On-lineヨウ化物抽出/原子吸光法およびモリブドヒ酸青吸光光度FIA法による鉄鋼中のヒ素の定量

抄録

An automated on-line solvent extraction system has been developed for the determination of arsenic in steels by electrothermal atomic absorption spectrometry (ET-AAS) or flow injection analysis (FIA) based on the molybdenum blue reaction. It is based on the reaction of As(III) with iodide ion in the concentrated hydrochloric acid medium to produce AsI₃, which is extracted into benzene and back-extracted into water. Because of an easy separation of water phase and benzene phase, a gravitational phase separator column was used in the automated on-line solvent extraction system. It was not utilized a membrane type phase separator so that the proposed automated on-line solvent extraction system was obtained with long-term stability, low solvent consumption and high reproducibility. Using the proposed automated on-line solvent extraction system, arsenic contained in the acid decomposed steel sample solution was automatically extracted into the benzene phase and it was back-extracted into the water phase. Then, the back-extracted water phase was used for the determination of arsenic by ET-AAS or FIA. When the ET-AAS method used for the determination of arsenic, 800 mg dm^-3 of cobalt solution had to use as the matrix modifier to remove an effect of coexisted substances such as iodide ion. In this method, a determination limit of As is 0.2μg in the 0.1g of steel sample. When the FIA method used for the determination of arsenic, a determination limit of As was 1.0μg in the 0.1g of steel sample.