Patent ID: 8546753

Claim:
An electrospray ion source apparatus for generating ions from a liquid sample for introduction into a mass spectrometer comprising: a plurality of emitter capillaries, each comprising: an internal bore for transporting a portion of the liquid sample from a source; an electrode portion for providing a first applied electric potential; and an emitter tip for emitting a cloud of charged particles generated from the liquid sample portion; a counter electrode for providing a second applied electric potential different from the first applied electric potential; and at least one shield electrode disposed at least partially between the counter electrode and the emitter tip of at least one of the emitter capillaries for providing a third applied electric potential intermediate to the first and second applied electric potentials, wherein the at least one shield electrode is configured such that provision of the third applied electric potential to the at least one shield electrode minimizes electric field interference effects between the plurality of emitter capillaries.