Collision-induced dissociation mass spectrometry of nonionic surfactants following direct supercritical fluid injection.

Direct injection from a capillary supercritical fluid chromatography system was used as an inlet technique for chemical ionization (CI) and low energy collision-induced dissociation (CID) mass spectrometry of a series of low volatility nonionic surfactant mixtures. Characteristic fragment ions produced by CID for various classes of nonionic surfactant molecules were found to depend greatly on the structure of the surfactant hydrophobe. This was the case even when the charge on the molecule appeared localized away from the hydrophobe. Numerous decomposition pathways are suggested by the fragment ions produced. The use of direct supercritical fluid injection as an inlet technique does not appear to influence adversely the ability to produce cm mass spectra. Direct supercritical fluid introduction allows CI to be compared with other ionization mechanisms more commonly used for multifunctional, low volatility samples.