Apparatus and method for supercritical fluid extraction

• US 5,268,103 A
• Filed: 03/05/1993
• Issued: 12/07/1993
• Est. Priority Date: 07/13/1990
• Status: Expired due to Term

• Current Assignee: Teledyne Isco, Inc. (Thermo Fisher Scientific Incorporated)
• Original Assignee: Isco, Inc. (Teledyne Technologies Incorporated)
• Inventors: Macomber, Robert J., Allington, Robert W., Jameson, Daniel G.
• Primary Examiner(s): Sever, Frank
• Application Number:
  US08/027,257
• Time in Patent Office: 277 Days
• Field of Search: 210/634, 210/541, 210/542, 203/16, 203/19, 422/256-260
• US Class Current: 210/634
• CPC Class Codes: B01D 11/0203 with a supercritical fluid
• CPC Class Codes: B01D 11/0407 the supercritical fluid acting as solvent for the solute
• CPC Class Codes: B01D 15/40 using supercritical fluid as mobile phase or eluent
• CPC Class Codes: F04B 15/08 the liquids having low boiling points
• CPC Class Codes: F04B 2205/03 Pressure in the compression chamber
• CPC Class Codes: F04B 2205/05 Pressure after the pump outlet
• CPC Class Codes: F04B 2205/09 Flow through the pump
• CPC Class Codes: F04B 49/065 and making use of computers
• CPC Class Codes: F04B 9/042 the means being cams
• CPC Class Codes: F05B 2230/41 Hardening; Annealing
• CPC Class Codes: F05C 2201/0493 Tin
• CPC Class Codes: F05C 2253/12 Coating
• CPC Class Codes: F16K 15/1823 for ball check valves
• CPC Class Codes: G01F 1/34 by measuring pressure or differential pressure
• CPC Class Codes: G01N 1/34 Purifying; Cleaning processes or apparatus for extracting or separating nucleic acids from biological samples C12N15/1003
• CPC Class Codes: G01N 1/40 Concentrating samples
• CPC Class Codes: G01N 2001/4033 sample concentrated on a cold spot, e.g. condensation or distillation
• CPC Class Codes: G01N 2001/4061 Solvent extraction
• CPC Class Codes: G01N 2030/6013 interfaces to detectors
• CPC Class Codes: G01N 2035/0441 for samples
• CPC Class Codes: G01N 30/02 : Column chromatography
• CPC Class Codes: G01N 30/28 : Control of physical parameters of the fluid carrier
• CPC Class Codes: G21F 5/015 : for storing radioactive sources, e.g. source carriers for irradiation units; Radioisotope containers

Abstract

To avoid deposits on the restrictor that channels extractant into a collector, a heated capillary tube pressure release restrictor, has a thermally insulated outlet end in a collecting trap substantially colder than the capillary tube. The restrictor is heated between the insulation and the capillary tube by Joulean heating. The solvent in the trap is at a pressure of 5 to 200 psi above atmospheric pressure. The thermal resistance of the insulation is selected to reduce the heat added to the extractant to a minimum and yet cause the temperature of the extractant to be in a range within which it is sufficiently hot so it does not freeze when added to the collection solvent but not so hot as to reduce partitioning of the extract and extractant before the extractant leaves the collection solvent. It has a thermal conductivity no greater than 60 BTU'"'"'s per hour, per square foot, per inch for a one degree Fahrenheit difference.

Claims

1. A supercritical fluid extractor comprising:

means for supercritical fluid extraction;

said means for supercritical fluid extraction including an outlet tube means;

a collector;

said collector including a capillary tube pressure release restrictor commumicating with said outlet tube means wherein fluid from said means for supercritical fluid extraction flows into said capillary tube pressure release restrictor;

said capillary tube pressure release restrictor having a collector tube outlet end located in a collecting trap colder than the said capillary tube; and

means for controlling the flow of heat between said fluid from said means for supercritical extraction and said collecting trap.

2. The apparatus of claim 1 wherein said means for controlling the flow of heat includes an electric heating element in proximity to fluid passing through the said capillary tube.

3. The apparatus of claim 1 wherein the means for controlling the flow of heat includes an electrical resistance sensor.

4. The apparatus of claim 1 wherein the means for controlling includes a heating means.

5. The apparatus of claim 4 wherein the heating means includes means for heating with an electrical current brought about by an alternating magnetic field.

6. The apparatus of claim 4 in which the means for heating is a means for applying an alternating magnetic field.

7. The apparatus of claim 4 in which the means for heating includes electromagnetic energy means.

8. The apparatus of claim 7 wherein the electromagnetic energy means includes means for heating with infrared radiation.

9. The apparatus of claim 1 wherein the means for heating includes at least one of conduction and convection from at least one of a heated liquid, solid or gas.

10. The apparatus of claim 1 wherein:

the capillary tube, pressure release restrictor comprises a thermally insulated, metal capillary tube restrictor for supercritical fluid extraction;

said thermally insulated metal capillary tube restrictor being directly electrically heated and including insulation, wherein the surface of the said insulation on the said tube restrictor forms a substantially coaxial cylindrical surface about the said tube restrictor.

11. The apparatus of claim 10 in which the said metal part of the capillary possesses a temperature coefficient of resistance which serves as the element which senses the temperature.

12. A supercritical fluid extraction system according to claim 1 incorporating means for off-line solvent collection of the extracts after all of the extractant has been collected.

13. A supercritical fluid extraction according to claim 1 wherein the means heating extends to the outlet end of capillary tube, pressure release restrictor.

14. A capillary tube, pressure release restrictor according to claim 1 wherein the said trap is a solvent trap pressurized to a pressure of 5 to 200 psi above atmospheric pressure.

27. A supercritical fluid extraction according to claim 1 wherein the means heating does not extend to the outlet end of capillary tube, pressure release restrictor.

15. A temperature control system for comprising:

means for cooperating with a supercritical fluid extractor including,

a directly heated, at least partially metal, capillary tube pressure release restrictor;

a closed loop temperature control system wherein the capillary acts as a heating element by longitudinal conduction of electric current through its metal part; and

an element which senses the temperature of the capillary tube to provide feedback to a feedback temperature control means;

said capillary tube having an outlet end and having thermal insulation in a region around and near the said outlet end, which insulation thermally insulated said region of the tube from a colder collecting trap which surrounds the said region.

16. An apparatus in accordance with claim 15 wherein the insulation is selected to reduce the heat added to the extractant to a minimum and yet cause the temperature of the extractant to be in a range within which it is sufficiently hot so it does not freeze or deposit within the capillary tube but not so hot as to reduce partitioning of the extract and extractant before the extractant leaves the collection solvent.

17. An apparatus in accordance with claim 16 wherein the insulation has a thermal conductivity no greater than 50 BTU'"'"'s per hour, per square foot, per inch for a 1 degree Fahrenheit difference and a thickness of at least 0.001 inches.

18. The apparatus of claim 15 further comprising:

a return path for the said current;

said return path being in the form of an outer metal tube surrounding the said capillary tube and sealingly connected to provide an electrical connection to the said outlet end of the said metal capillary tube;

said outer tube extending outside the collecting trap; and

the outer metal tube being thermally insulated from the said capillary, except at the location of the said connection.

19. An apparatus in accordance with claim 18 wherein the insulation is selected to reduce the heat added to the extractant to a minimum and yet cause the temperature of the extractant to be in a range within which it is sufficiently hot so it does not freeze or deposit within the capillary tube, but not so hot as to reduce partitioning of the extract and extractant before the extractant leaves the collection solvent.

20. An apparatus in accordance with claim 19 wherein the insulation has a thermal conductivity no greater than 50 BTU'"'"'s per hour, per square foot, per inch for a 1 degree Fahrenheit difference and a thickness of at least 0.001 inches.

21. A supercritical fluid extraction system according to claim 18 incorporating means for off-line solvent collection of the extracts.

22. A supercritical fluid extraction system according to claim 18 wherein the means heating does not extend to the outlet end of capillary tube, pressure release restrictor.

23. A supercritical fluid extraction system according to claim 18 wherein the means heating extends to the outlet end of capillary tube, pressure release restrictor.

24. A capillary tube, pressure release restrictor according to claim 18 wherein the said trap is a solvent trap pressurized to a pressure of 5 to 200 psi above atmospheric pressure.

25. The apparatus of claim 15 wherein the said trap is a solvent trap.

26. A supercritical fluid extraction system according to claim 15 incorporating means for off-line solvent collection of the extracts.

28. A supercritical fluid extraction according to claim 15 wherein the means heating does not extend to the outlet end of capillary tube, pressure release restrictor.

29. A supercritical fluid extraction according to claim 15 wherein the means heating extends to the outlet end of capillary tube, pressure release restrictor.

30. A capillary tube, pressure release restrictor according to claim 15 wherein the said trap is a solvent trap pressurized to a pressure of 5 to 200 psi above atmospheric pressure.