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Apparatus and method for liquid chromatography

  • US 4,775,481 A
  • Filed: 08/10/1987
  • Issued: 10/04/1988
  • Est. Priority Date: 09/09/1981
  • Status: Expired due to Term
First Claim
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1. A method of rapidly bringing a chromatographic column through a transitory period from starting to equilibrium pressure comprising the steps of:

  • setting a pumping speed for pumping fluid from a pumping system into said column at a predetermined rate of flow;

    measuring the pressure of the fluid;

    measuring the rate of flow of the fluid;

    determining the difference between the equilibrium pressure and the measured pressure to obtain a pressure error;

    increasing the rate of flow from the pumping system under the control of at least a function of said pressure error and measured rate of flow until the equilibrium value of pressure is reached;

    reducing said rate of flow from the pumping system to said predetermined rate of flow;

    the step of increasing the rate of flow until said estimated equilibrium value of pressure is reached including the step of controlling the rate of flow with a feedback signal that causes the pumping speed to increase substantially proportionally to the change in the difference between the set pressure and the measured pressure substantially independently of the rate of flow wherein the feedback signal is formed from the pressure error and a function that increases at a decreasing rate as the rate of flow increases.

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