Charge-exchange reactions with water in the detection of perfluorocarbons by thermospray liquid chromatography/mass spectrometry

✍ Scribed by S. K. Huang; D. H. Klein; M. McLoughlin

• Publisher: John Wiley and Sons
• Year: 1989
• Tongue: English
• Weight: 370 KB
• Volume: 18
• Category: Article
• ISSN: 1076-5174
• DOI: 10.1002/bms.1200180204

✦ Synopsis

Peduorocarbons (PFCs) can be detected by thermospray liquid chromatography/mass spectrometry (LC/MS) only when the system is operated in the negative ion mode with filament on and some water entering the thermospray source. A new mechanism for PFC ionization is proposed, based on studies of LC/MS detection of the perfluorinated forms of cyclohexane, methyl and dimethyl cyclohexane, decalin, 1-methyl decalin and toluene. The ion evaporation mechanism of Dodd, involving pre-ionization of PFCs in the presence of aqueous NH,OAc, is not operative, nor is chemical ionization of PFCs by the reagent ions as in true thermospray LC/MS. Instead, PFC ionization is attributable to the negative ions formed from the water in the source; these ions undergo prompt charge-exchange reactions with the more electronegative PFCs to form structure-retaining PFC ions.