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

M Rezaee,F Khalilian

doi:10.4314/bcse.v29i3.4

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 C 18 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

Highlights

Uranium finds extensive application as nuclear fuel in power plants and their main sources are soil, rocks, plants, sand and water
In dispersive liquid-liquid microextraction (DLLME) the appropriate mixture of the extraction and disperser solvents is rapidly injected by a syringe into an aqueous solution containing ion complexes with chelating reagent
In order to examine the effect of the extraction solvent volume, 1.5 mL methanol containing different volumes of C6H5Cl (30.0, 40.0, 50.0, 60.0 and 70.0 μL) was subjected to the same Solid-phase extraction (SPE)-DLLME procedures

Summary

Introduction

Uranium finds extensive application as nuclear fuel in power plants and their main sources are soil, rocks, plants, sand and water. In DLLME the appropriate mixture of the extraction and disperser solvents is rapidly injected by a syringe into an aqueous solution containing ion complexes with chelating reagent. Solid-phase extraction (SPE) is a widely used sample preparation technique for the isolation of selected analytes.

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Conclusion