Sequential determination of uranium and plutonium in soil and sediment samples by borate salts fusion

Abstract

This study describes a rapid method for sequential determination of uranium and plutonium isotopes in soil and sediment samples and its application to the study of Anthropocene sedimentary records. Different pretreatment methods have been tested (open-vessel digestion, borate salts fusion and NaOH salt fusion) achieving the complete dissolution of the sample in case of fusion methods. LiBO2 and Li2B4O7 (80/20) flux was finally selected because a higher amount of sample can be analyzed (up to 5 g). Moreover, separation steps with extraction chromatographic resin UTEVA were optimized. Average recoveries obtained for uranium and plutonium were acceptable, 59% and 72% respectively, and relative bias were below ± 15%. The time to complete the separation is approximately 11 h without ashing the samples and, consequently, it can be used in emergencies.