Preconcentration of uranium in water samples using dispersive liquid-liquid micro- extraction coupled with solid-phase extraction and determination with inductively coupled plasma-optical emission spectrometry

Abstract

A new liquid phase microextraction method based on the dispersion of an extraction solvent into aqueous phase coupled with solid-phase extraction was investigated for the extraction, preconcentration and determination of uranium in water samples. 1-(2-Pyridylazo)-2-naphthol reagent (PAN) at pH 6.0 was used as a chelating agent prior to extraction. After concentration and purification of the samples in SPE C₁₈ sorbent, 1.5 mL elution sample containing 40.0 µL chlorobenzene was injected into the 5.0 mL pure water. After extraction and centrifuging, the sedimented phase was evaporated and the residue was dissolved in nitric acid (0.5 M) and was injected by injection valve into the ICP-OES. Some important extraction parameters, such as sample solution flow rate, sample pH, type and volume of extraction and disperser solvents as well as the salt addition were studied and optimized. Under the optimum conditions, the calibration graph was linear in the range of 0.5-500 µg L^-1. The detection limit was 0.1 µg L^-1. The relative standard deviation (RSD) at 5.0 µg L^-1 concentration level was 6.6%. Finally, the developed method was successfully applied to the extraction and determination of uranium in the well, river, mineral, waste and tap water samples and satisfactory results were obtained.

KEY WORDS: Dispersive liquid-liquid microextraction, Solid-phase extraction, Inductively coupled plasma-optical emission spectrometry, Uranium, Water samples

Bull. Chem. Soc. Ethiop. 2015, 29(3), 367-376. 

DOI: http://dx.doi.org/10.4314/bcse.v29i3.4