Flotation of sub-microgram amounts of arsenic coprecipitated with iron (III) hydroxide from natural waters and determination of arsenic by atomic-absorption spectrophotometry following hydride generation

Abstract

A method is described for the flotation and determination of sub-microgram levels of arsenic in water. A sub-microgram amount of arsenic (III, V) in a 500-ml sample of water is coprecipitated with iron (III) hydroxide at pH 8–9. The precipitate is floated with the aid of sodium oleate and small air bubbles, then separated and dissolved in 5 M hydrochloric acid, and finally the arsenic content is determined by generation of arsine using sodium tetrahydroborate (III) as a reductant and atomic-absorption spectrophotometry with a long absorption cell (60 × 1.2 cm i.d.). This separation technique has been successfully applied to the determination of sub-microgram amounts of arsenic (III, V) in natural waters.