# US 2018/0321198 A1 · Pressure noise filter for chromatographic systems > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2018/0321198 A1 - Document ID: US20180321198A1 - Status: Published application - Kind: A1 - Application number: 15/967,752 - Filed: 2018-05-01 - Published: 2018-11-08 - Earliest claimed: 2017-05-01 - Assignees: Waters Technologies Corporation - Applicants: Waters Technologies Corporation - Inventors: Abhijit Tarafder; Michael O. Fogwill; Joshua A. Shreve; Joseph D. Michienzi; Steven J. Ciavarini - Web page: https://patentgrep.com/patent/US20180321198A1 ## CPC - G01N 30/28: Control of physical parameters of the fluid carrier - B01D 15/10: characterised by constructional or operational features - G01N 30/32: of pressure or speed (G01N30/36 takes precedence) - B01D 15/16: relating to the conditioning of the fluid carrier - B01D 15/40: using supercritical fluid as mobile phase or eluent - 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) - 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) ## Abstract The present disclosure relates generally to a system and a method for improving performance of a chromatography system using a highly-compressible fluid based mobile phase (e.g., CO2). In particular, the present disclosure relates to a system that uses a conduit, such as a convergent-divergent nozzle, for reducing pressure noise in a chromatography system using a highly-compressible fluid based mobile phase. The chromatography system can include a conduit, such as a convergent-divergent nozzle, disposed downstream of the column to reduce or prevent the propagation of pressure or density pulses from a back pressure regulator. ## Claims ### Claim 1 A composition for reducing pressure noise in a chromatography system comprising: a conduit having: a front opening with a first cross-sectional area, a back opening with a second cross-sectional area, and a throat section with a third cross-sectional area located between the front and back opening, wherein the third cross-sectional area is less than about 90% of both individual values of the first and second cross-sectional areas; and a heat exchanger in thermal communication with the conduit. ### Claim 2 (depends on 1) The composition of claim 1 wherein the cross-sectional area of the front opening, back opening, and the throat opening section are substantially circular. ### Claim 3 (depends on 1) The composition of claim 1 wherein the throat section is located closer to the front opening than to the back opening. ### Claim 4 (depends on 1) The composition of claim 1 wherein the throat section is located closer to the back opening than to the front opening. ### Claim 5 (depends on 1) The composition of claim 1 wherein the conduit comprises plastic, metal or a combination thereof. ### Claim 6 (depends on 1) The composition of claim 1 wherein the conduit comprises a plurality of overlaying panels which form the conduit, the conduit having an external surface and an internal surface; the composition further comprises one or more shutters attached to the external surface of the plurality of overlaying panels configured to adjust the size of the front opening, back opening, throat section, or combinations thereof; and a feedback loop to adjust a size of the one or more shutters. ### Claim 7 (canceled) ### Claim 8 (depends on 1) The composition of claim 1 wherein the conduit has a relatively constant pitch between the front opening and the throat section and between the back opening and the throat section. ### Claim 9 A chromatography system comprising: a pump for pumping a flow stream comprising a highly-compressible fluid based mobile phase; a column disposed downstream of the pump; a detector disposed downstream of the column; a convergent-divergent nozzle disposed downstream of the column; and a back pressure regulator downstream of the nozzle. ### Claim 10 (depends on 9) The system of claim 9 wherein the highly-compressible fluid comprises carbon dioxide. ### Claim 11 (canceled) ### Claim 12 (depends on 9) The system of claim 9 wherein the nozzle has a front opening having a first cross-sectional area, a back opening having a second cross-sectional area, and a throat section having a third cross-sectional area located between the first and second openings, the third cross-sectional area being less than about 90% of both individual values of the first and second cross-sectional areas. ### Claim 13 (depends on 9) The system of claim 9 wherein the back pressure regulator has a moveable valve shaft. ### Claim 14 (depends on 9) The system of claim 9 further comprising a pressure transducer probe connected to the nozzle configured to measure the pressure of the mobile phase in the throat section, and a heat exchanger connected to or in close proximity of the nozzle configured to heat the highly-compressible fluid based mobile phase flowing through the nozzle. ### Claim 15 (depends on 14) The system of claim 14 further comprising a feedback controller connected to the detector and the heat exchanger, wherein the controller is configured to determine the pressure noise in the detector and adjusting the heat exchanger to minimize the pressure noise. ### Claim 16 (depends on 9) The system of claim 9 wherein the nozzle has two or more channels wherein each channel has a throat section having a different cross-sectional area. ### Claim 17 (depends on 12) The system of claim 12 wherein at least the first, second or third cross-sectional area can be adjustable. ### Claim 18 (canceled) ### Claim 19 A method of improving the performance of a chromatography system comprising the steps of: filtering pressure noise in a CO2-based mobile phase flowing through the system utilizing a convergent-divergent nozzle positioned between a detector and a back pressure regulator in the system. ### Claim 20 (depends on 19) The method of claim 19 wherein the improved performance comprises decreasing baseline noise in a detector in the chromatography system. ### Claim 21 (depends on 19) The method of claim 19 wherein filtering comprises reducing the propagation of one or more pressure pulses from a back pressure regulator in the chromatography system. ### Claim 22 (depends on 19) The method of claim 19 wherein filtering comprises reducing the propagation of one or more density pulses from a back pressure regulator in the chromatography system. ### Claim 23 (depends on 19) The method of claim 19 wherein filtering comprises obtaining choked flow in the CO2-based mobile phase flowing through the system. ### Claim at position 24 -25. (canceled)