Ultrasound-assisted emulsification--solidified floating organic drop microextraction combined with flow injection--flame atomic absorption spectrometry for the determination of palladium in water samples

The ultrasound-assisted emulsification--solidified floating organic drop microextraction (USAE--SFODME) methodology was combined with flow injection--lame atomic absorption spectrometry (FI--FAAS) for the separation/pre-concentration and determination of palladium at ultratrace level. In this method, the palladium ion in the aqueous solution was complexed with acetylacetone (6 times 10^{-3} mol L^{-1}) in the pH range of 1--7 and was extracted into 40 mu L of 1-undecanol, which was sonically dispersed in the aqueous phase. The vial was then centrifuged and cooled in an ice bath for 5 min. The solidified extract was melted and diluted to 100 mu L with a solution of hydrochloric (1 mol L^{-1}) acid in ethanol, and the concentration of palladium was determined by FI--FAAS. Under the optimum conditions, an enhancement factor of 55 and a good relative standard deviation of pm 2.1% at 40 mu g L^{-1} were obtained (n = 7). The proposed method was successfully applied to the determination of palladium in different types of water samples. Accuracy was assessed through recovery experiments, independent analysis by furnace atomic absorption spectrometry, and analysis of a certified reference ore by the proposed method.