Low-pressure electron ionization and chemical ionization for mass spectrometry
AssigneeAgilent Technologies, Inc.
InventorGregory J. Wells
Life of this patent
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Abstract
A sample is ionized by chemical ionization by flowing the sample and a reagent gas into an ion source at a pressure below 0.1 Torr. While maintaining the ion source at a pressure below 0.1 Torr, the reagent gas is ionized in the ion source by electron ionization to produce reagent ions. The sample is reacted with the reagent ions at a pressure below 0.1 Torr to produce product ions of the sample. The product ions are transmitted into an ion trap for mass analysis.
Claims18
A method for ionizing a sample by chemical ionization, the method comprising:
- flowing the sample and a reagent gas into an ion source at a pressure below 0.1 Torr;
- while maintaining the ion source at the pressure below 0.1 Torr, ionizing the reagent gas in the ion source by electron ionization to produce reagent ions;
- transmitting the reagent ions into an ion guide;
- flowing the sample from the ion source into the ion guide;
- reacting the sample with the reagent ions in the ion guide at a pressure below 0.1 Torr to produce product ions of the sample;
- and
- transmitting the product ions into an ion trap for mass analysis.
A method for operating an ion source, the method comprising:
- ionizing a first sample in the ion source by electron ionization to produce first sample ions, while maintaining the ion source at a pressure below 0.1 Torr;
- transmitting the first sample ions to an ion trap for mass analysis;
- while continuing to maintain the ion source at a pressure below 0.1 Torr, flowing a reagent gas and a second sample into the ion source;
- ionizing the reagent gas in the ion source by electron ionization to produce reagent ions;
- transmitting the reagent ions into an ion guide;
- flowing the second sample from the ion source into the ion guide;
- reacting the second sample with the reagent ions in the ion guide at a pressure below 0.1 Torr to produce product ions of the second sample;
- and
- transmitting the product ions into the ion trap for mass analysis.
A mass spectrometry apparatus, comprising:
- an ion source comprising an ionization chamber and an electron source configured for directing an electron beam into the ionization chamber, the ionization chamber having one or more inlets for receiving a sample and reagent gas;
- a vacuum pump configured for maintaining a pressure below 0.1 Torr in the ionization chamber;
- an ion guide comprising a plurality of guide electrodes surrounding an ion guide interior space communicating with the ionization chamber, and configured for applying an RF ion-trapping electric field;
- first ion optics interposed between the ion source and the ion guide and configured for applying an electric potential barrier;
- an ion trap comprising a plurality of trap electrodes surrounding an ion trap interior space communicating with the ion guide interior space, and configured for mass-analyzing ions;
- and
- second ion optics interposed between the ion guide and the ion trap and configured for applying an electric potential barrier.
Dependencies are inferred from the claim text.