Apparatus and method for thermal assisted desorption ionization systems
The present invention is directed to a method and device to desorb an analyte using heat to allow desorption of the analyte molecules, where the desorbed analyte molecules are ionized with ambient temperature ionizing species. In various embodiments of the invention a current is passed through a mesh upon which the analyte molecules are present. The current heats the mesh and results in desorption of the analyte molecules which then interact with gas phase metastable neutral molecules or atoms to form analyte ions characteristic of the analyte molecules.
1. A device for identifying substances comprising:
a spectrometer configured for analyzing an analyte, with an entrance for accepting one or more analyte ions and a detector for detecting analyzed analyte ions;
an atmospheric pressure source configured for generating ionizing species;
a mesh positioned between the atmospheric pressure source and the spectrometer; and
a supply adapted to periodically heat the mesh, where the analyte is introduced on or near the mesh, where one or more analyte molecules desorbed from the mesh interact with the ionizing species generated by the atmospheric pressure source to form the one or more analyte ions which enter the spectrometer and are analyzed.
2. The device of claim 1 , further comprising a gas ion separator positioned between the mesh and the entrance.
3. The device of claim 1 , where the atmospheric pressure source is selected from the group of sources consisting of a direct analysis real time (DART), Plasma Assisted Desorption/Ionization (PADI), Dielectric Barrier Discharge ionization source (DBDI or DCBI), Desorption Atmospheric Pressure Chemical Ionization (DAPCI), Desorption Sonic Spray Ionization (DeSSI), Desorption Atmospheric Pressure Photoionization (DAPPI), and Flowing Atmospheric- Pressure Afterglow (PAPA) and a desorption electrospray ionization (DESI), an atmospheric laser desorption ionization, a Corona discharge, an inductively coupled plasma (ICP) and a glow discharge source.
4. The device of claim 1 , where the supply is adapted to deliver a power to the mesh of between:
a lower limit of approximately 10 2 Watts; and
an upper limit of approximately 10 3 Watts.
5. The device of claim 1 , where a region between the entrance and the detector of the spectrometer is at approximately atmospheric pressure.
6. The device of claim 1 , where a region between a distal end of the atmospheric pressure source and the entrance of the spectrometer is at approximately atmospheric pressure.
7. The device of claim 1 , where the supply is adapted to apply a first potential to the mesh.
8. The device of claim 7 , where the first potential is approximately equal to a potential applied to the entrance to the spectrometer.
9. The device of claim 7 , where the supply is further adapted to allow adjustment of the first potential.
10. The device of claim 1 , where the supply is configured to independently heat a first location and a second location on the mesh, where the first location is different than the second location.
11. The device of claim 1 , where the mesh is adapted to hold, wrap or otherwise attached to the analyte.
12. The device of claim 1 , where the mesh comprises two or more connected filaments, where one or more of the two or more connected filaments are selected from the group consisting of a metal, an animal string, paper, perforated paper, fiber, cloth, silica, plastic, plastic foam, polymer, teflon, polymer impregnated teflon, cellulose, hydrophobic support material coated filament and hydrophobic support material impregnated filament.
13. The device of claim 1 , where the spectrometer is an ion mobility spectrometer.
14. The device of claim 13 , where the ion mobility spectrometer is operated at approximately atmospheric pressure.
15. The device of claim 1 , where the spectrometer is a mass spectrometer.
16. The device of claim 15 , where the mass spectrometer is selected from the group consisting of a quadrupole, a quadrupole ion trap, a rectilinear ion trap, a cylindrical ion trap, a ion cyclotron resonance trap, an orbitrap, a time of flight and a sector mass spectrometer.