固体汞合金电极钙黄绿素吸附催化伏安法测定轻稀土  

Determination of light rare earth by calcein adsorptive catalytic voltammetry with solid amalgam alloy electrode

作　　者：魏小平[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：《冶金分析》2008年第12期12-16,共5页Metallurgical Analysis

基　　金：广西自然科学基金(桂科自0679002;0728214);广西教育厅科研基金(桂教科200508135)

摘　　要：采用汞合金电极为工作电极，以铈为轻稀土代表，研究了在双氧水存在下，铈-钙黄绿素体系的吸附平行催化伏安法测定轻稀土。在pH10．3的NH3·H2O-NH4Ac缓冲溶液中，铈-钙黄绿素络合物于-1．42V可产生灵敏还原峰，加入双氧水后峰电流明显增大（约20倍）。导数峰高与Ce（Ⅳ）浓度在0．02～5μg／mL范围内呈线性关系，方法检出限为0．01μg／mL。研究了电流性质及电极反应机理，证明其为络合物吸附催化波。铈与钙黄绿素形成络合比为1：1的络合物，络合物中的钙黄绿素在电极上还原，电极上还原的中间产物被双氧水氧化成原价态，继续参加电极反应，从而形成一种催化循环，使峰电流增大。利用固体汞合金为电极，钙黄绿素络合吸附催化波法可测定稀土球墨铸铁中轻稀土总量，结果同认定值相吻合。Cerium as the representative of light rare earth was determined by adsorptive parallel catalytic voltammetry with solid amalgam alloy electrode as working electrode in cerium-calcein system with hydrogen peroxide. In the buffer solution of NH3 · H2O-NH4Ac at pH10.3, cerium-calcein complex could generate sensitive reducing peak at -1.42 V. The peak current increased significantly after adding hydrogen peroxide （about 20 times）. The height of derivative peak showed linearity with Ce（Ⅳ） in the range of 0.02-5 μg/mL. The detection limit was 0.01 μg/mL. The current property and electrode reaction mechanism were investigated, indicating that it was a complex adsorptive catalytic wave. The complex ratio of cerium and calcein was 1 ： 1. The calcein in complex was reduced on electrode and the intermediate products was oxidized to original state by hydrogen peroxide during continuous electrode reaction to form a catalytic cycle, increasing the peak current. The content of light rare earth in rare earth spheroidal graphite iron could be determined by proposed method. The results were in good agreement with the certified values.

关 键 词：吸附催化伏安法 轻稀土 固体汞合金电极 钙黄绿素 

分 类 号：TG115.3[金属学及工艺—物理冶金]