4-(3-吡啶基)-2-巯基咪唑修饰碳糊电极的研制及微量铜的测定

Development of 4-(3-pyridyl)-2-mercaptoimidazole modified carbon paste electrode and application to determination of micro copper

用化合物4-（3-吡啶基）-2-巯基咪唑（PMI）修饰碳粉制备了化学修饰碳糊电极，基于该氮杂环巯基化合物对Cu^2＋络合的选择性，Cu^2＋可富集于该电极表面。修饰电极经富集后再于-0．4V还原20S，阳极化扫描，在0．1V左右可以获得灵敏的铜阳极溶出峰。其二次导数峰电流与Cu^2＋在5．0×10^-5～2．0×10^-5mol／L浓度范围内呈线性关系，检出限可达2．0×10^-9mol／L（S／N=3）。采用本法不经过预分离，对成分复杂的阳极泥和铝合金等样品中的铜可进行直接测定。

The carbon paste electrode was prepared from powdered carbon which was chemically modified by 4-（3-pyridyl）-2-mercaptoimidazole （PMI）. On the basis of the eomplexing selectivity of this nitrogen-bearing heterocyclic mercapto compound, Cu^2＋ could be enriched on the surface of electrode. After enrichment, the modified electrode was reduced for 20 s at --0.4 V. By polarography, the sensitive anodic stripping peaks of copper could be obtained near 0. 1 V. Its second derivative peak current showed good linear relationship with Cu^2＋ in the range of 5.0 × 10^-9-2.0 × 10^-5 mol/L and the detection limit was up to 2.0×10^-9 mol/L （S/N=3）. The copper in anode mud and aluminium alloy samples with complicated components could be directly determined by this method without pre--separation.