Cloud point extraction for the preconcentration of palladium and lead in environmental samples and determination by flow injection flame atomic absorption spectrometry

An online cloud-point extraction (CPE) coupled with flow injection method is developed for the separation and preconcentration of palladium and lead from various matrices using flame atomic absorption spectrometry (FAAS). The method employs the formation of complexes of the metallic species with dimethylglyoxime, which are subsequently entrapped in the micelles of the surfactant Triton X-114, upon increase of the solution temperature to 60°C and loaded into the flow injection system at a flow rate of 4.6 mL min^sup -1^. The surfactant rich-phase was retained in a minicolumn packed with animal wool at pH 6 and eluted with 1.0 mol L^sup -1^ nitric acid in methanol at a flow rate of 1.1 mL min^sup -1^ directly into the nebulizer of the FAAS. The CPE variables and flow injection conditions affecting the analytical performance of the combined methodology was studied and optimized. Under the optimized conditions for 25 mL of preconcentrated solution, the enrichment factors were 51 and 44, and the limit of detections were 1.0 and 1.4 ng mL^sup -1^ for palladium and lead, respectively. Finally, the developed method was applied for the determination of palladium and lead in street dust, soil, radiology waste, catalytic converter, and urban aerosol samples. Cloud-point extraction coupled with flow injection-FAAS was proposed as an effective preconcentration and separation method for Pd and Pb determination in radiology waste, road dust, soil, and urban aerosol samples. The most favorable feature of this method is its much higher selectivity, sensitivity, rapidity, good extraction efficiency, and employs the green chemistry concept, as it does not require the addition of toxic chemicals. In addition, this proposed method gives very low detection limits and good relative standard.[PUBLICATION ABSTRACT]