Spray mechanism in paper spray ionization

Images and droplet size measurements show that paper spray operates in two distinct spray modes. Mode 1 occurs in solvent-rich systems in which multiple Taylor conejets are created producing droplets of a range of sizes. Mode 2 occurs at low solvent flow rates and the higher currents (similar to 1 uA) suggest a contribution from corona discharge. The latter experiment produces monodispersed droplet sizes. A distinguishing feature of paper spray in both modes is a fixed droplet velocity independent of droplet size. (C) 2012 Elsevier B.V. All rights reserved.