Electrospray ion source assembly

An electrospray ion source assembly for use in a mass spectrometry system, comprising:

• a housing defining an ionization chamber configured to be disposed in fluid communication with a sampling orifice of a mass spectrometer system, the housing providing at least a first opening configured for coupling to a first electrospray probe, the first electrospray probe configured to discharge a liquid sample into the ionization chamber at sample flow rates greater than a nanoflow range such that the discharged liquid forms a sample plume comprising a plurality of sample droplets, wherein the first opening of the housing and the first electrospray probe are configured such that a longitudinal axis of the first electrospray probe is substantially orthogonal to a central axis of the sampling orifice, wherein the first electrospray probe is separated from the central axis of the sampling orifice along the longitudinal axis of the first electrospray probe by a first distance;
• and
• an elongate auxiliary electrode assembly extending from the housing to an electrically conductive distal end disposed in the ionization chamber, the electrically conductive distal end being offset from the central axis of the sampling orifice such that a second distance from the electrically conductive distal end to the central axis of the sampling orifice, in a direction of the central axis of the sampling orifice, is in a range of about 5% of the first distance to about 70% of the first distance, and the electrically conductive distal end configured to couple to a power supply so as to generate an electric field within the ionization chamber to improve the desolvation of the sample plume and the transport of ions ejected from the sample plume into the sampling orifice.