差分脉冲溶出伏安法测定铜矿中痕量镉

采用预镀汞膜差分脉冲溶出伏安法(DPSV)对铜矿中痕量重金属镉(Cd)进行了测定,讨论了汞膜厚度和双电层状态在测试过程中的变化以及其对测试结果的影响并优化了实验条件.实验结果表明,测试体系中氯离子(Cl-)与汞形成氯化汞和氯化亚汞的共价化合物,在0 V和-0.12 V附近出现明显的氧化峰和还原峰,降低了汞膜的测试灵敏度和使用寿命;汞膜在测试过程中先后经历3个阶段:初始阶段、稳定阶段、衰减阶段;汞膜电极在稳定阶段时具有较高的灵敏度和良好的重现性;汞膜电极在稳定阶段测得Cd在0.1~0.8μg/L,1~10μg/L,10~20μg/L,20~200μg/L,200~2 000μg/L内呈良好的线性关系,相关系数分别为:0.999 4,0.999 7,0.999 8,0.999 4,0.999 3,检测范围为0.1~2 000μg/L,检出下限0.1μg/L;实际测得3个铜矿样品中镉含量分别是2.21,22.69,19.17μg/L,并与原子吸收法相比较,结果良好.

Determination of trace Cadmium in Copper by differential pulse stripping voltammetry

Using a pre-plated mercury mode differential pulse stripping voltammetry carried out the determination of trace amounts of Cd in copper. Cd2 ＋has a clear and stable stripping peak in the near-0. 8 V. Discussed the changes of the mercury film thickness and electric double layer during the test,as well as its influence on the test results and optimized experimental conditions. Experimental results show that chloride can be formed Mercuric chloride and calomel with mercury,and emerged visible redox peaks and reduction peaks in the near 0 V and-0. 2 V,the mercury film has gone through three stages in the testing process： the initial stage,steady state,decay phase; Mercury film electrode in a stable phase measured Cd in 0. 1 ～0. 8 μg / L,1 ～ 10 μg / L,10 ～ 20 μg / L,20 ～ 200 μg / L,200 ～ 2 000 μg / L showed a good linear relationship,Correlation coefficients were： 0. 999 4,0. 999 7,0. 999 8,0. 999 4,0. 999 3,detection range 0. 1 ～ 2 000 μg / L,detection limit 0. 1 μg / L.Actual measured three copper cadmium samples were 2. 21,22. 69,19. 17 μg / L,Compared with the atomic absorption method,it has a good result. The method is simple,fast and high sensitivity in the practical application tests and has practical significance and promotional value.