Abstract: An ion source for use with an ion trap mass spectrometer. The ion source includes an electron source which produces a stream of electrons. The electrons are injected into an ionization chamber by the action of a repeller plate and electron lens. Inside the ionization chamber, the electrons interact with a gas-phase sample to produce sample ions through the electron ionization process, or with a reagent gas to form reagent ions as part of a chemical ionization process. The sample ions produced are extracted from the ionization chamber by the action of an ion repeller and an ion lens. The potentials on the electron repeller and lens, and ion repeller and lens are controlled to direct the electron stream away from the ionization chamber or to direct the sample ion beam away from an ion trap at the appropriate times during measurement of the sample ions.

Abstract: An apparatus for electrospray ionization of a liquid sample matrix to prepare the sample for introduction into a mass spectrometer. The inventive electrospray interface is arranged between a source of a liquid sample matrix and an electrospray ionization needle. The interface includes a central chamber which contains elements for passively mixing the liquid sample flow with a modifying liquid added to the central chamber through a side channel. The side channel is isolated from the central chamber by a flow restrictor and the modifying liquid is provided to the side channel through a valve. A second valve, side channel, and flow restrictor are used to permit introduction of a calibration fluid into the central chamber through the first side channel. The inventive interface permits mixing of a modifying liquid with the liquid sample matrix to assist in nebulization of the liquid sample by reducing the surface tension of the sample containing fluid.

Abstract: An apparatus for producing gas-phase ions from a sample compound in a carrier liquid. The electrospray needle (or capillary) of the present invention includes a central metal tube which carries the liquid containing the sample compound. The central tube is surrounded by a plurality of tubes which transport a nebulizing gas. The nebulizing gas tubes are placed symmetrically around the outside of the liquid containing tube. The nebulizer of the present invention produces a symmetric, non-annular gas flow which has variations in pressure around the circumference of the central tube. The pressure variations of the nebulizing gas flow produce additional shear forces on the liquid emerging from the central tube. This assists in forming a uniform electrospray of droplets from the liquid at lower nebulizing gas flow rates, thereby reducing the disadvantageous effects of the higher gas flow rates used in the art.

Abstract: An apparatus for efficiently removing a carrier liquid from charged liquid drops formed by electrospray ionization prior to introduction of the drops into a mass spectrometer. A central capillary tube connects a region of the low pressure vacuum system containing the mass spectrometer with a region at substantially atmospheric pressure, in which ion formation is produced by electrospray ionization. Heated, drying gas flows through a plurality of vortex forming channels symmetrically disposed about the axis of the central capillary tube which provides an entrance to the spectrometer. Gas exiting the vortex forming channels enters tangentially to the inside of a vortex drying tube with a small helix angle, causing the gas to swirl around the tube, forming a vortex. The vortex drying gas flows in a direction that is substantially transverse to the axis of the entrance capillary into the mass spectrometer.