碳糊修饰电极的研制及其吸附伏安法测定痕量锑的研究

【作者】 夏姣云；

【导师】 严规有；

【作者基本信息】 中南大学 ， 分析化学， 2003， 硕士

【摘要】 本论文借助电化学手段，研制出了新型修饰碳糊电极，代替传统的滴汞电极和其它固体电极，同时研究测定了Sb（Ⅲ）的吸附伏安法的条件及其电极反应机理。首次提出了不经任何分离，直接、快速测定复杂锌料液中痕量锑的电化学方法，实现了有关生产过程中锑元素的快速工艺控制分析，此外用此法测定了生物样中的痕量锑，也获得满意结果。 从大量的条件试验中得出：溴邻苯三酚红（BPR）修饰的碳糊电极具有良好的重现性和较长的使用寿命；以邻苯二甲酸氢钾—盐酸和CuCl混合液（pH2.5）为富集介质，以0.1mol／LH₂SO₄溶液为溶出介质，于+0.0v（vs．SCE）处搅拌富集2.0min，-0.4v处静止还原30s，在-0.2～+0.3v范围内，于+0.1v左右出现一灵敏的极谱峰；在实验优化的条件下，峰高与Sb（Ⅲ）浓度在8.0×10^-9～2.0×10^-7mol／L范围内呈线性关系，检出限为2.0×10^-9mol／L；机理研究试验表明，络合物中BPR：Sb（Ⅲ）=1：1，电极反应为不可逆过程，其中电子转移数为3，质子转移数为2。 利用CuCl盐酸溶液中的Cu⁺具有还原性，还原Sb（Ⅴ）为Sb（Ⅲ），测定总含量Sb。考虑到湿法炼锌料液中成分的多变性，干扰因素的复杂性和积累效应，提出了以标准加入定容计算法消除共存离子积累效应和试液组成及其浓度较大变化所引起的误差。与传统的标准加入法比较，新方法具有公式模型简单，不要求空白值为零以及不受标准溶液浓度和所用体积严格限制的优越性。 整个实验过程所用试剂无毒、来源广、成本低；操作过程方便、快速（分析总时间为8.0min）、无特殊环境要求；准确度和灵敏度高。该法运用于锌电解料液中痕量锑测定，可用于现场工艺控制快速分析。同时，此法也成功地运用于生物样中痕量锑的测定，为猪肝、猪肾中测定痕量锑提供了一种新的可靠、方便、快速的电分析方法。更多还原

【Abstract】 A new chemically modified carbon paste electrode has been developed to replace drop mercury and other solid electrodes by electrochemical means. At the same time, the conditional tests of adsorptive stripping voltammetry as well as the electrode reaction mechanism of Sb(III) have been determined. For the first time, a highly sensitive adsorptive stripping voltammetry method which does not need any pretreatment for the direct and rapid determination of traces of Sb(III) in the complex solutions has been advanced. The rapid process control analysis of Sb in relevant production has been realized. In addition, the traces of Sb in the biosamples have been advanced by this method with satisfactory results.The conclusions obtained from lots of condition experiments are as follows: The modified carbon paste electrode with bromopyrograll red has favorable repeatability and longevity of service. An electroactive complex of Sb(III) with BPR is formed and accumulated on the surface of the electrode in a stirring biphthalate of potassium (KHP)-HCl and CuCl solutions(pH=2.5) at 0.0v(vs.SCE) for 2 minute. After it is reduced at -0.4v for 30s without stirring, the voltammogram is then recorded by applying an anodizing scan from -0.2v to +0.3v at 250mv/s, and the second derivative peak current is obtained at +0.1v. Under the optimal conditions, linear relationship between the second derivative peak current and Sb(III) concentration is obtained in the range of 8.0 X 10-9~2.0 X 10-7mol/L,and the determination limit is 2.0 X 10-9mol/L . The study on the electrode reaction mechanism shows that the transfered number of electrons is 3, and the transfered number of protons is 2. The electrode reaction is irreversible, and the composition of electroactive complex is BPR:Sb(III)=1:1.With the reducibility of Cu+ of CuCl to reduce Sb(V) to Sb(III), total amounts of antimony is determinated. Regarding the variability of the components in the solutions of zinc by wet process, the complexity of the interference factors, and the accumulation effect, the constant-volume -standard- addition -calculation method is applied for eliminating the errorsarising from the accumulation effect of the coexistence ions and the larger changes of the sample components and their concentrations. Compared with the traditional- standard- addition - method, the constant- volume -standard-addition -calculation method does not need zero blank value, and is not be severely limited by the concentration and volume of the standard solution, and has simple models.All the reagents are innocuous, low-cost and easy to be obtained.The method is convenient to operate with high sensitivity, selectivity and rapidity. It has been successfully applied to the determination of traces of Sb in the solution of zinc electrolyte, it is also a new electroanalysis method to determinate the traces of Sb in the pork livers and the pork kidneys.更多还原