TY - JOUR
T1 - Determination of Picogram-per-Gram Concentrations of 231Pa and 230Th in Sediments by Melt Quenching and Laser Ablation Mass Spectrometry
AU - Zheng, Jianfan
AU - Chen, Tianyu
AU - Ng, Hong Chin
AU - Robinson, Laura F.
AU - Zheng, Xin Yuan
AU - Shi, Xuefa
AU - Huang, Mu
N1 - Publisher Copyright:
© 2022 American Chemical Society.
PY - 2022/5/31
Y1 - 2022/5/31
N2 - Uranium, thorium, and protactinium radionuclides in marine sediments are important proxies for understanding the earth's environmental evolution. Conventional solution-based methods, which typically involve isotope spike preparation, concentrated acid sample digestion, column chemistry, and mass spectrometry, allow precise but time-consuming and costly measurements of these nuclide concentrations (i.e., 230Th and 231Pa). In this work, we have established an efficient method for 230Th and 231Pa measurement of marine sediments down to the picogram-per-gram level without purification and enrichment. Our method first transforms a small amount of thermally decomposed sediments (∼0.1-0.2 g) to homogeneous silicate glass using a melt quenching technique and then analyzes the glass with laser ablation multicollector inductively coupled plasma-mass spectrometry. Standard sample bracketing with isotope-spike-calibrated glass standards prepared in this study was used to correct for instrumental fractionation during measurement. It is demonstrated that our method can accurately determine the U-Th-Pa concentrations of typical marine sediments in the late Pleistocene with precision of a few percent. Compared with the conventional solution-based methods, the turnover time of sample preparation and measurement with our established protocol is greatly reduced, facilitating future application of U-series radionuclides in reconstructing oceanic processes at high temporal and spatial resolution.
AB - Uranium, thorium, and protactinium radionuclides in marine sediments are important proxies for understanding the earth's environmental evolution. Conventional solution-based methods, which typically involve isotope spike preparation, concentrated acid sample digestion, column chemistry, and mass spectrometry, allow precise but time-consuming and costly measurements of these nuclide concentrations (i.e., 230Th and 231Pa). In this work, we have established an efficient method for 230Th and 231Pa measurement of marine sediments down to the picogram-per-gram level without purification and enrichment. Our method first transforms a small amount of thermally decomposed sediments (∼0.1-0.2 g) to homogeneous silicate glass using a melt quenching technique and then analyzes the glass with laser ablation multicollector inductively coupled plasma-mass spectrometry. Standard sample bracketing with isotope-spike-calibrated glass standards prepared in this study was used to correct for instrumental fractionation during measurement. It is demonstrated that our method can accurately determine the U-Th-Pa concentrations of typical marine sediments in the late Pleistocene with precision of a few percent. Compared with the conventional solution-based methods, the turnover time of sample preparation and measurement with our established protocol is greatly reduced, facilitating future application of U-series radionuclides in reconstructing oceanic processes at high temporal and spatial resolution.
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U2 - 10.1021/acs.analchem.2c00438
DO - 10.1021/acs.analchem.2c00438
M3 - Article
C2 - 35576450
AN - SCOPUS:85131349630
SN - 0003-2700
VL - 94
SP - 7576
EP - 7583
JO - Analytical Chemistry
JF - Analytical Chemistry
IS - 21
ER -