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本文对不同条件下形成的汞膜进行了显微观察,并与电化学方法结合,研究了玻碳电极上汞膜的形成过程、汞膜形态与其形成条件的关系以及对溶出峰的影响.结果表明:玻碳表面的汞膜是由视直径小于10μm 的微汞滴构成,其分布密度随镀汞电位的负值增加而增加;微汞滴在电析过程中不断长大并相聚成更大一些的微汞滴,在旋转玻碳电极上,汞膜的最大平均厚度不会超过5μm,而适用于溶出分析的范围为0.05～1μm,比文献记载的范围(0.001～10μm)要窄得多;镀汞用的 Hg~(2+)浓度的适用范围为1×10~(-5)～2×10~(-4)M;Hg~(2+)浓度为2×10~(-5)M 时虽经长时间镀汞亦不易产生较大的微汞滴.实验还表明峰高的重现性与电极表面的载汞量有关.还观察到较大的微汞滴在电极表面滑动以致被甩离电极表面的现象,严重时会引起峰高的下降.
In this paper, the mercury films formed under different conditions were observed microscopically and electrochemical methods were combined to study the formation of mercury film on the glassy carbon electrode, the relationship between the morphology of mercury film and its formation conditions and the effect on the dissolution peak.Results The results show that the mercury film on the surface of glassy carbon is composed of micro mercury drop whose diameter is less than 10μm and its distribution density increases as the negative value of mercury plating potential increases. The mercury droplet grows up and coalesces into larger Some micro-mercury droplets, on the rotating glassy carbon electrode, the maximum average thickness of the mercury film does not exceed 5μm, and the range of suitable for the dissolution analysis of 0.05 ~ 1μm, narrower than the documented range (0.001 ~ 10μm) is much narrower The range of Hg 2+ concentration for mercury plating is 1 × 10 -5 -5 × 2 × 10 -4 M and the concentration of Hg 2+ is 2 × 10 -5 ) Is not easy to produce large micro mercury drop even after prolonged mercury plating.The experiments also show that the reproducibility of the peak height is related to the amount of mercury contained on the surface of the electrode.It is also observed that the larger micro mercury drop slides on the electrode surface So that the phenomenon of being rid of the electrode surface, will cause serious decline in peak height.