Generating Electrospray from Microchip Devices Using Electroosmotic Pumping

TLDR

The paper presents a method for generating electrospray from solutions exiting microchip channels, describing and demonstrating the principles governing fluid delivery. Electroosmotic pressures drive fluids through etched microchip channels, and a sufficient electrical potential applied at the channel terminus generates electrospray between the chip and a nearby conductor, requiring only channel opening exposure. The method was validated by demonstrating fluid delivery principles and obtaining a continuous electrospray spectrum of tetrabutylammonium iodide coupled to an ion trap mass spectrometer.

Abstract

A method of generating electrospray from solutions emerging from small channels etched on planar substrates is described. The fluids are delivered using electroosmotically induced pressures and are sprayed electrostatically from the terminus of a channel by applying an electrical potential of sufficient amplitude to generate the electrospray between the microchip and a conductor spaced from the channel terminus. No major modification of the microchip is required other than to expose a channel opening. The principles that regulate the fluid delivery are described and demonstrated. A spectrum for a test compound, tetrabutylammonium iodide, that was continuously electrophoresed was obtained by coupling the microchip to an ion trap mass spectrometer.