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Solvent mixing in HPLC using low pressure solvent metering pumps

  • US 4,311,586 A
  • Filed: 04/22/1980
  • Issued: 01/19/1982
  • Est. Priority Date: 04/22/1980
  • Status: Expired due to Term
First Claim
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1. In a liquid chromatograph having solvent mixing apparatus producing a solvent mixture, a controller operative to regulate the total flow rate of the solvent mixture produced by the solvent mixing apparatus, a column, and a solvent mixture flow path defined between the solvent mixing apparatus and the column, the improvement comprising:

  • a sensing detector cell disposed in the solvent mixture flow path between the solvent mixing apparatus and the column;

    the cell having an inlet port for receiving an input flow of solvent mixture into the cell from the solvent mixing apparatus, an outlet port for withdrawal of an output flow of solvent mixture for introduction to the column, and a reservoir between the inlet and outlet ports for holding a volume of solvent mixture accumulated in an amount dependent upon the relative flow rates of the cell input flow and the cell output flow;

    the cell having first and second spaced-apart electrodes, one of the electrodes being provided to receive an applied electrical excitation and the other electrode being provided to sense the applied excitation through an accumulated volume of solvent mixture between the electrodes and produce an excitation response signal functionally related to the volume of the accumulated solvent mixture; and

    an electrical control circuit responsive to the sensing detector cell excitation response signal and coupled to the solvent mixture flow rate controller for effecting a reduction in the total flow rate of the produced solvent mixture when the volume of the accumulated solvent mixture in the cell exceeds a preset amount and for effecting an increase in the total flow rate of the produced solvent mixture when the volume of the solvent mixture accumulated in the cell becomes less than the preset amount.

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