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

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.