Comprehensive Dipeptide Analysis by Pre-column Derivatization LC/MS/MS

Dipeptides are expected to improve the physical properties of amino acid, to have a new physical description and a physiological function. However, there was almost no practical method for a comprehensive analysis of dipeptides, and there were only few reports that examined those existences, behavior or functions. In the present study, we developed a comprehensive analytical method for dipeptides, using pre-column derivatization coupled to reversed-phase high-performance liquid chromatography/electrospray ionization tandem mass spectrometry (LC/MS/MS). Dipeptides samples were derivatized with phenyl isocyanate (PIC), which is able to react under the mild condition to the free amino group. The resulting typical derivatives were analyzed by tandem mass spectrometry and specific cleavages in the collision induced dissociation (CID) were observed. These fragmentation patterns have been enabled for practical analysis combined with the predicted selected reaction monitoring (pSRM), precursor ion scan or constant neutral loss scan. With these developed methods, we demonstrated to be able to show dipeptide profiles of food samples, such as cheese and wine.