Schematic of the dry particle DESI setup. The electrospray emitter (a) was 4 mm away from the ion trap mass spectrometer (c). The angle between a and c was 60°. Nitrogen gas (N2) was used to assist the solvent (S) spray. Aerosol particles generated from a fluidized bed aerosol generator exited the tube (b). The angle between a and b was 90°.