Chemical ionization mass spectrometry as a tool for the elimination of surface related phenomena in the spectra of unstable compounds

Journal Article · Tue Jan 31 23:00:00 EST 1978 · Anal. Chem.; (United States)

DOI:https://doi.org/10.1021/ac50024a049· OSTI ID:5121053

Smith, R D; Ryan, P W

The occurrence of surface related reactions in mass spectrometer ion sources has long been recognized. The products of gas--surface reactions, involving surface ionization on the filament and pyrolysis on hot surfaces, often contribute minor peaks to electron impact (EI) mass spectra, and complications can be severe in the analysis of reactive or thermally unstable compounds. The resulting mass spectra may lead to an assumption of the presence of impurities not actually in the sample, or even cause errors in the identification of unknown compounds and mixtures. The purpose of this correspondence is to present an example of such surface related phenomena and to point out how these problems may be avoided utilizing chemical ionization (CI) mass spectrometry. The compound used to illustrate this problem is the brominated derivative of polymeric, sulfur nitride, (SN)/sub x/. (SN)/sub x/ has been previously found to produce a noncyclic (SN)/sub 4/ species upon sublimation. The brominated derivative, of empirical formula SNBr/sub 0/./sub 4/, was expected to yield (SN)/sub 4/ plus an unknown brominated species upon sublimation; hence, identification of the bromine containing species was of particular interest. Results show that argon (in the absence of a large water impurity) offers a distinct advantage for the analysis of mixtures over more commonly used methane, isobutane, and ammonia as a CI reagent. The latter involve relatively low energy proton transfer processes; hence, molecular species such as Br/sub 2/ and S/sub 8/ are not ionized by isobutane and NH/sub 3/ CI. Charge transfer from argon ions (Ar/sup +/ and Ar/sub 2//sup +/ are the major reagent ions in this work) is a much higher energy process and is capable of ionizing most molecules. (JRD)

• Research Organization: Battelle Pacific Northwest Labs., Richland, WA
• OSTI ID: 5121053
• Journal Information: Anal. Chem.; (United States), Journal Name: Anal. Chem.; (United States) Vol. 50:2; ISSN ANCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400104* -- Spectral Procedures-- (-1987)
ALKANES
AMMONIA
ARGON IONS
BROMIDES
BROMINE COMPOUNDS
CHARGED PARTICLES
CRYOGENIC FLUIDS
FLUIDS
HALIDES
HALOGEN COMPOUNDS
HYDRIDES
HYDROCARBONS
HYDROGEN COMPOUNDS
IONIZATION
IONS
MASS SPECTROSCOPY
METHANE
MOLECULAR IONS
NITRIDES
NITROGEN COMPOUNDS
NITROGEN HYDRIDES
ORGANIC COMPOUNDS
PNICTIDES
SPECTROSCOPY
SULFUR COMPOUNDS
SULFUR NITRIDES
SURFACE PROPERTIES