# US 2019/0355567 A1 · Mass spectrometry probes and systems for ionizing a sample > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0355567 A1 - Document ID: US20190355567A1 - Status: Published application - Kind: A1 - Application number: 16/516,823 - Filed: 2019-07-19 - Published: 2019-11-21 - Earliest claimed: 2013-12-30 - Assignees: Purdue Research Foundation - Applicants: Purdue Research Foundation - Inventors: Robert Graham Cooks; Depanjan Sarkar; Thalappil Pradeep; Rahul Narayanan - Web page: https://patentgrep.com/patent/US20190355567A1 ## CPC - H01J 49/165: {Electrospray ionisation} - H01J 49/0409: {Sample holders or containers (containers for retaining a material to be analyzed, B01L3/50, for DNA, C12Q1/6834, for biological materials, G01N33/543)} - H01J 49/0431: {for liquid samples (interfaces to liquid chromatographs G01N30/7233)} - H01J 49/16: using surface ionisation, e.g. field-, thermionic- or photo-emission - H05K 1/18: structurally associated with non-printed electric components (H05K1/16 takes precedence) - H01J 49/0013: {Miniaturised spectrometers, e.g. having smaller than usual scale, integrated conventional components} - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) - H05K: PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS ## Abstract The invention generally relates to mass spectrometry probes and systems for ionizing a sample. In certain embodiments, the invention provides a mass spectrometry probe including a substrate in which a portion of the substrate is coated with a material, a portion of which protrudes from the substrate. ## Claims ### Claim at position 1 1-20. (canceled) ### Claim 21 A method for analyzing a sample, the method comprising: providing a mass spectrometry probe comprising a paper substrate in which a portion of the paper substrate is coated with an electrically conductive material that is not a sample or a solvent, in a manner that a plurality of nanoscale features protrude from the paper substrate, the plurality of nanoscale features configured to act as a plurality of electrodes and upon application of a voltage of 3 volts or less, providing a field strength high enough to cause field emission of microscale solution droplets at the plurality of nanoscale features at a voltage that does not cause fragmentation of the analyte; connecting the mass spectrometry probe to a voltage source, wherein the voltage source is configured to generate a voltage of 3 volts or less; contacting the mass spectrometry probe with a sample; ionizing the sample that has contacted the mass spectrometry probe; and analyzing the ionized sample in a mass spectrometer. ### Claim 22 (depends on 21) The method according to claim 21, wherein the electrically conductive material comprises one or more electrically conductive nanotubes. ### Claim 23 (depends on 23) The method according to claim 23, wherein the electrically conductive nanotubes are carbon nanotubes. ### Claim 24 (depends on 23) The method according to claim 23, wherein the carbon nanotubes coat an external surface of the paper substrate. ### Claim 25 (depends on 21) The method according to claim 21, wherein prior to the ionizing step, the method further comprises applying a solvent to the mass spectrometry probe. ### Claim 26 (depends on 25) The method according to claim 25, wherein the solvent is continuously supplied to the mass spectrometry probe. ### Claim 27 (depends on 25) The method according to claim 25, wherein the mass spectrometry probe is separate from the solvent. ### Claim 28 (depends on 25) The method according to claim 25, wherein the solvent assists in at least one of separation, extraction, and ionization of the sample. ### Claim 29 (depends on 21) The method according to claim 21, wherein pneumatic assistance is not required to transport the sample through the mass spectrometry probe. ### Claim 30 (depends on 21) The method according to claim 21, wherein the paper is filter paper. ### Claim 31 A method for analyzing a sample, the method comprising: providing a mass spectrometry probe comprising a paper substrate and a plurality of carbon nanotubes, the mass spectrometry probe configured such that a portion of each of the plurality of carbon nanotubes protrudes from the paper substrate forming a plurality of nanoscale features that extend from the paper substrate, the plurality of nanoscale features configured to act as a plurality of electrodes and upon application of a voltage of 3 volts or less, providing a filed strength high enough to cause field emission of microscale solution droplets at a voltage that does not cause fragmentation of the analyte; connecting the mass spectrometry probe to a voltage source, wherein the voltage source is configured to generate a voltage of 3 volts or less; contacting the mass spectrometry probe with a sample; ionizing the sample that has contacted the mass spectrometry probe; and analyzing the ionized sample in a mass spectrometer. ### Claim 32 (depends on 31) The method according to claim 31, wherein the carbon nanotubes coat an external surface of the paper substrate. ### Claim 33 (depends on 31) The method according to claim 31, wherein prior to the ionizing step, the method further comprises applying a solvent to the mass spectrometry probe. ### Claim 34 (depends on 33) The method according to claim 33, wherein the solvent is continuously supplied to the mass spectrometry probe. ### Claim 35 (depends on 33) The method according to claim 33, wherein the mass spectrometry probe is separate from the solvent. ### Claim 36 (depends on 33) The method according to claim 33, wherein the solvent assists in at least one of separation, extraction, and ionization of the sample. ### Claim 37 (depends on 31) The method according to claim 31, wherein pneumatic assistance is not required to transport the sample through the mass spectrometry probe. ### Claim 38 (depends on 31) The method according to claim 31, wherein the paper is filter paper. ### Claim 39 (depends on 38) The method according to claim 38, wherein the filter paper comprises a pointed tip. ### Claim 40 (depends on 38) The method according to claim 38, wherein the filter paper does not comprise a pointed tip.