Determination of arsenic or tin in steels by the automated extraction system with a recycled solvent and an improved gravity phase separation column

摘要

An automated on-line solvent extraction system has been developed for the determination of arsenic or tin in steel by electrothermal atomic absorption spectrometry (ET-AAS). It is based on the formation of Asl(3) and Snl(4) in concentrated hydrochloric acid and sulfuric acid media, respectively. They are extracted into benzene and back extracted into water and 0.25 mol dm(-3) sulfuric acid, respectively. An improved gravity phase separator was developed for the recycling of organic solvent used in the automated on-line solvent extraction system. Using the proposed system, arsenic or tin contained in the acid dissolved steel sample solution was automatically extracted and back-extracted. Then, the back-extracted solutions were used for the determination of arsenic or tin by ET-AAS. In the determination of arsenic, 800 mg dm(-3) of cobalt solution had to be used as the matrix modifier to exclude the effect of coexisting substances such as iodide ion. In the determination of tin, 1 000 mg dm(-3) of palladium solution had to be used in the same manner. By this method, a detection limit of As and Sn was 0.2 mug As in the 0.1 mug Fe and 0.1 pg Sn in the 0.05 g Fe.