No abstract

A method for the determination of uranium in surface and ground water samples is developed and validated. The method is based on ICP-MS measurement under optimized instrumental parameters using Re as an internal standard. Model solutions containing major cations in natural waters such as Na, K, Ca, Mg are prepared and used to study the observed matrix interferences on U signal in ICP-MS measurements. Routinely used internal standards La, Tl for U ICP-MS measurement in natural waters are compared to newly proposed internal standard Re. Results obtained showed more efficient interference correction and better reproducibility in the presence of Re applied at concentration level of 10 μg L−1 for internal standard calibration. Analytical procedure developed is characterized by determination limit of 0.04 μL−1 and relative standard deviation in the range 4–6% for the U concentration range from 0.04 to 50 μL−1. The method is validated through the analysis of parallel water samples by using proposed method, by using standard UV-VIS method (arsenazo III), and by analyzing a certified reference material.

An analytical method for uranium determination in waters, wine and honey was developed based on solid phase extraction (SPE) with new ion imprinted polymer. The sorbent was synthesized using 4-(2-Pyridylazo)resorcinol (PAR) as a ligand via dispersion polymerization and characterized by SEM for morphology and shape of polymer particles and nitrogen adsorption–desorption studies for their surface area and total pore volume. The kinetic experiments performed showed that the rate limiting step is the complexation between U(VI) ions and chelating ligand PAR incorporated in the polymer matrix. Investigations by Freundlich and Langmuir adsorption isotherm models showed that sorption process occurs as a surface monolayer on homogeneous sites. The high extraction efficiency of synthesized sorbent toward U(VI) allows its application for SPE determination of U(VI) in wine and honey without preliminary sample digestion using ICP-OES as measurement method. The recoveries achieved varied: (i) between 88 to 95% for surface and ground waters, (ii) between 90–96% for 5% aqueous solution of honey, (iii) between 86–93% for different types of wine. The validity and versatility of proposed analytical methods were confirmed by parallel measurement of U in water samples using Alpha spectrometry and U analysis in wine and honey after sample digestion and ICP-MS measurement. The analytical procedure proposed for U determination in surface waters is characterized with low limits of detection/quantification and good reproducibility ensuring its application for routine control in national monitoring of surface waters. The application of proposed method for honey and wine samples analysis provides data for U content in traditional Bulgarian products.