A Stable Dicationic Salt in Reactive DESI-MS Imaging in Positive Ion Mode to Analyze Biological Samples

A dicationic salt was applied for imaging in reactive desorption electrospray ionization mass spectrometry (DESI-MS) on biological samples. The samples interrogated in this experiment were whole body zebrafish tissues and rat brain tissue. The stable dictation salt forms a stable bond with biological tissue fatty acids and lipids and allows detection in positive ion mode. Reactive DESI-MS imaging in positive ion mode of rat brain and zebrafish tissues allowed enhanced detection of certain compounds commonly observed in negative ion mode. Variance in intensity between negative and positive mode indicate that the ionization process could be affected by matrix effects of various tissues, leading to different overall intensity which could provide new information on the same compounds when compared between negative ion mode images and reactive DESI positive ion mode images.