Systems and methods for separating ions at about or above atmospheric pressure
The invention generally relates to systems and methods for separating ions at about or above atmospheric pressure. In certain embodiments, the invention provides systems that include an ionization source that generates ions and an ion trap. The ion trap is maintained at about or above atmospheric pressure and includes a plurality of electrodes and at least one inlet configured to receive a gas flow and at least one outlet. The system is configured such that a combination of a gas flow and one or more electric fields produced by the electrodes separates the ions based on mass-to-charge ratio and sends the separated ions through the at least one outlet of the ion trap.
1. A system for separating ions, the system comprising:
an ionization source that generates ions; and
an ion trap maintained at about or above atmospheric pressure that comprises a plurality of electrodes and at least one inlet configured to receive a gas flow and at least one outlet, wherein the plurality of electrodes are arranged such that an exit point exists between the plurality of electrodes and ions excited by the plurality of electrodes pass through the exit point and become entrained in a gas flow that passes along an exterior of the plurality of electrodes toward the at least one outlet;
wherein the system is configured such that a combination of the gas flow and one or more frequency components of the electric field produced by the electrodes separates the ions based on mass-to-charge ratio and sends the separated ions through the at least one outlet of the ion trap.
2. The system according to claim 1 , further comprising a gas source operably coupled to the at least one inlet.
3. The system according to claim 1 , further comprising an ion detector configured to receive the separated ions.
4. The system according to claim 3 , further comprising an ion focusing element positioned between the ion trap and the ion detector.
5. The system according to claim 3 , wherein the ion detector is a mass spectrometer.
6. The system according to claim 5 , wherein the mass spectrometer is a miniature mass spectrometer that does not include a vacuum system.
7. A method for separating ions at about or above atmospheric pressure, the method comprising:
trapping ions within an ion trap at about or above atmospheric pressure, wherein the ion trap comprises a plurality of electrodes and at least one inlet configured to receive a gas flow and at least one outlet, wherein the plurality of electrodes are arranged such that an exit point exists between the plurality of electrodes and ions excited by the plurality of electrodes pass through the exit point and become entrained in a gas flow that passes along an exterior of the plurality of electrodes toward the at least one outlet; and
applying an electric field and the gas flow to the ions within the ion trap at about or above atmospheric pressure to separate the ions by mass-to-charge ratio.
8. The method according to claim 7 , wherein ions of particular mass-to-charge ratios are separated from remaining trapped ions and directed into the gas flow thereby separating the ions by mass-to-charge ratio.
9. The method according to claim 8 , further comprising analyzing the ions separated by mass-to-charge ratio.
10. The method according to claim 9 , wherein analyzing comprises directing the ions into a mass spectrometer.
11. The method according to claim 10 , wherein the mass spectrometer is operated at about or above atmospheric pressure.
12. The method according to claim 7 , wherein the electric field comprises frequency components that correspond to characteristic frequencies of motion of at least some of the trapped ions, and the frequency components of the electric field can be varied so as to select any ions of any desired mass-to-charge or group of mass-to-charge values.