Precise Measurement of Tellurium Isotope Ratios in Terrestrial Standards Using a Multiple Collector Inductively Coupled Plasma Mass Spectrometry

Abstract

Precise tellurium (Te) isotope ratio measurement using mass spectrometry is a challenging task for many decades. In this paper, Te isotope ratio measurements using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) in terrestrial Te standards have been reported. Newly developed Faraday cup with 10¹² Ω resistor is used to measure low abundance ¹²⁰Te, whereas the 10¹¹ Ω resistor is used to measure other Te isotopes. The relative standard deviation obtained for Te isotope ratio measurement by Faraday cups of ¹²⁰Te/¹²⁸Te [0.002907(05)], ¹²²Te/¹²⁸Te [0.079646(10)], ¹²³Te/¹²⁸Te [0.027850(07)], ¹²⁵Te/¹²⁸Te [0.221988(09)], ¹²⁶Te/¹²⁸Te [0.592202(20)], and ¹³⁰Te/¹²⁸Te [1.076277(30)] were 0.140%, 0.014%, 0.026%, 0.005%, 0.004%, and 0.004%, respectively. The measured isotope ratio results are compared with previous results obtained by thermal ionization mass spectrometry (TIMS), negative thermal ionization mass spectrometry (N-TIMS), and MC-ICP-MS, showing an improvement in the precision about one order of magnitude for ¹²⁰Te/¹²⁸Te ratio. The present study shows better precision for Te isotope ratios compared to earlier studies.

Keywords: MC–ICP–MS; tellurium isotope ratios; terrestrial standards.