痕量铅在草酸修饰电极上阳极溶出伏安的研究

本文对草酸修饰电极的制作、痕量铅在草酸修饰电极上的反应机理和电化学特性作了研究。采用阳极溶出伏安法,测定铅的灵敏度比玻碳电极提高7.5倍,在1.0～15.0ng·/mL铅浓度范围内溶出峰高与铅浓度呈良好的线性关系。连续测定12次变异系数为3.0％。利用草酸修饰电极对人尿中痕量铅进行了测定,结果良好。

Study on Anodic Stripping Voltammetry of Trace Lead at Oxalic Acid Modified Electrode

In this paper, the preparation of oxalic acid modified electrode, reaction mechanism and electrochemical characteristics of trace lead on the electrode arereported. The Si(CH2 ) 3NHCCOH group was covalently bonded to glass carbonelectrode surface through chemical reaction. The group could form stable complex with lead in solution and increase the deposition amount of lead on the electrode surface with electrochemical reaction. The behavior of the lead at electrode was investigated by anodic stripping voltammetry in following conditions: 15ng/mL of lead in HAc-NaAc system was preconcentrated at a controlled potential of -0.90 V(vs,SCE) for 2 min, then followed by scanning till -0.10 V(vs, SCE). The anodic stripping voltammograms showed an increase of current at about -0.54V (vs,SCE). Its sensitivity was 7.5 times highter than that of normal glass carbon electrode. The peak height is linearly related to the concentration of lead in the range of 1.0-15.0ng/mL. The relative standard deviation for twelve parallel determinations is 3%. The lead in urine was determined by oxalic acid modified electrode with satisfactory results.