POSSIBILITY OF THE SPECTROPHOTOMETRIC DETERMINATION OF EUROPIUM BY MEANS OF ARSENAZO III

Abstract

The concentration of Eu(III) cations in model aqueous solutions can be quantified by means of Arsenazo III reagent. Absorbance of the solution was measured at the wavelength λmax = 655 nm. Molar absorptivity reached the value ε655 = 5.5±0.2 · 10⁴ cm^-1 mol^-1 · dm³. Beer's law was obeyed in the range from 0 to 2 mg · dm^-3 Eu(III). The value of limit of detection was established by application of 3σ approach and reached the value of 20.9 μg · dm^-3. Repeatability of analysis expressed by relative standard deviation does not exceed the value of ± 8% and apparent recovery lay in acceptable range from 91 to 106 %. Stoichiometry between Eu(III) and Arsenazo III in media of relevant solution was 1:1. The absorbance of the solutions within the linear range of the proposed method maintained a constant value for 60 minutes. Described procedure can be utilized to determination of Eu(III) concentration in real samples, but it is necessary eliminate interfering ions. Cations like La(III), Sm(III), Th(IV), U(VI) and complexing agent EDTA cause significant error at the determination of Eu(III) in model solution. Presented spectrophotometric method could be applied for the determination of europium in the minerals and water samples, however after a suitable separation and preconcentration of target analyte.