Electrospray method for mass spectrometry

Claim 1

Apparatus for converting a liquid effluent including sample solute of interest and solvent into ionized molecules for analysis of the sample by a mass spectrometer, the apparatus comprising: (a) an electrospray unit for receiving liquid effluent and for discharging charged droplets, the electrospray unit including (i) an electrospray housing defining an atmospheric pressure electrospray chamber therein, (ii) a capillary tube for passing liquid effluent therethrough, the capillary tube having an exit within the electrospray chamber for discharging sprayed droplets containing sample solute of interest and solvent, (iii) a high voltage source for applying a high voltage to the capillary tube to produce charged sprayed droplets containing sample solute of interest and solvent, the charged sprayed droplets vaporizing within the electrospray housing to produce ions, and (iv) a nozzle defining a portion of the electrospray housing and having a discharge port for outputting the ions and solvent vapor from the electrospray chamber, the discharge port being sized to maintain substantially atmospheric pressure within the electrospray chamber during spraying; (v) a first electrical biasing unit for applying a biasing voltage to the nozzle; and (b) an ion generating unit for receiving clusters of ions including condensed solvent from the electrospray unit and for discharging ionized molecules to the mass spectrometer, the ion generating unit including (i) an ion generating housing defining an ion generating chamber therein, (ii) an ion generating unit vacuum pump for maintaining pressure within the ion generating chamber in the range of from 0.1 Torr to 10 Torr, (iii) a temperature sensor for monitoring the temperature within the ion generating chamber, (iv) a heating unit responsive to the temperature sensor for heating the ion generating housing to a temperature of at least 120° C. to vaporize condensed solvent in the clusters of ions and produce desolvated ionized molecules of interest for analysis by the mass spectrometer, (v) a sampling cone having passage therethrough for discharging ionized molecules from the ion generating chamber, and (vi) a second electrical biasing unit for applying a biasing voltage to the sampling cone relative to the nozzle of the electrospray unit.

Claim 12

A method of converting a liquid effluent including sample solute of interest and solvent into ionized molecules for analysis by a mass spectrometer, the method comprising: forming an electrospray chamber having a restricted discharge port therethrough; passing liquid effluent through a capillary tube terminating within the electrospray chamber for discharging sprayed droplets containing sample solute of interest and solvent; applying a voltage to the capillary tube to produce charged sprayed droplets containing sample solute of interest and solvent; maintaining the electrospray chamber at substantially atmospheric pressure or above during spraying; applying a first biasing voltage during spraying to at least a portion of an electrospray housing which defines the restricted discharge port; forming in an ion generating housing which defines an ion generating chamber; passing the charged sprayed droplets into the ion generating chamber while maintaining a pressure within the ion generating chamber within the range of from 0.1 Torr to 10 Torr; monitoring the temperature within the ion generating chamber: heating the ion generating housing in response to the monitored temperature to vaporize solvent in clusters of ions and produce desolvated ionized molecules of interest for analysis by the mass spectrometer; applying a second biasing voltage to a skimmer relative to the portion of the electrospray housing and outputting the desolvated ions through the skimmer to the mass spectrometer.

Claim 13

A method of converting a liquid effluent including sample solute of interest and solvent into ionized molecules for analysis by a mass spectrometer, the method comprising: forming an electrospray chamber having a restricted discharge port therethrough; passing liquid effluent through a capillary tube terminating within the electrospray chamber for discharging sprayed droplets containing sample solute of interest and solvent; applying a voltage to the capillary tube to produce charged sprayed droplets containing sample solute of interest and solvent; maintaining the electrospray chamber at substantially atmospheric pressure or above during spraying; applying a first biasing voltage during spraying to at least a portion of an electrospray housing which defines the restricted discharge port; forming in an ion generating housing which defines an ion generating chamber; passing the charged sprayed droplets into the ion generating chamber while maintaining a pressure within the ion generating chamber within the range of from 0.1 Torr to 10 Torr; monitoring the temperature within the ion generating chamber: heating the ion generating housing in response to the monitored temperature to vaporize solvent in clusters of ions and produce desolvated ionized molecules of interest for analysis by the mass spectrometer; applying a second biasing voltage to a skimmer relative to the portion of the electrospray housing and outputting the desolvated ions through the skimmer to the mass spectrometer.