Eliminating Mo isobaric interference using O 2 as reaction gas for Tc measurement by triple quadrupole ICP-MS

• Published in: Journal of analytical atomic spectrometry Vol. 37; no. 6; pp. 1174 - 1178
• Main Authors: Bu, Wenting, Yang, Liang, Tang, Lei, Xiong, Ke, Ni, Youyi, Yang, Chuting, Hu, Sheng
• Format: Journal Article
• Language: English
• Published: 08.06.2022
• ISSN: 0267-9477; 1364-5544
• DOI: 10.1039/D2JA00104G

Monitoring of ultra-trace level 99 Tc in environmental samples is important for radioactivity assessment and tracing oceanographic processes. 97 Tc is an ideal yield tracer for the analysis of 99 Tc. However, when using 97 Tc as the tracer for 99 Tc measurement in environmental samples, complex and tedious chemical separation procedures were needed for the separation of isobaric interference of 97 Mo. In this work, for the first time, we reported a method for the measurement of Tc isotopes by triple quadrupole ICP-MS (ICP-MS/MS). An APEX-Ω high efficiency sample introduction system was used for the improvement of the instrument sensitivity. The absolute detection limit for 99 Tc was estimated to be 0.9 fg (0.6 mBq). We introduced O 2 gas into the reaction cell of ICP-MS/MS. The majority of Mo + reacted with O 2 to form MoO + and MoO 2 + ions, which were eliminated by the second mass filter behind the reaction cell. A high separation factor (>1000) of Mo and Tc was found at an O 2 flow rate of 70%. By using this method, the effect of trace amounts of Mo in the sample solution on the measurement of Tc could be negligible.