# US 10,309,941 B2 · Gas inlet system for isotope ratio analyzer and method of determining an isotope ratio > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,309,941 B2 - Document ID: US10309941B2 - Status: Granted - Kind: B2 - Application number: 15/684,762 - Filed: 2017-08-23 - Published: 2017-12-28 - Granted: 2019-06-04 - Earliest claimed: 2013-04-15 - Assignees: Thermo Fisher Scientific (Bremen) GmbH - Applicants: Thermo Fisher Scientific (Bremen) GmbH - Inventors: Eric Wapelhorst; Hans-Jürgen Schlüter; Oliver Kracht; Johannes Schwieters; Michael Krummen - Web page: https://patentgrep.com/patent/US10309941B2 ## CPC - G01N 33/0011: {Sample conditioning (preparing specimens for investigation G01N1/28)} - G01N 21/31: Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry {(G01N21/72 takes precedence)} - H01J 49/0422: {for gaseous samples (interfaces to gas chromatographs G01N30/7206)} - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract A gas inlet system for introducing gas into an isotope ratio analyzer, the gas inlet system including a reference system comprising: a first supply of a reference gas having a first known isotope ratio; a supply of a carrier gas, wherein the supplies of reference gas and carrier gas are each connected by respective reference and carrier gas lines to a first mixing junction where the reference gas and carrier gas combine; a mixing zone connected downstream of the first mixing junction wherein the combined reference gas and carrier gas mix together; an exit line for transporting the mixed gas from the mixing zone to the isotope ratio analyzer; and an opening on the exit line, wherein the opening is downstream of the mixing zone. Also provided is a method of determining an isotope ratio. ## Claims ### Claim 1 A gas inlet system for introducing gas into an isotope ratio analyzer, the gas inlet system including a reference system comprising: a first supply of a reference gas having a first known isotope ratio; a supply of a carrier gas, wherein the supplies of reference gas and carrier gas are each connected by respective reference and carrier gas lines to a first mixing junction where the reference gas and carrier gas combine; a mixing zone connected downstream of the first mixing junction wherein the combined reference gas and carrier gas mix together; an exit line for transporting the mixed gas from the mixing zone to the isotope ratio analyzer; a second mixing junction on the exit line from the mixing zone for mixing further carrier gas with the already mixed gas, the further carrier gas being supplied to the second mixing zone via a second carrier gas line; and an opening on the exit line, wherein the opening is downstream of the mixing zone. ### Claim 2 (depends on 1) A gas inlet system according to claim 1, the reference system further comprising a second supply of a reference gas having a second known isotope ratio, wherein the first and second supplies of reference gas may be each independently connected to the first mixing junction for mixing with the carrier gas. ### Claim 3 (depends on 1) A gas inlet system according to claim 1 wherein the reference gas is a substantially pure gas and the carrier gas is substantially free from the reference gas. ### Claim 4 (depends on 3) A gas inlet system according to claim 3 wherein the reference gas is CO2 and the carrier gas is CO2-free air or CO2-free nitrogen. ### Claim 5 (depends on 1) A gas inlet system according to claim 1 wherein the carrier gas flow to the first mixing junction is dynamically controllable by flow control means. ### Claim 6 (depends on 5) A gas inlet system according to claim 5 wherein the flow control means comprises a mass flow controller or proportional valve. ### Claim 7 (depends on 5) A gas inlet system according to claim 5 wherein the flow control means comprises at least one automatic or manual pressure regulator combined with at least one flow restriction downstream of the pressure regulator. ### Claim 8 (depends on 1) A gas inlet system according to claim 1 wherein the opening is in the form of an open capillary that is at least 0.5 mm in internal diameter and at least 5 mm in length. ### Claim 9 (depends on 8) A gas inlet system according to claim 8 wherein the flow rate through the open capillary is at least 0.5 ml/min. ### Claim 10 (depends on 1) A gas inlet system according to claim 1 wherein the mixing zone is at least 75 mm in length and at least 0.8 mm internal diameter. ### Claim 11 (depends on 1) A gas inlet system according to claim 1 wherein the mixing zone includes one or more bends and/or includes an angle along its length. ### Claim 12 (depends on 1) A gas inlet system according to claim 1 wherein the second mixing junction is downstream of the opening on the exit line. ### Claim 13 (depends on 1) A gas inlet system according to claim 1 wherein the carrier gas supplied to the second mixing junction is from the same supply of carrier gas that supplies the first mixing junction. ### Claim 14 (depends on 1) A gas inlet system according to claim 1 wherein the carrier gas supplied to the second mixing junction is not dynamically controllable. ### Claim 15 (depends on 1) A gas inlet system according to claim 1 wherein the exit line from the mixing zone has a flow restriction upstream of the second mixing junction but situated downstream of the opening junction and the second carrier gas line also has a flow restriction upstream of the second mixing junction. ### Claim 16 (depends on 1) A gas inlet system according to claim 1 wherein the mixed gas that enters the analyzer comprises a CO2 in air or CO2 in nitrogen concentration in the range between about 200-1500 ppm. ### Claim 17 (depends on 1) A gas inlet system according to claim 1 wherein each mixing junction is a T-junction. ### Claim 18 (depends on 1) A gas inlet system according to claim 1 wherein the opening on the exit line is provided at a junction that is a T-junction. ### Claim 19 (depends on 1) A gas inlet system according to claim 1 wherein one or more portions of the gas lines are provided in a machined block. ### Claim 20 (depends on 1) A gas inlet system according to claim 1 wherein the isotope ratio analyzer is an isotope ratio mass spectrometer or an isotope ratio optical spectrometer. ### Claim 21 (depends on 1) A gas inlet system according to claim 1 wherein the isotope ratio analyzer is for determination of a concentration dependence of an isotope ratio measurement and/or determination of an isotope ratio dependence of the isotope ratio measurement.