Electrospray Interface:

It also operates at atmospheric pressure and consists of a metal capillary tube through which column effluent is passed at a relatively low flow rate of 1-20 µL/min. An electric field is generated at the capillary exit by applying a 3-6 kV potential between the tube and a counter electrode placed at a distance away as shown in Figure (d). The field induces an accumulation of charge on the surface of the liquid emerging from the capillary resulting in the production of highly charged droplets. As the solvent evaporates, droplets shrink from their surface, which increases the charge density and leads to their explosive rupture and the creation of smaller charged droplets.

This process is repeated many times and finally multiply charged analyte species are formed. These are then passed through skimmers into the mass spectrometer where uncharged solvent molecules are pumped away. A variant, known as ion spray, involves pneumatic nebulization to increase the flow rate and an earthed screen to inhibit droplet condensation that would otherwise destabilize the spray.