离子交换分离-石墨炉原子吸收光谱法测定饮用水中痕量铊

Determination of Trace Amount of Thallium in Potable Water by GFAAS with Ion-Exchange Separation

水样经硝酸酸化、蒸发浓缩后,调pH至1.7~2.0;用溴水氧化铊(Ⅰ)为铊(Ⅲ);用D401离子交换树脂分离出铊,而后用石墨炉原子吸收光谱法测定。在pH 1.8附近,铊(Ⅲ)可与砷(Ⅴ)、硼(Ⅲ)、钡(Ⅱ)、铍(Ⅱ)、钙(Ⅱ)、镓(Ⅲ)、钾(Ⅰ)、锂(Ⅰ)、镁(Ⅱ)、锰(Ⅱ)、钠(Ⅰ)、锑(Ⅴ)、硅(Ⅳ)、锶(Ⅱ)、铋(Ⅲ)、铜(Ⅱ)、钛(Ⅳ)和钒(Ⅴ)分离;而铝(Ⅲ)、镉(Ⅱ)、铬(Ⅲ)、铁(Ⅲ)、镍(Ⅱ)、铅(Ⅱ)和锌(Ⅱ)不能与铊完全分离,但一般水样经分离程序后残留下来的这些物质不足以影响对铊的测定。方法的线性范围为25~500pg;测定下限为0.5ng·L^(-1)。方法用于实际样品分析,测定结果与已知值相符,加标回收率在94.0%~110%之间,测定值的相对标准偏差(n=8)在1.9%~15%之间。

The potable water sample was digested with nitric acid,the sample solution was evaporated to a small volume and its acidity was adjusted to 1.7-2.0.Trace amount of Tl（Ⅰ）in the sample solution was oxidized to Tl（Ⅲ）by bromine water,separated on D401ion-exchange resin column and determined by GFAAS.Under the optimum acidity around pH 1.8,Tl（Ⅲ）was separated from arsenic（Ⅴ）,boron（Ⅲ）,barium（Ⅱ）,beryllium（Ⅱ）,calcium（Ⅱ）,gallium（Ⅲ）,potassium（Ⅰ）,lithium（Ⅰ）,magnesium（Ⅱ）,manganese（Ⅱ）,sodium（Ⅰ）,antimony（Ⅴ）,silicon（Ⅳ）,strontium（Ⅱ）,bismuth（Ⅲ）,copper（Ⅱ）,titanium（Ⅳ）,vanadium（Ⅴ）but was not separated completely from aluminium（Ⅲ）,cadmium（Ⅱ）,chromium（Ⅲ）,iron（Ⅲ）,nickel（Ⅱ）,lead（Ⅱ）and zinc（Ⅱ）.However,for most of the water samples,the amount of the above mentioned cations remained after the ion-exchange separation weren′t sufficient to interfere with the determination of thallium.The linearity range for Tl（Ⅲ）was between 25-500 pg,and the limit of quantification was 0.5ng·L^（-1）.The method was applied to the analysis of some substantial samples,giving results consistent with the known values.Recovery found by standard addition method were in the range of 94.0%-110% and RSD′s（n=8）found were in the range of 1.9%-15%.