Apparatus and method for liquid chromatography
First Claim
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1. A method of rapidly bringing a chromatographic system to equilibrium pressure after start-up comprising the steps of:
- setting a pumping speed for pumping fluid from a pumping system into a chromatographic column at a predetermined rate of flow during a chromatographic run;
starting the chromatographic run, whereby the chromatographic system passes through an unstable period between start and reaching equilibrium pressure;
measuring, at a time of a low value of pressure near the time of start up, a characteristic of fluid being transferred from the pumping system to the chromatographic column related to the pressure of the fluid and establishing a range of said characteristic between two boundary conditions;
increasing the rate of flow from the pumping system to a multiple of the predetermined rate of flow starting with a first of said two boundary conditions; and
reducing said rate of flow from the pumping system to said predetermined rate of flow when said characteristic is between the first boundary condition and the last boundary condition at a point which is a reciprocal of said multiple of the distance between the first and the last boundary condition.
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Abstract
To stabilize flow rate in a single-stroke, syringe-type high pressure pump to a constant value after turn-on, a control system increases the pump speed until equilibrium conditions are reached and then pumps at the preset rate. The pumping system is operated at a flow rate ten times the preset flow rate. The control system senses the maximum rate of change of pressure, detects when the rate of change has dropped to nine-tenths of the maximum and, when the time derivative of the pressure has dropped to nine tenths of its maximum, the pump motor speed is reduced to the preset flow rate.
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Citations
45 Claims
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1. A method of rapidly bringing a chromatographic system to equilibrium pressure after start-up comprising the steps of:
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setting a pumping speed for pumping fluid from a pumping system into a chromatographic column at a predetermined rate of flow during a chromatographic run; starting the chromatographic run, whereby the chromatographic system passes through an unstable period between start and reaching equilibrium pressure; measuring, at a time of a low value of pressure near the time of start up, a characteristic of fluid being transferred from the pumping system to the chromatographic column related to the pressure of the fluid and establishing a range of said characteristic between two boundary conditions; increasing the rate of flow from the pumping system to a multiple of the predetermined rate of flow starting with a first of said two boundary conditions; and reducing said rate of flow from the pumping system to said predetermined rate of flow when said characteristic is between the first boundary condition and the last boundary condition at a point which is a reciprocal of said multiple of the distance between the first and the last boundary condition. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 25, 26)
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17. Apparatus for rapidly bringing a chromatographic system to equilibrium pressure after start-up comprising:
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pumping system means adapted to pump fluid through a chromatographic column; means for setting a pumping speed for pumping fluid from a pumping system means into said chromatographic column at a predetermined rate of flow; means for measuring, at a time of a low value of pressure of said fluid near the time of start-up, a characteristic of said fluid being transferred from the pumping system means to the chromatographic column related to the pressure of the fluid across a range of said characteristic between first and second boundary conditions; means for increasing the rate of flow of fluid from the pumping system means to a multiple of the predetermined rate of flow starting with said first boundary condition; and means for reducing said rate of flow from the pumping system means to said predetermined rate of flow when said characteristic is between the first boundary condition and the second boundary condition at a point which is a reciprocal of said multiple of the distance between the first and second boundary condition. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45)
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Specification