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    铋膜电极溶出伏安法测定食品中痕量重金属

    A Bismuth Film Electrode for Electrochemical Stripping Voltammetric Determination of Trace Heavy Metals in Food

    • 摘要: 以铋膜电极为工作电极,采用微分脉冲阳极溶出伏安法直接测定食品样品中痕量铅、镉和锌.在富集电位-1.4 V,富集时间180 s,铋膜质量浓度150 μg·L-1的条件下,铋膜电极对铅、镉和锌的氧化溶出具有良好的电化学响应.铅(Ⅱ)、镉(Ⅱ)和锌(Ⅱ)的质量浓度在5.0~40 μg·L-1的范围内与其阳极溶出峰电流呈线性关系,铅(Ⅱ)、镉(Ⅱ)和锌(Ⅱ)的检出限(3S/N)分别为0.80,0.65,0.58 μg·L-1.对25 μg·L-1铅(Ⅱ)、镉(Ⅱ)和锌(Ⅱ)溶液用铋膜电极连续测定15次,相对标准偏差分别为6.2%,5.1%,7.1%.方法应用于食品中痕量重金属的测定,测定结果与石墨炉原子吸收光谱法的测定值相符.

       

      Abstract: A bismuth film electrode (BFE) was used as working electrode. Differential pulse anodic stripping voltammetry was applied to the determination of trace amounts of zinc,cadmium,and lead in food samples. Under conditions of enrichment potential of -1.4 V,enrichment time of 180 s,and bismuth film concentration of 150 μg·L-1,BFE exhibited good electrochemical response to oxidation and stripping of zinc,cadmium,and lead. Linear relationships between anodic stripping peak current and mass concentration of zinc(Ⅱ),cadmium(Ⅱ),and lead(Ⅱ) were in the same range of 5.0-40 μg·L-1,with detection limits (3S/N) of 0.80,0.65,0.58 μg·L-1 for zinc(Ⅱ),cadmium(Ⅱ),and lead(Ⅱ) respectively. Precision of the method was tested at concentrations of 25 μg·L-1 zinc(Ⅱ),cadmium(Ⅱ),and lead(Ⅱ) solution for 15 duplicates with BFE,values of RSD were 6.2%,5.1%,and 7.1%,respectively. The proposed method was applied to the determination of trace heavy metals in food,giving results in agreement with values obtained by GFAAS method.

       

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