A Facile Vortex-Assisted Dispersive Liquid-Liquid Microextraction Method for the Determination of Uranyl Ion at Low Levels by Spectrophotometry

A facile and reliable UV-Vis spectrophotometric method associated with vortex-assisted dispersive liquid-liquid microextraction has been developed and applied to the determination of U(VI) at low levels in water samples. It was based on preconcentration of 24.0 mL sample at pH 8.0 in the presence of 7.4 A mu mol L-1 1-(2-pyridylazo)-2-naphthol, 1.0 mL of methanol as disperser solvent and 1.0 mL of chloroform as extraction solvent. A high preconcentration factor was achieved (396 times), thus providing a wide analytical curve from 6.9 up to 75.9 A mu g L-1 (r = 0.9982) and limits of detection and quantification of 0.40 and 1.30 A mu g L-1, respectively. When necessary, EDTA or KCN can be used to remove interferences of foreign ions. The method was applied to the analysis of real water samples, such as tap, mineral and lake waters with good recovery values.