串联电解池分步预富集溶出伏安法测定血铅量
ASVA Determination of Lead in Blood with Stepwise Pre-enrichment Through Tandem Electrolytic Cells
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摘要: 将两薄层电解池串联在一起,在前池中装置一大面积汞膜玻碳电极(278.5 mm2),在后池中装置一小面积汞膜玻碳电极(3.14 mm2),血样稀释10倍后作为分析样品。样品溶液先在大面积电极上富集并溶出,再在小面积电极上第二次富集后,随即以300 mV·s-1速率进行电位扫描,并记录阳极溶出伏安图,方法中加入镉(Ⅱ)作为内标。测得溶出峰高的一阶导数值与铅(Ⅱ)的质量浓度在140 μg·L-1范围内呈线性关系,其检出限(3s/k)为0.41 μg·L-1(富集时间20 s)。应用此方法分析了一血样,并以此样品作基体,在6个浓度水平上加入铅(Ⅱ)标准溶液进行回收试验,测得回收率在108.6%~111.6%之间。Abstract: Two thin layer electrolytic cells, with a large area Hg-film GCE (278.5 mm2) in the former cell and a small area Hg-film GCE (3.14 mm2) in the later cell, were linked in tandem and used for enrichment of Pb2+ from blood sample, which was obtained by diluting the blood for 10 times. Lead(Ⅱ) in the sample was enriched on the large area electrode in the 1st cell and thence stripped from the electrode, and enriched again on the small area electrode in the 2nd cell, and then the anodic stripping voltammogram was recorded by potential scanning at a rate of 300 mV·s-1. Cadmium(Ⅱ) was used as internal standard. Linear relationship between values of 1st derivative of peak height and mass concentration of Pb2+ was obtained in the range within 140 μg·L-1, and the detection limit (3s/k) found was 0.41 μg·L-1 (time of enrichment: 20 s). A blood sample was analyzed by this method, and recovery was tested by standard addition method at 6 concentration levels, giving values of recovery in the range of 108.6%-111.6%.