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Rapid Commun Mass Spectrom

Title:		A new negative and positive gas ion source for isotope ratio mass spectrometry
Author(s):		Pienkos T; Halas S;
Address:		"Mass Spectrometry Laboratory, UMCS Lublin, Pl. M. Curie-Sklodowskiej 1, 20-031, Lublin, Poland"
Journal Title:		Rapid Commun Mass Spectrom
Year:		2017
Volume:		31
Issue:		11
Page Number:		964 - 968
DOI:		10.1002/rcm.7879
ISSN/ISBN:		1097-0231 (Electronic) 0951-4198 (Linking)
Abstract:		"RATIONALE: The goal of this research was to construct an effective gas ion source for isotope ratio mass spectrometry, which generates sufficiently strong and stable ion beams for multiple isotope ratio analysis of sulfur and oxygen from readily available gases such as SO(2) , CO(2) , CO, O(2) and chlorine from CH(3) Cl gas. METHODS: By means of a 60 degrees sector mass spectrometer equipped with a new type of sensitive ion source and with a dual-inlet system and triple collector assembly, we have measured (34) S/(32) S and challenging (36) S/(32) S isotope ratios using positive sulfur ions generated from SO(2) gas. The new ion source differs from the Nier-type ones by the electron beam being replaced with a tungsten filament. The obtained isotope signals of (32) S(+) , (34) S(+) and (36) S(+) were from 1 to 5 V (depending on the pressure of admitted gas) on high-ohm resistors of 200 MOmega, 5 GOmega and 500 GOmega, respectively. The variable (33) S peak was not recorded as useful due to interference from H(32) S(+) ions. RESULTS: Although the ionizing electrons in the new ion source have significant energy dispersion the obtained peak profiles are flat-topped and they lead to good resolving power for the mass spectrometer (M/?OsM approximately 100). The achieved precision of delta(34) S and delta(36) S determination was better than +/-0.01 and +/-0.1 per thousand, respectively. The determination of (37) Cl/(35) Cl in a volatile organic compound CH(2) Cl(2) was easily achieved on Cl(-) negative ions with a precision of +/-0.005 per thousand. CONCLUSIONS: The new ion source has great potential in the quantitative analysis of gases on positive ion mass spectra as well as, in the case of gases with high electron affinity such as CH(3) Cl, CH(3) Br, SF(6) , SiF(4) , on negative ones. It usefulness was demonstrated on an example of multiple sulfur isotope analysis and (37) Cl/(35) Cl ratio determination with great precision. A negative ion source of this type will probably be useful in a more complicated instruments used in SIMS or AMS. Copyright (c) 2017 John Wiley & Sons, Ltd"
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Notes:		"PubMed-not-MEDLINEPienkos, Tomasz Halas, Stanislaw eng England 2017/04/14 Rapid Commun Mass Spectrom. 2017 Jun 15; 31(11):964-968. doi: 10.1002/rcm.7879"