Flow injection spectrophotometric determination of selenium based on the catalysed reduction of Toluidine Blue in the presence of sulphide ion

Abstract

The flow injection spectrophotometric determination of selenium is described based on its catalytic effect on the reduction of Toluidine Blue by sodium sulphide. After optimisation of the measuring conditions the detection limit is 0.08 µg of selenium(IV) and the linear range is 0.2–2 µg (80-µl injections). The method is suitable for routine analysis; about 35 samples can be injected per hour. The procedure was applied to the determination of selenium in ores and pharmaceutical preparations.