A flow-modulated comprehensive gas chromatography–mass spectrometry method for the analysis of fatty acid profiles in marine and biological samples

The present investigation is focused on the development of a flow-modulator (FM) comprehensive 2D GC (GC × GC)-quadrupole mass spectrometry (qMS) approach, for the analysis of fatty acids. A recently developed flow modulator interfaced an apolar–polar column set, and was used for the first time with a mass spectrometer. Method development was achieved by using a standard mixture, containing fatty acid methyl esters (FAMEs). The total run time was approx. 40 min, thus relatively rapid. The optimized FM GC × GC–qMS method was applied to marine and biological FAMEs. Validation parameters such as intra-day and inter-day repeatability, limits of identification (mass spectral quality was evaluated at various FAME concentrations), and quantification were measured. Peak assignment was performed using pure standard compounds (when available), linear retention indices (LRIs), a dedicated FAME MS database, and specific bidimensional chromatogram positions. The MS database contained one-dimensional LRI information, exploited as a filter during the MS database search procedure. A good agreement was observed between database LRI values, and those calculated on the twin-column set. The FM GC × GC–qMS method can be considered as a valid counterpart, with respect to cryogenically modulated GC × GC, in the fatty acid field of research.