A sensitive and selective method for determination of gold(III) based on electrothermal atomic absorption spectrometry in combination with dispersive liquid-liquid microextraction using dicyclohexylamine.

A combined method with dispersive liquid-liquid microextraction (DLLME) and electrothermal atomic absorption spectrometry (ETAAS) has been developed for determining gold(III). Dicyclohexylamine, a new extractant for gold(III), showed excellent performance in DLLME. Acetone was indispensable to the quantitative extraction of gold(III), contributing to decrease in hydration, decrease in the difference in the dielectric constants between the supernatant phase and the sedimented phase, and dissolution of a part of chloroform as an extraction solvent to the supernatant phase as well as improvement of dipersibility. In DLLME using a mixture of 1.0mL of acetone and 100microL of chloroform containing 50mmolL(-1) of dicyclohexylamine, gold(III) could be extracted selectively and effectively from 8mL of a sample solution in the presence of iron(III), cobalt(II), nickel(II), copper(II), palladium(II), and platinum(IV) at pH 1. The extracted gold(III) was determinable by ETAAS; the detection limit was 0.002microgL(-1) (three times the standard deviation of the blank values, n=8) as a gold(III) concentration in 8mL of sample solution. The proposed method was applicable to the determination of gold in platinum metal and its alloy as well as effluent without any interference by the matrices.