Matching thermally modulated variable restrictors to chromatography separation columns

Abstract

Thermally modulated variable restrictors used in chromatography systems enable independent control of system pressure and linear velocity of a compressible mobile phase passing through a chromatography column. A method for configuring a chromatography system with independent control of system pressure and mass flow rate of a compressible mobile phase includes determining a type of chromatography separation column to be used in the chromatography system, matching a thermally modulated variable restrictor to the type of chromatography separation column for use together during operation of the chromatography system, and bundling the chromatography column with its matching thermally modulated variable restrictor for distribution as a single package.

What is claimed is: 
     
         1 . A method for configuring a chromatography system with independent control of system pressure and mass flow rate of a compressible mobile phase, comprising:
 determining a type of chromatography separation column to be used in the chromatography system;   matching a thermally modulated variable restrictor to the type of chromatography separation column for use together during operation of the chromatography system; and   bundling the chromatography separation column with its matching thermally modulated variable restrictor for distribution together as a single unit.   
     
     
         2 . The method of  claim 1 , wherein the matching of a thermally modulated variable restrictor to the type of chromatography separation column is based on a mass flow rate of the compressible mobile phase through the chromatography separation column during operation of the chromatography system. 
     
     
         3 . The method of  claim 1 , wherein each different type of chromatographic separation column is bundled with a matching thermally modulated variable restrictor of a different temperature-pressure characteristic. 
     
     
         4 . The method of  claim 1 , wherein the matching of a thermally modulated variable restrictor to the type of chromatography separation column includes determining a temperature range over which to operate the thermally modulated variable restrictor in order to regulate system pressure. 
     
     
         5 . The method of  claim 1 , wherein the matching of a thermally modulated variable restrictor to the type of chromatographic separation column includes determining a length of the thermally modulated variable restrictor to be heated. 
     
     
         6 . The method of  claim 1 , wherein the matching of a thermally modulated variable restrictor to the type of chromatography separation column includes determining a size of an internal diameter of the thermally modulated variable restrictor. 
     
     
         7 . The method of  claim 1 , wherein the thermally modulated variable restrictor that is matched to the type of chromatography separation column achieves a constant linear velocity of mobile phase through the chromatography separation column during operation of the chromatography system. 
     
     
         8 . A kit for a chromatography system, comprising:
 a chromatography separation column to be used in the chromatography system; and   a thermally modulated variable restrictor matched to the type of chromatography separation column for use together during operation of the chromatography system.   
     
     
         9 . The kit of  claim 8 , wherein the matched thermally modulated variable restrictor comprises:
 a restrictor body having a fluidic channel with an inlet end that receives the compressible mobile phase from the chromatography separation column and an outlet end through which the mobile phase leaves the fluidic channel;   a restrictor tip disposed adjacent the restrictor body at the outlet end of the fluidic channel, the restrictor tip having an egress opening that is smaller than an internal diameter of the fluidic channel; and   a heating element thermally coupled to a subsection of the fluidic channel between the inlet and outlet ends to heat the compressible mobile phase passing through that subsection of the fluidic channel.   
     
     
         10 . The kit of  claim 9 , wherein the restrictor body comprises tubing to provide the fluidic channel, and wherein the heating element includes a wire coiled around the tubing. 
     
     
         11 . The kit of  claim 10 , wherein the restrictor body comprises a microfluidic substrate within which the fluidic channel is formed. 
     
     
         12 . The kit of  claim 11 , wherein the restrictor tip and restrictor body are integrally formed in the microfluidic substrate. 
     
     
         13 . The kit of  claim 11 , wherein the restrictor tip is nondestructively detachable from the restrictor body. 
     
     
         14 . The kit of  claim 9 , wherein the matched thermally modulated variable restrictor includes a fluidic connector for joining the restrictor body to the restrictor tip. 
     
     
         15 . The kit of  claim 9 , wherein the restrictor tip comprises a converging-diverging restrictor. 
     
     
         16 . The kit of  claim 9 , wherein the restrictor tip has a tapered region that tapers to the egress opening. 
     
     
         17 . The kit of  claim 9 , wherein the restrictor tip has a frit with the egress opening. 
     
     
         18 . The kit of  claim 9 , wherein the restrictor tip includes a straight section with an internal diameter that is smaller than the internal diameter of the fluidic channel. 
     
     
         19 . The kit of  claim 9 , wherein the restrictor tip is an integral restrictor. 
     
     
         20 . The kit of  claim 8 , wherein the chromatography separation column is a supercritical fluid chromatography (SFC) column.