[S-GL17] 地球年代学・同位体地球科学

[SGL17-04] Advancements in precise ²³⁴U/²³⁸U measurements by multi-collector inductively coupled plasma mass spectrometry

★Invited Papers

Hsun-Ming Hu^1,2、*Chuan-Chou Shen^1,2、Chun-Yuan Huang^1,2、Pei-Yun Lu^1,2 (1.HISPEC, Department of Geosciences, National Taiwan University, Taipei, Taiwan, ROC、2.Research Center for Future Earth, National Taiwan University, Taipei, Taiwan, ROC)

キーワード：234U/238U measurement, MC-ICPMS techniques, two-sigma precision of one-epsilon

Uranium isotopes play a pivotal role across various disciplines in earth sciences. However, achieving accurate and precise measurements of the ²³⁴U/²³⁸U ratio has been challenging due to the four-order abundance difference between the two nuclides. In the past two decades, analytical techniques using multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) have been proposed, offering precision levels of 2-4 epsilons. In our study, we have developed MC-ICPMS techniques utilizing four different amplifiers (10^10, 10^11, 10^12, and 10^13 ohms), achieving a 2-sigma precision of 0.8-1.0 epsilon with 400-600 ng of uranium. Our protocol can also offer rapid precision attainment of 2-3 epsilon with only a 5-minute measurement time and consuming just 80-100 ng of uranium. This represents a significant advancement, reducing analysis time by threefold and requiring five times less sample size compared to current state-of-the-art techniques. Our isotopic analytical techniques hold promise for applications in geochronology, geochemistry, oceanography, and paleoclimatology.