Method and apparatus for ionization of a sample at atmospheric pressure using a laser
A method for ionizing a sample at ambient pressure including providing ionization-assisting molecules on a surface of a substrate, placing sample molecules on the surface of the substrate, and irradiating at least one of the sample molecules and the ionization-assisting molecules to produce ions of the sample molecules at or near atmospheric pressure. Accordingly, the system for ionizing sample molecules at or near atmospheric pressure is disclosed.
1 . A method for ionizing sample molecules from a substrate, comprising:
providing on a surface of said substrate ionization-assisting molecules;
placing sample molecules on said surface; and
irradiating at least one of the sample molecules and the ionization-assisting molecules to produce ions of said sample molecules at or near atmospheric pressure.
2 . The method as in claim 1 , wherein the step of providing comprises:
using as said substrate a porous substrate.
3 . The method as in claim 1 , wherein the step of providing comprises:
using as said substrate a gel.
4 . The method as in claim 1 , wherein the step of providing comprises:
using as said substrate a polyacrylamide gel.
5 . The method as in claim 1 , wherein the step of providing comprises:
modifying said surface by a derivitization that bonds said ionization-assisting molecules covalently to said surface.
6 . The method as in claim 1 , wherein the step of providing comprises:
modifying said surface by a derivitization that bonds said ionization-assisting molecules non-covalently to said surface.
7 . The method as in claim 1 , wherein the step of providing comprises:
attaching a monolayer of said ionization-assisting molecules to said surface.
8 . The method as in claim 1 , wherein the step of providing comprises:
attaching multiple layers of said ionization-assisting molecules to said surface.
9 . The method as in claim 1 , wherein the step of providing comprises:
attaching said ionization-assisting molecules to said surface such that said ionization-assisting molecules are immobilized on said surface.
10 . The method as in claim 1 , wherein the step of providing comprises:
attaching at least one of α-cyano-4-hydroxycinnamic acid, dihydrobensoic acid, cinapinic acid, nicotinic acid, succinic acid, picolinic acid, and 3-hydroxy-picolinic acid to said surface.
11 . The method as in claim 1 , wherein the step of providing comprises:
attaching said ionization-assisting molecules that absorb at a wavelength of said laser.
12 . The method as in claim 1 , wherein the step of placing comprises:
depositing the sample molecules dissolved in at least one solvent; and
evaporating said at least one solvent.
13 . The method as in claim 1 , wherein the step of placing comprises:
attaching of said sample molecules to said surface using affinity techniques.
14 . The method as in claim 1 , wherein the step of placing comprises:
placing as said sample molecules at least one of peptides, proteins, ribonucleic acid, deoxyribonucleic acids, and carbohydrates.
15 . The method as in claim 1 , wherein the step of irradiating comprises:
irradiating with a pulsed laser.
16 . The method as in claim 14 , wherein the step of irradiating with a pulsed laser comprises:
irradiating with a laser pulse duration with a range of 1-100 nsec.
17 . The method as in claim 1 , wherein the step of irradiating comprises:
irradiating with a continuous laser.
18 . The method as in claim 1 , wherein the step of irradiating comprises:
irradiating with a laser of a wavelength of at least one of about 266 nm, 337 nm, 355 nm, or 3 μm.
19 . The method as in claim 1 , wherein the step of irradiating comprises:
irradiating with a laser of a range of 50-200 μJ/pulse energy.
20 . The method as in claim 18 , wherein the step of irradiating comprises:
irradiating with a laser concentrated to an elliptical spot of 400×600 μm.
21 . The method as in claim 1 , further comprising:
transporting said ions toward an inlet orifice of a mass spectrometer.
22 . The method as in claim 20 , wherein said transporting comprises:
drifting said ions toward the inlet orifice of the mass spectrometer by an electric field.
23 . The method as in claim 21 , wherein said transporting comprises:
entraining said ions in a gas flowing into said mass spectrometer via said orifice.
24 . A system for ionizing sample molecules, comprising:
a substrate;
ionization-assisting molecules on said substrate;
said sample molecules adjacent said ionization-assisting molecules; and
an irradiating device configured to irradiate at or near atmospheric pressure at least one of the sample molecules and the ionization-assisting molecules.
25 . The system of claim 24 , wherein said substrate comprises:
a porous substrate.
26 . The system of claim 24 , wherein said substrate comprises:
a gel.
27 . The system of claim 24 , wherein said substrate comprises:
a polyacrylamide gel.
28 . The system of claim 24 , wherein said substrate comprises:
a derivitized surface that bonds said ionization-assisting molecules covalently to said surface.
29 . The system of claim 24 , wherein said substrate comprises:
a derivitized surface that bonds said ionization-assisting molecules non-covalently to said substrate.
30 . The system of claim 24 , wherein said substrate comprises:
a monolayer of said ionization-assisting molecules attached to a surface of said substrate.
31 . The system of claim 24 , wherein said substrate comprises:
multiple layers of said ionization-assisting molecules attached to a surface of said surface.
32 . The system of claim 24 , wherein said substrate comprises:
an immobilized surface of said ionization-assisting molecules attached to a surface of said substrate.
33 . The system of claim 24 , wherein said substrate comprises:
a layer of at least one of α-cyano-4-hydroxycinnamic acid, dihydrobensoic acid, cinapinic acid, nicotinic acid, succinic acid, picolinic acid, and 3-hydroxy-picolinic acid attached to a surface of said surface as said ionization-assisting molecules.
34 . The system of claim 24 , wherein said irradiating device comprises:
a pulsed laser.
35 . The system of claim 24 , wherein said irradiating device comprises:
a laser pulse duration with a range of 1-100 nsec.
36 . The system of claim 24 , wherein said irradiating device comprises:
a continuous laser.
37 . The system of claim 24 , wherein said irradiating device comprises:
a laser of a wavelength of at least one of about 266 nm, 337 nm, 355 nm, or 3 μm.
38 . The system of claim 24 , wherein said irradiating device comprises:
a laser having a range of 50-200 μJ/pulse energy.
39 . The system of claim 38 , wherein said irradiating device is configured to irradiate an elliptical spot of 400×600 μm.
40 . The system of claim 24 , further comprising:
a mass spectrometer having an orifice to collect said ions for mass analysis.
41 . The system of claim 40 , further comprising:
a housing enclosing the substrate and providing a gas purge to a region of the substrate and the mass spectrometer.
42 . The system of claim 24 , wherein said sample molecules comprise at least one of peptides, proteins, ribonucleic acid, deoxyribonucleic acids, and carbohydrates.