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    共沉淀分离富集-石墨炉原子吸收光谱法测定水中痕量铅和镉

    GF-AAS Determination of Trace Amounts of Lead and Cadmium in Water After Separation and Enrichment by Co-precipitation

    • 摘要: 水样中痕量铅(Ⅱ)及镉(Ⅱ)通过用2-巯基苯并噻唑与铜(Ⅱ)所生成的沉淀作载体从pH 9的氨性缓冲溶液中共沉淀.用离心法将沉淀从溶液中分离后溶于稀硝酸中,按所选定的分析条件用石墨炉原子吸收光谱法测定其中两元素的含量.为使痕量的铅(Ⅱ)和镉(Ⅱ)例如2.0 μg铅(Ⅱ)及0.1 μg镉(Ⅱ)分离完全,需加入1 mg铜(Ⅱ)所生成的MBT-Cu沉淀作为载体;此时,两元素的回收率均达90%以上.在富集倍数为100的条件下,铅(Ⅱ)及镉(Ⅱ)的检出限(3s/b)依次为0.015 μg·L-1及0.003 μg·L-1.应用此方法分离、富集并测定了3种水样中痕量铅(Ⅱ)及镉(Ⅱ),测定值的相对标准偏差依次为5.1%及4.7%.

       

      Abstract: Trace amounts of Pb(Ⅱ) and Cd(Ⅱ) in water sample were co-precipitated by using the precipitate of Cu(Ⅱ) chelate with 2-mercaptobenzothiazole MBT-Cu(Ⅱ) in short as carrier from solution buffered at pH 9 with ammoniacal buffer.The precipitate was separated from the solution by centrifugation and dissolved in dilute HNO3,which was then used for GF-AAS determination of lead and cadmium under prescribed conditions.For coprecipitation of trace amounts of Pb(Ⅱ) and Cd(Ⅱ),e.g.,2.0 μg of Pb(Ⅱ) and 0.1 μg of Cd(Ⅱ),1 mg of Cu(Ⅱ) as MBT-Cu(Ⅱ) precipitate was necessary to be added as carrier,and values of recovery for both the elements attained were over 90%.Under the condition that the multiple of enrichment was taken as 100,the detection limits (3s/b) attained for Pb(Ⅱ) and Cd(Ⅱ) were 0.015 μg·L-1 and 0.003 μg·L-1 respectively.Values of RSD′s (n=7) found for the method,when applied to the analysis of 3 water samples,were 5.1% for Pb(Ⅱ) and 4.7% for Cd(Ⅱ).

       

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