Electrospray Ionization and Collision Induced Dissociation Mass Spectrometry of Primary Fatty Acid Amides

Primary fatty acid amides are a group of bioactive lipids that have been linked with a variety of biological processes such as sleep regulation and modulation of monoaminergic systems. As novel forms of these molecules continue to be discovered, more emphasis will be placed on selective, trace detection. Currently, there is no published experimental determination of collision induced dissociation of PFAMs. A select group of PFAM standards, 12 to 22 length carbon chains, were directly infused into an electrospray ionization source Quadrupole Time of Flight Mass Spectrometer. All standards were monitored in positive mode using the [M + H](+) peak. Mass Hunter Qualitative Analysis software was used to calculate empirical formulas of the product ions. All PFAMs showed losses of 14 m/z indicative of an acyl chain, while the monounsaturated group displayed neutral losses corresponding to H2O and NH3. The resulting spectra were used to propose fragmentation mechanisms. Isotopically labeled PFAMs were used to validate the proposed mechanisms. Patterns of saturated versus unsaturated standards were distinctive, allowing for simple differentiation. This determination will allow for fast, qualitative identification of PFAMs. Additionally, it will provide a method development tool for selection of unique product ions when analyzed in multiple reaction monitoring mode.