Rapid determination of ultra-trace plutonium in large volume of urine samples by tandem quadrupole inductively coupled plasma-mass spectrometry

Highlights: • Tandem quadrupole ICP-MS was utilized to measure Pu isotopes in large volume of urine samples. • The interference of ²³⁸U (0.23 cps) would be much less a concern at 4.0 mL min⁻¹ NH₃ and 3.0 mL min⁻¹ He. • The detection limits of ²³⁹Pu (0.83 fg/L) and ²⁴⁰Pu (0.14 fg/L) are suitable for Pu routine analysis of urine. Rapid bioassay method for plutonium in urine samples are employed to assess the possible internal dose resulting from exposure to plutonium in the event of a radiological and nuclear emergency. In this work, a rapid method for the determination of plutonium isotopes (²³⁹Pu and ²⁴⁰Pu) in large volume of urine samples was developed using tandem quadrupole ICP-MS combined with a high-efficiency sample introduction system (APEX-Ω). The mixture gases of NH₃ and He was employed to effectively eliminate the tailing of ²³⁸U and the uranium hydride ions (²³⁸U¹H⁺and ²³⁸U¹H₂⁺) and significantly improve the measurement sensitivity of plutonium. The method was validated by analyzing urine samples spiked with known amounts of ²³⁹Pu and ²⁴⁰Pu ranging from 1 to 60 fg. The detection limits for the method were estimated to be 0.83 fg for ²³⁹Pu, 0.14 fg for ²⁴⁰Pu in 1 L of urine.