Ion trap mass spectrometer with vacuum-external ion generation
AssigneeBruker-Franzen Analytik GmbH
InventorJochen Franzen
Life of this patent
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Abstract
The invention relates to an RF quadrupole ion trap mass spectrometer with ionization of the substance molecules outside the vacuum system. The invention consists of using only a single high-vacuum pump for generating the vacuum without any differential pump stages and generating the necessary pressure stages for operating the mass spectrometer by means of a sequence of openings with adjusted conductances. The necessarily very small inlet opening to the vacuum system is only able to transport very small quantities of ions of the analyzed substances in the gas stream. However, these quantities are adequate for operating the mass spectrometer because the ion trap used as mass spectrometer is capable of collecting and storing ions over relatively long periods of time.
Claims10
Ion trap mass spectrometer comprising:
- (a) an RF quadrupole ion trap with ion injection and ejection openings,
- (b) an ion detector outside the ion trap for measuring ions ejected from the ion trap through the ejection opening,
- (c) a vacuum system which encompasses the ion trap and ion detector, the vacuum system comprising a plurality of interconnected vacuum chambers including a first chamber containing the ion trap and a second chamber containing the ion detector,
- (d) an ion source outside the vacuum system, and
- (e) a capillary inlet opening in the wall of the vacuum system for admitting a gas stream, with which the ions are transported into the vacuum system, and wherein
- (f) the vacuum within the vacuum system is generated by only a single high vacuum pump, the vacuum pump having a suction capacity of less than 100 liters per second, and the only gas intake of the vacuum system is through the capillary inlet opening,
- (g) the ion detector is installed near the port of the high vacuum pump, and
- (h) the capillary inlet opening, and openings between the chambers of the vacuum system are dimensioned so that a vacuum in the second chamber is maintained at or below 10.sup.-4 millibar, and a vacuum in the first chamber is significantly different than that of the second chamber, and maintained above 10.sup.-4 millibar.
Dependencies are inferred from the claim text.