Monoaza 18-crown-6 ether (MACE) solvent extraction, preconcentration and determination with icp-oes of U(VI)

In the present study, extraction and preconcentration of U(VI) in matrix of 2-ethyl-N-benzyl-4,7,10,13,16-pentaoxa-1-azacyclooctadecane (MACE) and it was detected by Inductively Coupled Plasma Emission Spectroscopy (ICP-OES). In the experimental studies to determine optimum conditions, effect of several parameters such as extraction time, pH, volume of the sample solution, type and concentration of the eluent, and interfering ions were investigated and optimum conditions were determined. Jop's plot method was used to determine complex stoichiometry in MACE-U(VI) complex and L/M ratio was found. Furthermore, trace U(VI) in matrix was preconcentrated in the optimum conditions. In the experiments for determining optimum extraction time, 5-65 min was studied and it was found that all U(VI) passed to the organic phase in a 25 min of extraction. In the experiments to find how pH affects extraction yield of U(VI), a series of U(VI) solutions were prepared in the range of pH 2-10 and it was found that pH 7.0 was the best pH range, at which entire U(VI) passed into the organic phase. In the experiments to determine influence of the sample solution on extraction yield of U(VI), 5-100 mL solutions were prepared and it was found that the extraction yield reduced after 35 mL. For elution of U(VI), which forms a complex with MACE ligand in the organic phase, various concentrations (0.1-1.0 mol/L) of several acids, such as HNO3 and HCl were tested and 1.0 mol/L HNO3 was determined as the optimum eluent, by which U(VI) passed into the organic phase completely. Several ions such as K+, Na+, Zn2+, NH4+, Mg2+, Ca2+, Cd2+, Pb2+, Ni2+, Cu2+, Fe3+, Mn2+, - in high concentrations were added into the matrix solution in the optimum conditions found for effect of interfering ions on the extraction yield of U(VI), change in extraction yield was investigated and it was found that result in changes in extraction yield. Job's plot method was used to establish stoichiometry of MACE-U(VI) complex (L/M ratio), which formed in the organic phase under optimum conditions. Stoichiometry of the complex was found to be 1:1 and analysis in the organic phase was carried out at 279 nm by an UV-VIS Spectrophotometer. Finally, the developed method was applied to standard reference material (IAEA-Soil 7) sample in order to determine accuracy and precision of the method, and the results supported the developed method.