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    土壤中铅、镉测定的试样预处理方法的改进

    Modification of Method of Sample Pretreatment in the Determination of Lead and Cadmium in Soil

    • 摘要: 作为对GB/T 17140-1997中所列方法的改进,建议用混合酸(VHNO3+VH2O2+VHF=4+2+1)在微波消解仪中消解试样.微波消解的参数也进行了试验并确定了最佳条件,所得试样溶液蒸发至浆状并加盐酸溶解盐类,将试样中的Pb(Ⅱ)、Cd(Ⅱ)以碘化物络阴离子的形式萃取入4-甲基戊酮-2(MIBK)液层中,并在MIBK溶液中用火焰原子吸收光谱法测定铅及镉.试验结果表明:经改进的方法不仅有较高的精密度和准确度,而且操作简便且快速,算得两元素测定结果的相对标准偏差(n=10)均小于5%.测定铅和镉的回收率分别为99.2%和96.4%.

       

      Abstract: As a modification for the method given in GB/T 17140-1997,the pretreatment of soil sample was improved by digesting in an acid mixture of HNO3+H2O2+HF (prepared in the ratio of 4+2+1) and heating in a microwave assisted digestor under specified parameters.The sample solution was evaporated to syrupy consistency and taken up with hydrochloric acid.Lead and cadmium ion in HCl solution were then extracted into 4-methyl-pentanone-2 (MIBK) as their iodide anionic complexes,and determined in MIBK-phase by FAAS.As proved by experimental data,the modified method showed its special features not only in precision and accuracy,but also rapid and convenient in operation.Values of RSD′s (n=10) obtained were less than 5% for both element,and recovery were 99.2% for lead(Ⅱ) and 96.4% for cadmium.

       

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