聚乙烯吡啶化学修饰电极预富集-GFAAS测定废水中痕量Cr(VI)和Cr(Ⅲ)的研究

Determination of Trace Amount of Chromium (VI)and Chromium (Ⅲ) in Waste Water By-GFAAS With electrochemical preconcentration at Polyvinyl Pyvidine chemically Modified Electrode

本文研究了用聚乙烯吡啶化学修饰电极预富集——石墨炉原子吸收法测定废水中痕量Cr(Ⅵ)和Cr(Ⅲ)的方法.废水中的痕量Cr(Ⅵ)被富集到经聚乙烯吡啶修饰的钨丝电极上,然后放入石墨杯中进行原子吸收测定“Cr(Ⅲ)在碱性条件下经H_2O_2氧化为Cr(Ⅵ),同法测定在pH为4的HCl介质中,测定的线性范围为1～25ng/m1,对含Cr(Ⅵ)10ng/ml的溶液十次平行测定,相对标准偏差为5.4%,检出限0.4ng/ml,二十多种共存离子不干扰测定.样品测定回收率在94～104%之间.

This paper describes a method for the determination of trace amount of Cr(Ⅵ) and Cr(Ⅲ) in waste water by using graphite furnace AAS with electrochemical preconcentration of polyvinyl pyridine chemically modified electrode.A coiled tungsten wire electrode is modified with a thin film of polyvinyl pyridine.Trace amount of Cr(Ⅵ) in waste water is preconcentrated by the electrode, then is put into a graphite cup for AAS measurement.Cr (Ⅲ) can also been determined after being oxidated into Cr(Ⅵ)by oxydol in a basic condition.In a solution of HCl at pH4 the linear range for the determination is 1～25 ng/ml.The relative standard deviation for ten parallel determinations of a solution containing 10 ng/ml Cr(Ⅵ) is 5.4%.The detection limit is 0.4 ng/l.More than twenty foreign ions do not interfere significantly.The recovery rates are 94～104%.