ON ICP-MS DETERMINATION OF URANIUM IN DRINKING, GROUND AND MINERAL WATERS

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 mu g L-1 for internal standard calibration. Analytical procedure developed is characterized by determination limit of 0.04 mu L-1 and relative standard deviation in the range 4-6% for the U concentration range from 0.04 to 50 mu L-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.