# US 8,465,982 B2 · Ion chromatography systems with flow-delay eluent recycle > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,465,982 B2 - Document ID: US8465982B2 - Status: Granted - Kind: B2 - Application number: 13/075,009 - Filed: 2011-03-29 - Published: 2011-07-21 - Granted: 2013-06-18 - Earliest claimed: 2008-02-22 - Assignees: Dionex Corporation - Applicants: Yan Liu; Kannan Srinivasan; Christopher A. Pohl; Sheetal Bhardwaj; Zhongqing Lu - Inventors: Yan Liu; Kannan Srinivasan; Christopher A. Pohl; Sheetal Bhardwaj; Zhongqing Lu - Web page: https://patentgrep.com/patent/US8465982B2 ## CPC - B01D 15/10: characterised by constructional or operational features - G01N 30/26: Conditioning of the fluid carrier; Flow patterns - G01N 30/96: using ion-exchange (G01N30/02, G01N30/90 take precedence) - G01N 2030/965: {suppressor columns} - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - 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) ## Abstract A chromatographic method including chromatographically separating sample ionic species in an eluent stream, detecting the separated sample ionic species, catalytically combining hydrogen and oxygen gases or catalytically decomposing hydrogen peroxide in a catalytic gas elimination chamber, and recycling the effluent stream from the chamber to the chromatography separation column. The residence time between the detector and the chamber is at least about one minute. Also, flowing the recycle sequentially through two detector effluent flow channels of an electrolytic membrane suppressor. Also, applying heat or UV energy between the detector and the chamber. Also, detecting bubbles after the chamber. Also, a Platinum group metal catalyst and ion exchange medium in the chamber. Apparatus for performing the methods. ## Claims ### Claim 1 A chromatographic method comprising the steps of: (a) injecting sample ionic species into an aqueous eluent stream from an eluent source, (b) chromatographically separating said sample ionic species in said eluent stream by flowing the same through chromatographic separation medium to exit as a chromatography effluent, (c) flowing said chromatography effluent through a detector to detect said separated sample ionic species in said chromatography effluent to exit as a detector effluent stream, flowing said detector effluent stream through a delay conduit downstream from said detector and upstream from a catalytic gas elimination chamber; (d) catalytically combining hydrogen and oxygen gases or catalytically decomposing hydrogen peroxide, or both, in said detector effluent stream by flowing it through said catalytic gas elimination chamber, to form water and reduce the gas content of the eluent effluent stream exiting said gas elimination chamber, and (e) recycling said catalytic gas elimination chamber effluent stream from said catalytic gas elimination chamber to said chromatography separation column, the residence time for flow of said detector effluent stream between said detector and said catalytic gas elimination chamber being at least about one minute to facilitate decomposition of unstable oxidative compounds. ### Claim 2 (depends on 1) The method of claim 1 in which said at least one minute residence time occurs in a delay chamber adjacent to said catalytic gas elimination chamber. ### Claim 3 (depends on 1) The method of claim 1 further comprising: (f) electrolytically forming said hydrogen and oxygen gases in said eluent stream. ### Claim 4 (depends on 1) The method of claim 1 further comprising flowing said catalytic gas elimination chamber effluent through an eluent purification column. ### Claim 5 (depends on 1) The method of claim 1 in which said delay conduit comprises a delay housing and said detector effluent stream flows through said delay housing in a tortuous path. ### Claim 6 (depends on 1) The method of claim 1 in which said delay conduit comprises a flow-through coil. ### Claim 7 (depends on 1) The method of claim 1 in which said delay conduit comprises a delay housing and a plurality of tubes, each tube being in parallel fluid communication with said gas elimination chamber effluent. ### Claim 8 (depends on 7) The method of claim 7 in which said delay conduit include a delay housing having a cross-sectional area transverse to fluid flow at least 3 times the cross-sectional area of said recycle conduit. ### Claim 9 A chromatographic method comprising: (a) injecting sample ionic species into an aqueous eluent stream from an eluent source, (b) chromatographically separating sample ionic species in an aqueous liquid eluent stream flowing through a chromatography separation medium, to form a chromatography effluent, (c) suppressing the chromatography effluent from step (b) by flowing it through a chromatography effluent flow channel in an electrolytic membrane suppressor to exit as a suppressor effluent stream, (d) flowing said suppressor effluent stream past a flow-through detector to exit as a detector effluent stream, (e) flowing the detector effluent stream from step (d) through a first detector effluent flow channel in said membrane suppressor on the opposite side of a first ion exchange membrane from said chromatography effluent flow channel, said detector effluent exiting said first detector effluent flow channel as a recycle stream, (f) flowing said recycle stream through a delay conduit, and then through a catalytic gas elimination chamber to catalytically combine hydrogen and oxygen gas, or catalytically decomposing hydrogen peroxide, or both, to form water thereby reducing the gas content in said recycle stream, and (g) flowing said recycle stream from said catalytic gas elimination chamber to said chromatography separation medium, the time for flow of said detector effluent from said first detector effluent flow channel to said catalytic gas elimination chamber being at least 0.5 minute to facilitate decomposition of unstable oxidation compounds. ### Claim 10 (depends on 9) The method of claim 9 further comprising, between steps (e) and (f), flowing said recycle stream from said first detector effluent flow channel through flow-through ion exchange medium in an electrolytic eluent generator separated from an eluent generator chamber by a charged generator barrier and applying a current across said generator ion exchange medium to electrolytically generate the same, electrolytically regenerating said suppressor ion exchange medium, and flowing said generated eluent to said chromatography separation medium. ### Claim 11 (depends on 1) The method of claim 1 further comprising: (f) detecting bubbles downstream of said catalytic gas elimination chamber; and (g) after the bubble detection, powering down a pump to stop the flow of said chromatographic effluent in step (c). ### Claim 12 (depends on 9) The method of claim 9 further comprising: (h) detecting bubbles downstream of said catalytic gas elimination chamber; and (i) after the bubble detection, powering down a pump to stop the flow of said suppressor effluent stream in step (d) and powering down the suppressor.