Uranium determination in process chemicals: on the way to sub-pg/g concentrations

The detection limit of ICP-MS is affected by the sensitivity, the height of the blank and its relative stability i.e. precision, the accuracy and additionally by a bias or systematical error. The improvement of a single factor will improve the efficiency of the whole analytical system. For the example of uranium determination in process chemicals such as concentrated HF and HNO₃ the improvement or deterioration of the factors given above is demonstrated. The applied methods are matrix removal by evaporation, highly efficient nebulization with a USN, isotope dilution and use of a double-focusing instrument (ICP-SFMS_LR). The increase or decrease of each factor is compared to conventional nebulization ICP-QMS. To take full advantage of each single method, they can be combined with each other. Possible drawbacks of a single method are compensated by another method. Detection limits for uranium in concentrated process chemicals in the sub-pg/g range can be achieved.