# US 2021/0280408 A1 · Impact ionisation ion source > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2021/0280408 A1 - Document ID: US20210280408A1 - Status: Published application - Kind: A1 - Application number: 17/259,482 - Filed: 2019-07-04 - Published: 2021-09-09 - Earliest claimed: 2018-07-11 - Assignees: Micromass UK Limited - Applicants: Micromass UK Limited - Inventors: Stevan Bajic; Jeffery Mark Brown - Web page: https://patentgrep.com/patent/US20210280408A1 ## CPC - H01J 49/165: {Electrospray ionisation} - H01J 49/0072: {by ion/ion reaction, e.g. electron transfer dissociation, proton transfer dissociation} - H01J 49/045: {with means for using a nebulising gas, i.e. pneumatically assisted} - H01J 49/16: using surface ionisation, e.g. field-, thermionic- or photo-emission - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract An ion source is provided comprising a nebuliser or electrospray probe (1) for nebulising a sample and an impact surface or target electrode (5). The impact surface or target electrode (5) comprises a tarnishable or oxidisable metal or an alloy comprising tarnishable or oxidisable metal. Also provided is an ion source comprising a nebuliser or electrospray probe with a central wire comprising a tarnishable or oxidisable metal or an alloy comprising a tarnishable or oxidisable metal or an alloy comprising a tarnishable or oxidisable metal. Adducts with relatively heavy metals result in simplified multiply-charged mass spectra that are easier to interpret. ## Claims ### Claim 1 An ion source comprising: a nebuliser or electrospray probe for nebulising a sample; and an impact surface or target electrode, wherein the impact surface or target electrode comprises a tarnishable or oxidisable metal or an alloy comprising a tarnishable or oxidisable metal. ### Claim 2 (depends on 1) An ion source as claimed in claim 1, wherein the tarnishable or oxidisable metal or alloy comprising a tarnishable or oxidisable metal has an electronegativity>1.50. ### Claim 3 (depends on 1) An ion source as claimed in claim 1, wherein the tarnishable or oxidisable metal or alloy comprising a tarnishable or oxidisable metal has a melting point<1500 K, <1450 K, <1400 K, <1350 K, <1300 K, <1250 K, <1200 K, <1150 K, <1100 K, <1050 K or <1000K. ### Claim 4 (depends on 1) An ion source as claimed in claim 1, wherein the tarnishable or oxidisable metal or alloy comprising a tarnishable or oxidisable metal has a melting point >400 K, >410 K, >420 K, >430 K, >440 K, >450 K, >460 K, >470 K, >480 K, >490 K or >500 K. ### Claim 5 (depends on 1) An ion source as claimed in claim 1, wherein the tarnishable or oxidisable metal or alloy comprising a tarnishable or oxidisable metal has a hardness<2.0 Mohs. ### Claim 6 (depends on 1) An ion source as claimed in claim 1, wherein the tarnishable or oxidisable metal or alloy comprising a tarnishable or oxidisable metal comprises a post-transition metal. ### Claim 7 (depends on 6) An ion source as claimed in claim 6, wherein the post-transition metal comprises gallium (Ga), indium (In), tin (Sn), lead (Pb) or bismuth (Bi). ### Claim 8 (depends on 1) An ion source as claimed in claim 1, wherein the tarnishable or oxidisable metal or alloy comprising a tarnishable or oxidisable metal comprises indium (In), copper (Cu), or aluminium (Al). ### Claim 9 (canceled) ### Claim 10 (canceled) ### Claim 11 (depends on 14) An ion source as claimed in claim 14, wherein the tarnishable or oxidisable metal or alloy comprising a tarnishable or oxidisable metal comprises germanium (Ge), antimony (Sb), zinc (Zn), cadmium (Cd), magnesium (Mg), silver (Ag), titanium (Ti), tantalum (Ta) or tungsten (W). ### Claim 12 (depends on 1) An ion source as claimed in claim 1, wherein the impact surface or target electrode comprises a metal other than a non-corrosive metal or alloy such as stainless steel. ### Claim 13 (depends on 1) An ion source as claimed in claim 1, wherein the impact surface or target electrode is arranged downstream of the nebuliser or electrospray probe and wherein, in use, a stream of uncharged droplets or charged droplets is directed so as to impact upon the impact surface or target electrode so as to form a plurality of analyte ions or secondary ions. ### Claim 14 (depends on 1) An ion source as claimed in claim 1, wherein the impact surface or target electrode is maintained either at: (i) ground or 0V; (ii) a positive potential; or (iii) a negative potential. ### Claim 15 (depends on 1) An ion source as claimed in claim 1, further comprising a device for adding helium gas to a nebuliser gas which is emitted, in use, by the nebuliser or electrospray probe and/or for otherwise supplying helium gas in the vicinity of the impact surface or target electrode. ### Claim 16 (depends on 1) An ion source as claimed in claim 1, wherein the impact surface or target electrode comprises one or more spike features or projections in order to enhance an electric field in the vicinity of the impact surface or target electrode. ### Claim 17 A Central Wire Electrospray ionisation (“CWESI”) ion source comprising: a nebuliser or electrospray probe for nebulising a sample, wherein the nebuliser or electrospray probe further comprises a central wire, wherein the central wire comprises a tarnishable or oxidisable metal or an alloy comprising a tarnishable or oxidisable metal. ### Claim 18 (depends on 1) A mass spectrometer comprising an ion source as claimed in claim 1. ### Claim 19 (depends on 18) A mass spectrometer as claimed in claim 18, wherein the mass spectrometer comprises an atmospheric pressure interface and wherein the ion source is arranged upstream of the atmospheric pressure interface. ### Claim 20 A method of ionising a sample comprising: nebulising a sample; and directing the nebulised sample on to an impact surface or target electrode, wherein the impact surface or target electrode comprises a tarnishable or oxidisable metal or an alloy comprising a tarnishable or oxidisable metal. ### Claim 21 (depends on 20) A method as claimed in claim 20, wherein the tarnishable or oxidisable metal comprises either gallium (Ga), indium (In), tin (Sn), lead (Pb), bismuth (Bi), copper (Cu), aluminium (Al), germanium (Ge), antimony (Sb), zinc (Zn), cadmium (Cd), magnesium (Mg), silver (Ag), titanium (Ti), tantalum (Ta) or tungsten (W). ### Claim 22 (canceled) ### Claim 23 (canceled) ### Claim 24 (canceled) ### Claim 25 (canceled) ### Claim 26 (depends on 20) A method of mass spectrometry comprising a method as claimed in claim 20.