A microextraction method for spectrophotometric determination of gold using benzalkonium chloride

A simple microextraction method has been developed for the preconcentration of Au(III) and its measurement by an ultraviolet–visible spectrophotometer. Benzalkonium chloride, a cationic surfactant, was used as a complexing agent for the preconcentration of Au(III) in the form of AuCl₄⁻. An ion pair between AuCl₄⁻ and benzalkonium chloride was finely extracted into the 1,2-dichloroethane phase through a simple emulsification process. Parameters affecting the preconcentration of Au(III) were evaluated, including the acidity of the solution, the amount of the cationic reagent, and the effect of interferences. The calibration curve of the method for Au(III) was linear in the range of 0.05–0.80 mg L⁻¹. The detection limit, enrichment factor, and relative standard deviation were 0.01 mg L⁻¹, 40, and 1.9%, respectively. The accuracy of the method was evaluated through addition-recovery tests on real water samples. The results demonstrate that this microextraction method was successfully applied to stream water samples for the preconcentration of Au(III).