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MS: Fachverband Massenspektrometrie

MS 2: Mass Spectrometry Methods

MS 2.5: Talk

Monday, March 14, 2022, 17:45–18:00, MS-H9

Investigation of mass-scale drift effects in the milli-mass range using MC-ICP-MS — •Axel Pramann, Janine Noordmann, and Olaf Rienitz — Physikalisch-Technische Bundesanstalt; Braunschweig, Germany

During the application of an MC-ICP magnetic sector field mass spectrometer, severe mass drift effects in the milli-mass range in the high resolution mode (M/ΔM = 8000) have been observed [1]. Their potential origins, experimental prevention, and the consequences are outlined. Additional simulations were performed using silicon enriched in 28Si as the main element in this investigation. One background is the fact that a drift of the mass scale influences the determination of isotope ratios strongly. For example, the signal-plateau width of 29Si+ in Si highly enriched in 28Si exhibits an extremely narrow mass plateau width of ΔM = 4 * 10-3 u, one of the smallest plateaus routinely investigated in isotope ratio measurements. A change of the magnetic field B, the acceleration voltage Uacc or the ESA voltage UESA by 0.01% induces respective changes of the mass scale of 6 * 10-3 u, 3 * 10-3 u, and 1 * 10-3 u, respectively. Electrical charging/discharging effects in the MS were observed and suggested to be affecting the mass scale stability. Therefore, the instrument was completely dismantled, grounded, and carefully reinstalled. Subsequent stability tests yielded a negligible mass drift of ΔM/Δt = 0.001 u/8 h, allowing for the measurement of isotope ratios with lowest uncertainty.

[1] A. Pramann, J. Noordmann, O. Rienitz, J. Mass Spectrom. 56:e4732 (2021)