酸,由于形成的络合物吸附在电极表面,能使灵敏度提高三至四个数量级。磷苯三酚及α巯基乙酸存在时的灵敏度分别为1×10~(12)M和1×10~(-13)M。循环伏安法显示存在着这种吸附。利用吸附效应进行电位溶出分析的方法称为吸附电位溶出分析法。测定了若干水样中的微量锡的含量。所得的结果与阳极溶出法和分光光度法相对照。
Potentiometric stripping analysis was used to determine Sn (Ⅳ) and Sn (Ⅱ) in 0.35M NaNO_3 pH = 1.4. When the dissolved oxygen is used as oxidant (7.9 × 10 -5 M) and the pre-enrichment time is 4 minutes, the sensitivity of this method is 1 × 10 -9 M. Cyclic voltammetry shows that Sn (Ⅱ) → Sn (0) is the most important reduction step, and Sn (0) → Sn (Ⅱ) is the most important oxidation step in the oxidation process. Various interference ion experiments were conducted. Interfering ions can be divided into two categories: (1) the same as Sn oxidation potential (-0.45Vvs.Ag / AgCl, can make the transition time of Sn (or disappearance time) increase. (2) the oxidation of Sn , Thereby shortening the transition time of Sn In the presence of a reagent that forms a complex with Sn (IV) or Sn (II) such as pyrogallol and alpha thioglycolic acid, the complex formed is adsorbed on the surface of the electrode , The sensitivity can be improved by three to four orders of magnitude.The sensitivity of pyrogallol and α-thioglycolic acid in the presence of 1 × 10 ~ (12) M and 1 × 10 ~ (-13) M respectively.The cyclic voltammetry This method of adsorption-potential stripping analysis is called adsorption potential stripping analysis, and the content of trace tin in several water samples is determined. The results obtained are in contrast with the anodic stripping and spectrophotometry.