Ion generation using wetted porous material
The invention generally relates to systems and methods for mass spectrometry analysis of samples. In certain embodiments, the invention provides a mass spectrometry probe including at least one porous material connected to a high voltage source, in which the porous material is discrete from a flow of solvent.
1. A method for analyzing a food or beverage sample, the method comprising:
introducing a food or beverage sample to a probe comprising at least one porous material that tapers to at least one tip, wherein the probe operates without pneumatic assistance;
applying a high voltage to the porous material such that an electric field is generated at a tip of the material so as to generate ions of an analyte in the sample that are expelled from the tip of the porous material; and
analyzing the expelled ions, thereby analyzing the food or beverage sample.
2. The method according to claim 1 , further comprising applying a solvent to the porous material.
3. The method according to claim 2 , wherein the porous material is kept separate from a flow of solvent.
4. The method according to claim 2 , wherein the solvent assists transport of the sample through the porous material.
5. The method according to claim 2 , wherein the solvent contains an internal standard.
6. The method according to claim 2 , wherein the solvent allows for differential retention of sample components with different chemical properties.
7. The method according to claim 2 , wherein the solvent minimizes salt and matrix effects.
8. The method according to claim 2 , wherein the solvent allows for on-line chemical derivatization of selected analytes.
9. The method according to claim 1 , wherein the food sample comprises fruit.
10. The method according to claim 1 , wherein the food sample comprises coffee.
11. The method according to claim 1 , wherein the beverage sample comprises soda.
12. The method according to claim 1 , wherein the porous material is paper or PVDF membrane.
13. The method according to claim 12 , wherein the paper is filter paper.
14. The method according to claim 13 , wherein the filter paper is shaped to have a side that terminates in a point.
15. The method according to claim 14 , wherein the filter paper has a triangular shape.
16. The method according to claim 1 , wherein analyzing comprises providing a mass analyzer to generate a mass spectrum of analytes in the sample.
17. The method according to claim 16 , wherein the mass analyzer situated within a miniature mass spectrometer.
18. The method according to claim 17 , wherein the mass analyzer is selected from the group consisting of: a quadrupole ion trap, a rectilinear ion trap, a cylindrical ion trap, a ion cyclotron resonance trap, and an orbitrap.
19. The method according to claim 1 , wherein an electric field generated by the high voltage assists in transport of the sample through the porous material.
20. The method according to claim 1 , wherein the solvent forms a thin liquid film over the surface of the porous material.
21. The method according to claim 20 , wherein an electric field generated by the high voltage assists in transport of the analytes in the thin liquid film.
22. A method for analyzing a food or beverage sample, the method comprising:
obtaining a food or beverage sample;
introducing at least a portion of the food or beverage sample to a probe comprising at least one porous material, wherein the probe operates without pneumatic assistance and the introducing step is without any sample preparation steps;
applying a high voltage to the porous material such that an electric field is generated at a tip of the material so as to generate ions of an analyte in the sample that are expelled from the porous material; and
analyzing the expelled ions, thereby analyzing the food or beverage sample.