Extracting inert gases from water samples for analysis on a magnetic resonance mass spectrometer

Abstract

A system for extracting and purifying inert gases from water samples has been developed that ensures the isolation of more than 90% of He and Ne dissolved in water. The system is linked to a magnetic resonance mass spectrometer (MRMS) that is used for determining the peaks of helium and neon isotopes and performing calibration measurements of reference gas mixtures. On this basis, the absolute amounts of ³He, ⁴He, and ²⁰Ne as well as the isotope ratios of ³He/⁴He and ⁴He/²⁰Ne in the sample are calculated with a good precision. The errors of determination depends on the amounts of isolated gases and the uncertainty of electrode potential adjustment in the ion source (for the MRMS operating in a double-beam mode); in the case of measurements on the static stage (for neon ions), an additional error component is related to the jumplike switching of the accelerating voltage.