Field-dependent [M – 2H]+. formation in the field desorption mass spectrometric analysis of hydrocarbon samples

✍ Scribed by Curt E. Heine; Marie M. Geddes

• Publisher: John Wiley and Sons
• Year: 1994
• Tongue: English
• Weight: 576 KB
• Volume: 29
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/oms.1210290603

✦ Synopsis

High

-boiling hydrocarbons often yield abundant IM -2H] + * ions under the conditions of field desorption mass spectrometry (FDMS). This work evaluated [ M -2HI + * formation from various saturated and aromatic compounds. The most intense [ M -2H1" signals observed resulted from the analysis of saturated compounds containing long and branched chains. The presence of an aromatic ring in a molecule, however, strongly diminished [ M -2H]+* formation during FDMS. Experiments involving manipulation of the applied potential between the F D anode and cathode reveal the strong field dependence of this phenomenon. At a potential difference of 10 kV, strong [ M -2Hj + * formation occurred for samples including squalane, hexatriacontane (C36 n-alkane) and a Polywax 655 mixture. Analyses of the same samples conducted at a potential difference of 4 kV produced only weak (if measurable) [ M -2H" signals. The magnitude of [ M -2H]+* formation also decreased as the sample quantity decreased.