Patent ID: 7199364

Claim:
Apparatus for forming ions in a mass analyzing system from a liquid sample including an analyte and a solvent, comprising: an ionization chamber; a capillary tube having a free end for directing the liquid sample as a spray of droplets into the ionization chamber, at least a portion of the capillary tube being maintained at a potential relative to another surface in the ionization chamber such that the droplets are electrically charged; a first gas passageway for directing a first gas stream into the ionization chamber through an annular first end region circumferentially proximate to the free end of capillary tube, the first gas stream having a first major axis; a second gas passageway for directing a second gas stream into the ionization chamber through a second end region disposed more remotely from the free end of the capillary tube relative to the first end region, the second gas stream being co-directional with the first gas stream and having a second major axis substantially parallel to the first major axis, the second gas stream being heated to assist in the evaporation of the solvent from the droplets to form ions of the analyte, the second gas stream being insulated from the first gas stream by at least one insulative barrier between the first and second gas streams; and an ion sampling pathway opening to the ionization chamber for guiding the ions toward a mass analyzer.