An electrospray probe for use in an electrospray ion source is disclosed, which comprises a cannula extending from a proximal end having an inlet aperture for receiving a liquid sample containing at least one analyte to a discharge emitter end having an outlet aperture through which charged liquid droplets containing ions of said analyte are discharged, and an electrically conductive coating covering at least a portion of an external surface and at least a portion of an internal surface of said emitter end.