The sensitivity of volumetric flow rate to applied voltage in cone-jet mode electrospray and the influence of solution properties and emitter geometry

A high accuracy online flow rate measurement system has been used to demonstrate the effect of applied voltage, Vapp, on the volumetric flow rate, Q, through an electrospray system. Several solutions of the organic solvents ethylene and triethylene glycols doped with sodium iodide to give varying conductivities in the range of 0.0025-0.23 S/m have been sprayed. It was established for the first time that solution conductivity has no appreciable effect on the sensitivity of flow rate to applied voltage in the cone-jet mode of electrospray. However, it appears that even when the hydraulic resistance is taken into account, the sensitivity of flow rate as controlled by the applied voltage is additionally related to the emitter exit geometry. These findings are of particular importance to both spacecraft propulsion and electrospray mass spectrometry technologies and suggest careful emitter geometry design considerations will lead to greater control over electrospray properties. © 2006 American Institute of Physics.