Precise determination of U isotopic compositions in low concentration carbonate samples by MC-ICP-MS

► A simple and fast method for precise U isotopic analysis was achieved by MC-ICP-MS. ► Only 12 ng U are needed for high precision isotopic determination. ► An effective UTEVA protocol for U separation was developed for various matrices. ► First high precision 238U/235U ratios in carbonate reference standards were measured.