Lin H.-TChiang H.-WYu T.-LChristl MLiu JDeLong KCHUAN-CHOU SHENHUEI-TING LIN2022-04-252022-04-25202100032700https://www.scopus.com/inward/record.uri?eid=2-s2.0-85108702859&doi=10.1021%2facs.analchem.1c00409&partnerID=40&md5=5f36f04305d0674f1154bb93227ee1e7https://scholars.lib.ntu.edu.tw/handle/123456789/606212A new analytical method has been developed to determine atomic236U/238U ratios in samples with only femtograms of236U using a secondary electron multiplier (SEM) on a multicollector high-resolution inductively coupled plasma mass spectrometer (MC-ICPMS). The abundance sensitivity of the238U tail at 236 atomic mass unit is reduced from 10-6to 10-10with the deployment of a retarding potential quadrupole lens. This method features the reduction of polyatomic interferences from hydride, nitride, lead, and plutonium and the evaluation of nonlinear SEM behavior. The instrument sensitivity is 1-2%, and the estimated methodological detection limit of the236U/238U atomic ratio is as low as 2 × 10-10. Measurements on reference materials with236U/238U ratios of 10-7-10-9, including the IRMM-075 series and the ETH Zurich in-house standard ZUTRI, demonstrate the accuracy of our MC-ICPMS technique. The analytical precisions (2σ) are ±4% for 5 fg of236U at a236U/238U of 1 × 10-8and ±8% for 2 fg of236U at a236U/238U of 4 × 10-9level. Compared to state-of-the-art accelerator mass spectrometry techniques and triple quadrupole-based ICPMS, our detection limit is not as low, but the required sample size is 3-40 times lower, and the throughput is as high as 3-4 samples per hour. The new MC-ICPMS-SEM technique is sensitive enough for determining236U/238U in various small natural samples, such as marine carbonates and seawater. ? 2021 American Chemical SocietyAtomsElectron multipliersInductively coupled plasmaInductively coupled plasma mass spectrometryLead metallographySamplingUraniumAccelerator mass spectrometryAnalytical methodAnalytical precisionInductively coupled plasma mass spectrometerPolyatomic interferencesReference materialSecondary electron multipliersTriple quadrupoleMass spectrometers[SDGs]SDG14journal article10.1021/acs.analchem.1c004092-s2.0-85108702859