Portal de Periódicos da CAPES

Negative‐ion mass spectrometry in a commercial gas chromatography/ion‐trap mass spectrometer system

1995; Wiley; Volume: 9; Issue: 13 Linguagem: Inglês

10.1002/rcm.1290091316

1097-0231

Silvia Catinella, Pietro Traldi, Xuewu Jiang, Frank A. Londry, Richard J. S. Morrison, Raymond E. March, Sébastien Grégoire, Jean‐Charles Mathurin, Jean‐Claude Tabet,

Analytical Chemistry and Chromatography

Abstract Commercial gas chromatography quadrupole ion‐trap mass spectrometer (GC/ITMS) instruments have been used in a novel way for the study of negative ions formed from perfluorotributyl‐amine and polychlorinated biphenyl compounds. Negative ions, formed during a normal electron impact ionization period in which 70 eV electrons were used, were isolated in an ion trap by the application of a negative DC voltage to the ring electrode that caused all positive ions to be ejected from the ion trap; in the subsequent analytical scan, negatives ions were detected with an electron multiplier biased normally so as to detect positive ions. The major negative‐ion species detected from FC‐43 were m/z 252 to m/z 633; 34 other negative‐ion species were detected also, though in low abundance. The observed negative‐ion mass range extended from m/z 252 to m/z 633. The signal‐to‐noise ratio of negative‐ion mass spectra was enhanced by operation of the GC/MS instrument in GC mode and averaging the mass spectra acquired. In an examination of 3 hexachlorobiphenyl compounds, the molecular anion cluster around m/z 360 for the non‐ ortho ‐substituted congener 169 was observed with a signal‐to‐noise ratio of ca. 20 for 90 pg injected on column: the response for congener 169 was greater than that for congener 156 (mono‐ ortho ‐substituted) which, in turn, was greater than that for congener 153 (di‐ ortho ‐substituted).