桑色素修饰碳糊电极吸附溶出伏安法测定人尿中痕量铅

DETERMINATION OF TRACE AMOUNTS OF LEAD IN HUMAN URINE BY ADSORPTIVE-STRIPPING VOLTAMMETRY WITH PASTE CARBON ELECTRODE CHEMICALLY MODIFIED WITH MORIN

制作了用桑色素作修饰剂的碳糊修饰电极 ,利用该电极为工作电极 ,建立了测定痕量铅的新方法。在甲酸钠 盐酸缓冲溶液 (pH 4 .9)中 ,在 - 0 .10V(vs .SCE)下搅拌富集 ,铅 (Ⅱ )与化学修饰碳糊电极表面的桑色素形成电活性络合物而吸附富集于电极表面 ,经 - 0 .85V(vs.SCE)静止还原后 ,阳极化线性扫描 ,在 - 0 .4 3V(vs .SCE)获得一灵敏的二次导数溶出峰。在最佳条件下分别富集 360s和 180s ,其二次导数峰电流与铅 (Ⅱ )浓度分别在 5 .0× 10 - 9～ 1.0× 10 - 7mol·L- 1和 2 0×10 - 8～ 1.0× 10 - 6 mol·L- 1两个范围内呈良好的线性关系 ,富集 6min ,检出限可达 1.0× 10 - 9mol·L- 1(S/N =3)。同时 ,探讨了电极反应机理。方法应用于尿铅测定 。

A new paste carbon electrode chemically modified with morin was fabricated and used as the working electrode in the adsorptive stripping voltammetric determination of traces of lead in human urine. An electroactive complex was formed between Pb(Ⅱ) ion and morin which was modified on the surface of the electrode, and the complex was adsorbed and concentrated on the electrode in a sodium formate HCl buffer medium of pH 4.9 and at -0.10V ( vs. SCE) under stirring. After standing for 40s at -0.85V ( vs. SCE), the lead(Ⅱ) accumulated on the electrode was reduced, upon anodic linear scanning, a sensitive, second derivative stripping peak was observed at -0.43V ( vs. SCE). Linear relationships were obtained in the concentration ranges 5×10 -9 ～1.0×10 -7 mol·L -1 and 2×10 -8 ～1.0×10 -6 mol·L -1 of lead(Ⅱ) for preconcentration for 360s and 180s respectively. A limit of detection of 1.0×10 -9 mol·L -1 ( S/N =3) was obtained when preconcentrated for 360s. A brief discussion was also given on the mechanism of the electrode reaction. Satisfactory results were obtained in the analysis of human urine.