Decoupled flow and pressure setpoints in an extraction instrument using compressible fluids
First Claim
1. Apparatus for the extraction of components from a sample comprising:
- a pump for pumping a supercritical fluid comprising a pump motor and a pump motor speed control;
means for regulating the pressure of the output of said pump to a setpoint pressure;
a flow system for connecting a flow of supercritical fluid from the pump to an extraction section for retaining a sample;
an expansion nozzle connected to the extraction section and having an orifice of a variable predetermined opening size thereby achieving a degree of decoupling flow and pressure; and
a static trap subassembly connected directly to the expansion nozzle,whereby the pressure drop across said nozzle permits the recovery of dissolved material precipitating from the expanding fluid.
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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 are also disclosed.
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Citations
18 Claims
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1. Apparatus for the extraction of components from a sample comprising:
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a pump for pumping a supercritical fluid comprising a pump motor and a pump motor speed control; means for regulating the pressure of the output of said pump to a setpoint pressure; a flow system for connecting a flow of supercritical fluid from the pump to an extraction section for retaining a sample; an expansion nozzle connected to the extraction section and having an orifice of a variable predetermined opening size thereby achieving a degree of decoupling flow and pressure; and a static trap subassembly connected directly to the expansion nozzle, whereby the pressure drop across said nozzle permits the recovery of dissolved material precipitating from the expanding fluid. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. Apparatus for the extraction of components from a sample comprising:
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one or more sources of extraction solvent fluid; one or more extraction solvent fluid input ports; a high pressure pump connected to the input ports; a pressure transducer to measure the pressure of the fluid delivered by the high pressure pump; an extraction chamber flow system connected to the high pressure pump comprising an extraction chamber for retaining the sample in the flow stream of the fluid and a sample input module for containing the sample in the extraction chamber; a bypass flow system connected to the high pressure pump which routes fluid flow around said extraction chamber section; means for merging the bypass flow system and extraction chamber flow system together to create a merged flow stream; sample collection means for separating the extracting solvent fluid from components extracted from said sample connected to the merged flow stream, comprising at least one variable expansion nozzle connected directly to a static trap subassembly; a flow transducer; and at least one sample collection vessel, whereby pressurized liquid flows through the sample under independently predetermined and controlled conditions of flow rate and pressure, and whereby the pressurized fluid dissolves one or more selected components from the sample, said components being collected by the sample collection vessel.
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Specification