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Method and apparatus for determination of analyte concentration

  • US 5,954,954 A
  • Filed: 06/20/1997
  • Issued: 09/21/1999
  • Est. Priority Date: 10/16/1992
  • Status: Expired due to Fees
First Claim
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1. A restrictor for flow of supercritical solvent comprising:

  • a housing having a central chamber and a first port, second port and third port connected to the central chamber;

    a high pressure tube connected to the first port which delivers supercritical solvent to the chamber through the first port;

    an actuator mechanism connected to the second port;

    a needle connected to the actuator mechanism, said needle extending from the actuator mechanism through the chamber and through the third port, said actuator mechanism moving the needle to maintain a desired flow of supercritical solvent out the third port and compensating for flow rate error due to temperature effects, said needle having a needle end; and

    an outlet tube which is connected to the third port and extends from the third port, said outlet tube surrounding the needle, said outlet tube having an opening which conforms with the needle and to control the flow of solvent out the third port and the change in pressure of the solvent, said needle end and outlet tube opening remote from the housing.

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