Determination of Traces of Gold III in Water by Metal Furnace Atomic Absorption Spectrophotometry after Adsorption of Gold (III) on the Chitin

Abstract

The natural polymer “ chitin” has the property of being an anion-exchanger in an acidic medium, because the acetylamino groups of chitin are protonated in an acidic medium. The property of chitin was applied to the preconcentration and determination of sub ppb level of Au (III) by adsorption to the chitin as their anionic complex with metal furnace atomic absorption spectrophotometry. Au (III) reacts with anion such as halogenide ion, cyanide ion to form the anionic complex. The adsorption isotherm of Au (III)as their anionic complex on the chitin was known to be fitted by. Freundlich equation. The adsorption quantity of Au (III) as their anionic complex becomes larger in order of the complex, chloro anionic complex, bromo anionic complex, iodo anionic complex, cyano anionic complex. Especially, Au (III) was quantitatively collected as its chloro anionic complex on chitin over the range of pH 2.0 to 4.0. The chitin which adsorbed the Au (III) was separated from the sample solution with a membrane filter and dispersed in pure water. The resulting suspension was introduced directly into the tungsten metal furnace atomizer. The detection limit for Au (III) was 0.05 μg/500 cm³ (S/N ≥ 3). The proposed method was a plied to the determination of trace amounts of Au (III) in several water samples.