微晶酚酞分离富集分光光度法测定铊(Ⅲ)

Determination of trace thallium by spectrophotometry after preconcen-tration on microcrystalline phenolphthalein

建立了利用无毒的微晶酚酞作为固相萃取剂分离富集溶液中痕量Tl（Ⅲ）的方法。在H3PO4介质中,Tl（Ⅲ）在水相中与I^-和结晶紫（CV^＋）形成离子缔合物而被微晶酚酞定量吸附,富集后的Tl（Ⅲ）可直接用光度法测定。控制一定的条件,Tl（Ⅲ）能与常见离子Na^＋,K^＋,Al^3＋,Cu^2＋,Pb^2＋,Zn^2＋,Ba^2＋,Mn^2＋,Ca^2＋,Cd^2＋,Fe^2＋等完全分离,且基本不受Cl^-,Br^-,SO4^2-,NO3^-等阴离子的影响。方法可直接应用于环境水样中痕量Tl^3＋的测定,富集倍数可达100倍,回收率95.6%-101.8%,检出限为13 ng/L。

A new method using microcrystalline phenolphthalein as an adsorbent to separate and preconeentrate trace thallium in environmental water samples has been developed. Effects of different parameters, such as the acidity, amounts of salt, amounts of crystal violet （ CV ^＋ ） and Phenolphthalein, temperature, etc on the enrichment yield of TI（Ⅲ） have been investigated. Under certain conditions TI（Ⅲ） was completely separated from Na ^＋, K^ ＋ ,Al^3＋ , Cu^2＋, Pb^2＋ ,Zn^2＋ ,Ba^2＋ ,Mn^2＋ ,Ca^2＋ ,Cd^2＋ ,Fe^2＋ and hardly affected by Cl^- ,Br^- ,SO4^2- ,NO3^ -. Therefore, the aim of separation and preconeentration of trace thallium could be achieved. The proposed method has been applied to the preconcentration and determination of trace Tl（m） in water samples with satisfactory results.