Locatelli C, Fagioli F, Bighi C, Garai T
Department of Chemistry, University of Ferrara, Via L. Borsari 46, 44100 Ferrara, Italy.
Talanta. 1986 Mar;33(3):243-7. doi: 10.1016/0039-9140(86)80058-3.
Second-harmonic alternating-current voltammetry can be used for the sequential determination of two electroactive species having very similar half-wave potentials (deltaE(1 2 ) < 50 mV). Since the concentrations of such metals in samples of special interest are often at trace levels, for their determination second-harmonic a.c. voltammetry (extremely selective but not sufficiently sensitive) can usefully be combined with the anodic stripping method, which has a very high analytical sensitivity. The determination of tin and lead as well as of indium and cadmium in 1M hydrochloric acid is described. The half-wave potentials are only 35 and 45 mV apart, respectively, for these systems. A three-electrode cell was used with a long-lasting sessile-drop mercury electrode as the working electrode, with a drop-time of 240-300 sec. The detection limit was found to be 10(-8)M for all four elements studied. The precision expressed as the relative standard deviation was 2-3% and the relative error was 1-2%.
二次谐波交流伏安法可用于顺序测定两种半波电位非常接近（ΔE(1/2) < 50 mV）的电活性物质。由于在特别感兴趣的样品中，此类金属的浓度通常处于痕量水平，因此为了测定这些金属，可将极具选择性但灵敏度不足的二次谐波交流伏安法与具有很高分析灵敏度的阳极溶出法有效结合。本文描述了在1M盐酸中锡和铅以及铟和镉的测定。对于这些体系，其半波电位分别仅相差35和45 mV。使用三电极池，以持久悬汞电极作为工作电极，滴汞时间为240 - 300秒。研究发现，所有四种元素的检测限均为10^(-8)M。以相对标准偏差表示的精密度为2 - 3%，相对误差为1 - 2%。
