Isotope ratio analysis of actinides, fission products, and geolocators by high-efficiency multi-collector thermal ionization mass spectrometry

A ThermoFisher Triton multi-col lector thermal ionization mass spectrometer (MC-TIMS) was evaluated for trace and ultra-trace level isotope ratio analysis of actinides (uranium, plutonium, and americium), fission products and geolocators (strontium, cesium, and neodymium). Total efficiencies (atoms loaded to ions detected) of up to 0.5-2% for U, Pu, and Am, and 1-30% for Sr, Cs, and Nd can be reported employing resin bead load techniques onto flat ribbon Re filaments or resin beads loaded into a millimeter-sized cavity drilled into a Re rod. This results in detection limits of < 0.1 fg (10(4) atoms to 10(5) atoms) for Pu239-242+244, U233+236, Am241-243, Sr-89,Sr-90, and Cs-134,Cs-135,Cs-137, and <= 1 pg for natural Nd isotopes (limited by the chemical processing blank) using a secondary electron multiplier (SEMI) or multiple-ion counters (MICs). Relative standard deviations (RSD) as small as 0.1% and abundance sensitivities of 1 x 10(6) or better using a SEMI are reported here. Precisions of RSD approximate to 0.01-0.001% using a multi-collector Faraday cup array can be achieved at sub-nanogram concentrations for strontium and neodymium and are suitable to gain crucial geolocation information. The analytical protocols reported herein are of particular value for nuclear forensic and nuclear safeguard applications. (C) 2009 Elsevier B.V. All rights reserved.