da Rocha José Roberto Caetano, Ferreira Tiago Luiz, Torresi Roberto Manuel, Bertotti Mauro
Instituto de Química, Universidade de São Paulo, São Paulo, Brazil.
Talanta. 2006 Mar 15;69(1):148-53. doi: 10.1016/j.talanta.2005.09.010. Epub 2005 Oct 10.
Films of non-stoichiometric tungsten oxides have been deposited onto glassy carbon surfaces by electrodeposition from acidic W(VI) solutions and the chemical stability of these oxides was investigated by using the electrochemical quartz crystal microbalance. At these modified surfaces, rotating disc electrode voltammetric experiments indicated that iodate is electrocatalytically reduced in a mass-transport controlled process. The influence of the film thickness on the response to iodate was investigated and the results indicated a linear relationship between catalytic current and film thickness for relatively thin oxide layers. The modified electrode was employed successfully as an amperometric sensor for iodate in a flow injection apparatus. The linear response of the developed method is extended from 5 micromol L(-1) to 5 mmol L(-1) iodate with a limit of detection (signal-to-noise=3) of 1.2 micromol L(-1). The repeatability of the method for 41 injections of a 1 mmol L(-1) iodate solution was 0.8% and the throughput was determined as 123 h(-1). Interference from other oxidant anions such as nitrate and nitrite was not noticeable, whereas bromate and chlorate interfere at slight levels. The method was used in the determination of the iodate content in table salt samples.
通过在酸性W(VI)溶液中进行电沉积，将非化学计量比的氧化钨薄膜沉积在玻碳表面，并使用电化学石英晶体微天平研究了这些氧化物的化学稳定性。在这些修饰表面上，旋转圆盘电极伏安实验表明，碘酸盐在传质控制过程中被电催化还原。研究了膜厚度对碘酸盐响应的影响，结果表明，对于相对较薄的氧化层，催化电流与膜厚度之间存在线性关系。该修饰电极成功用作流动注射装置中碘酸盐的安培传感器。所开发方法的线性响应范围为5 μmol L(-1)至5 mmol L(-1)碘酸盐，检测限（信噪比=3）为1.2 μmol L(-1)。对1 mmol L(-1)碘酸盐溶液进行41次进样的方法重复性为0.8%，通量测定为123 h(-1)。其他氧化阴离子如硝酸盐和亚硝酸盐的干扰不明显，而溴酸盐和氯酸盐有轻微干扰。该方法用于测定食盐样品中的碘酸盐含量。
