236U/238U Analysis of Femtograms of236U by MC-ICPMS
Journal
Analytical Chemistry
Journal Volume
93
Journal Issue
24
Pages
8442-8449
Date Issued
2021
Author(s)
Abstract
A 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 Society
Subjects
Atoms
Electron multipliers
Inductively coupled plasma
Inductively coupled plasma mass spectrometry
Lead metallography
Sampling
Uranium
Accelerator mass spectrometry
Analytical method
Analytical precision
Inductively coupled plasma mass spectrometer
Polyatomic interferences
Reference material
Secondary electron multipliers
Triple quadrupole
Mass spectrometers
SDGs
Type
journal article