Use of negative ion mass spectrometry for simultaneous determination of sulfur isotope ratios δ33S and δ34S

We describe a newly constructed dual inlet system and triple collector for precision study of sulfur isotope anomalies, Δ33S, using negative ion mass spectrometry. SO2 gas is admitted to the ion source where it is ionized ether to SO- or S- by low energy electrons (resonant ionization) and the ion beam is analyzed by a single focusing magnetic analyzer. Another gas which can be used for  δ33S and δ34S analysis by negative ion mass spectrometry  is SF6 on mass spectrum of SF5- ions.