Decoupled flow and pressure setpoints in an extraction instrument using compressible fluids

• US 5,322,626 A
• Filed: 02/05/1993
• Issued: 06/21/1994
• Est. Priority Date: 03/02/1990
• Status: Expired due to Fees

• Current Assignee: Agilent Technologies, Inc.
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Zerenner, Ernest H., Engel, Steven J., Frank, Lenore R., Wurm, Christopher M., Nickerson, Mark A., Dryden, Paul C.
• Primary Examiner(s): Therkorn, Ernest G.
• Application Number:
  US08/013,899
• Time in Patent Office: 501 Days
• Field of Search: 202/169, 202/170, 203/49, 95/19, 95/82, 95/86, 96/103, 210/634, 210/635, 210/656, 210/659, 210/198.2, 210/137, 210/143, 422/255, 422/256, 436/161
• US Class Current: 210/634
• CPC Class Codes: B01D 11/0203 with a supercritical fluid
• CPC Class Codes: B01D 15/40 using supercritical fluid as mobile phase or eluent
• CPC Class Codes: G01N 2030/324 speed, flow rate
• 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: G01N 30/32 of pressure or speed G01N30/36 takes precedence

Abstract

Methods and apparatus for extracting sample components from complex matrices using supercritical fluid as the principal extracting solvent are disclosed. The invention takes advantage of the fact that the solvent power of a supercritical fluid is stepwise settable by the parameters of density, modifier concentration, and temperature. Accordingly, methods and apparatus for extracting a component from a sample using fluid flow system having a variable and controllable flow restriction are disclosed. The methods of the present invention comprise the steps of inserting the sample into the sample container section, inputting temperature, pressure, flow rate and extraction time set points. Flow rate is controlled and system pressure regulated by the variable flow restriction. The output stream from the extraction is then expanded through a nozzle and into a trap. In certain embodiments, the trap is filled with chemically active packing material. In other embodiments, a fractionation zone and other analytical instruments are coupled to the apparatus of the present invention. Methods and apparatus for rinsing the extraction instrument and for diluting the extraction fluid are also disclosed. Methods for operating a supercritical fluid extraction systems comprising a pressure and thermal control systems which are programmable to regulate the system to maintain such values within the design specifications during the extraction process.

Claims

1. A method of extracting a component from a sample using fluid flow system apparatus comprising control apparatus, at least one element having a variable and controllable flow restriction and a sample container section, comprising the steps of:

inserting the sample into the sample container section;

inputting temperature, pressure, flow rate and extraction time setpoints into control apparatus;

providing pressurized fluid;

directing the fluid to a pump which injects the fluid into the flow system apparatus as a supercritical fluid at the input flow rate setpoint;

sensing system pressure as fluid is pumped into the system;

controlling the variable flow restriction to achieve and to maintain the setpoint pressure and achieve a degree of decoupling of flow and pressure;

directing fluid through the sample at the setpoint flow rate; and

directing fluid mixture leaving the sample container section to an expansion nozzle section and flowing extraction fluid into a trap.

2. The method of claim 1, wherein the step of directing a fluid mixture through an expansion nozzle section comprises flowing the extraction fluid directly into a trap.

3. The method of claim 2, further comprising the step of sampling the fluid solution leaving sample container section prior to the step of directing the extraction fluid into the trap.

4. The method of claim 1, wherein the step of controlling the variable flow restriction comprises selecting a predetermined orifice opening size and adjusting the flow restriction to the predetermined opening size.

5. The method of claim 4, wherein the step of controlling said variable flow restriction comprises opening and closing a variable orifice.

6. The method of claim 1 further comprising the steps of rinsing the expansion nozzle by connecting a source of rinse solvent to the expansion nozzle section;

and connecting the expansion nozzle section tot he fluid flow system apparatus, whereby the rinse solvent supply is isolated from the expansion nozzle section.

7. The method of claim 1, further comprising the step of directing the extraction fluid through a fractionation bed means for retaining chemically active packing material.