An emergency radiobioassay method for Pu, Am and Cm isotopes in urine samples using tandem quadrupole ICP-MS†

Abstract

The rapid bioassay method for measuring actinides in human urine samples is the most appropriate way for the assessment of internal exposure doses during radiological and nuclear emergencies. A rapid simultaneous analysis method for ²³⁹Pu, ²⁴⁰Pu, ²⁴¹Am and ²⁴⁴Cm in 100 mL urine samples was established by using tandem quadrupole ICP-MS (ICP-MS/MS), combined with a hydrous titanium oxide (HTiO) co-precipitation step and a tandem small size resin column (TEVA + DGA) purification step for shortening the sample processing time. The ICP-MS/MS measurements of Pu isotopes, ²⁴¹Am and ²⁴⁴Cm were optimized in Q3 only mode and MS/MS mode, respectively, and the interferents from the urine matrix were appropriately suppressed by applying Axial Field Voltage (AFT). The measurement sensitivities of Pu and Am isotopes were improved by employing NH₃ or He as collision/reaction cell gases, and an interesting finding is that pure NH₃ significantly improved the Pu measurement sensitivity. The detection limits for the method were estimated to be 1.12 fg (2.57 × 10⁻³ mBq) for ²³⁹Pu, 0.97 fg (8.14 × 10⁻³ mBq) for ²⁴⁰Pu, 1.46 fg (0.19 mBq) for ²⁴¹Am and 0.74 fg (2.16 mBq) for ²⁴⁴Cm in 100 mL urine, meeting the sensitivity requirements for emergency urine bioassay methods.