离子液体[Bmim]PF_6萃取-火焰原子吸收法测定水中痕量镉

Determination of Trace Cadmium in Water by Flame Atomic Absorption Spectrometry/with Ionic Liquid Extraction

1引言 化学工业排放的废水含有大量金属镉，对环境产生严重危害，因而环境水样中痕量镉的准确测定具有重要意义。目前，常用原子吸收光谱法[1]测定痕量的镉，但由于环境水样中镉的含量低且样品复杂，为了提高分析方法的灵敏度和选择性，样品的预分离与富集至关重要。液一液萃取是一种常用的预分离与富集方法，但常用有机溶剂作萃取剂，易带来二次污染。离子液体是一种无毒、无污染、不挥发的“绿色溶剂”[2]，具有安全、高效、环保等优点[3]，已萃取分离了多种金属离子[4,5]。本实验以双硫腙（H2Dz）为螯合剂，以离子液体1-丁基-3-甲基咪唑六氟磷酸盐（[Bmim]PF6）为萃取剂。用火焰原子吸收光谱法（FAAS）测定了离子液体相中的Cd，建立了痕量Cd的分离与分析方法，并应用于环境水样的分析。

A novel method for the separation and determination of trace cadmium in environmental water sample by flame atomic absorption spectrometry （FAAS） with ionic liquid extraction was proposed. When the acidity of the solvent was pH 8, ionic liquid 1 butyl-3 methylimi dazolium hexafluorophosphate （EBmim]PF6） was used as extractant, dithizone as the chelant, the sample was extracted for 3 min and determined by FAAS. The research result indicated that under optimum conditions, there was favorable linearity relation between 0.15 and 58.2μg/L, detection limit （38） was 0. 095μg/L （n=11）. The recovery of this method was in the range of 90.0%-108.0%, the relative standard deviation is less than 5.8% for the analysis of practical sample.