氧化铱膜修饰微电极的制备及痕量砷(Ⅲ)测定  

Electrocatalytic Determination of Ultratrace Amounts of Arsenic(Ⅲ) at Iridium Oxide Film Modified Microelectrode

作　　者：杜亚琳[1] 李建平[1] 

机构地区：[1]桂林工学院材料与化学工程系,广西桂林541004

出　　处：《分析测试学报》2007年第3期397-400,共4页Journal of Instrumental Analysis

基　　金：广西高校百名中青年骨干教师资助计划项目(桂教人[2005]64号);桂林工学院博士基金资助项目

摘　　要：通过在铱丝尖端电沉积氧化铱，制成氧化铱膜修饰微电极，研究了其电化学性质，测定了电极反应的动力学常数，电极反应的电子转移数为1，电子转移系数0．55，表观电子传递速率为0．18^-1。在pH 4．5的磷酸缓冲溶液中，氧化铱膜修饰微电极对As（Ⅲ）的氧化有明显催化作用，可用于痕量As（Ⅲ）的测定，氧化峰电位为0．62V。峰电流与As（Ⅲ）的浓度在5×10^-8．8×10^-5moL／L范围呈良好的线性关系，检出限5×10^-9mol／L，响应时间小于1s。该电极制作简单，稳定性和重复性好，已用于实际样品分析。Iridium metal wire modified by electrodeposition from iridium oxide have been developed for detection of arsenic （ Ⅲ ）. Cyclic vohammetry was used to deposit iridium oxide on the tip of iridium metal wire in 0. 5 mol/L H2SO4 solution. The proposed method allows excellent control of the deposited amount and the rate of the iridium oxide film growth. The iridium oxide film modified microelectrodes showed excellent electrocatalytic activity toward oxidation arsenic （ Ⅲ ）. In phosphate buffer solution （ pH 4. 5） , an oxide peak was obtained in arsenic （ Ⅲ ） solution with an oxidation peak at 0. 62 V. The electron transfer number（n） , electron transfer coefficient and electron-transfer rate constant（ Ks ） were 1, 0. 55, and 0. 1 s^-1 , respectively at the scan rate of 10 mV/s. The peak current exhibited a good linear range from 5 × 10-8 ^- 8 × 10^-5 mol/L with a correlation coefficient of 0. 999 8. The iridium oxide modified microelectrode is easy to prepare with good reproducibility and satisfactory for quantitative determination. The advantageous properties of this iridium oxide film modified microelectrode for arsenic determination are its inherent stability, excellent catalytic activity, high sensitivity and simplicity.

关 键 词：氧化铱 修饰微电极 砷(Ⅲ) 

分 类 号：O657.1[理学—分析化学] O613.63[理学—化学]