チオシアン酸アンモニウムを用いる鉄マトリックスの曇点抽出と鉄鋼微量成分分析への応用 Removal of the Iron Matrix by Cloud-Point Extraction with Ammonium Thiocyanate for the Analysis of Iron Metals

To an iron sample solution were added ammonium thiocyanate, ethylenediaminetetraacetic acid, and polyoxyethylene-4-nonylphenoxy ether (nonionic surfactant, average number of ethylene oxides 7.5). The nonionic surfactant was segregated from the solution by heating at 80°C. The thiocyanato complex of iron(III) was nearly completely collected in the surfactant phase, leaving trace elements [e.g., Mn(II), Ni(II), and Bi(III)] in the aqueous phase. The trace elements were determined by graphite-furnace atomic absorption spectrometry. The proposed method was successfully applied to the analysis of high-purity iron.