Method of and apparatus for dispensing liquid
First Claim
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1. A liquid pipetting system for aspirating and precisely dispensing small samples of a first liquid, having an outer conduit having outlet and supply ends;
- means connected to the supply end of the outer conduit for supplying a liquid thereto;
an inner conduit having inlet and supply ends and coaxially disposed in the outer conduit to define an annular space therebetween;
a sample pump means connected to the supply end of the inner conduit;
means for immersing the inlet end of the inner conduit in the first liquid; and
means for selectively actuating the sample pump means to aspirate the first liquid into the inlet end of the inner conduit;
the system characterized by a diluent pump connected to the supply end of the outer conduit for supplying a diluent liquid miscible with the first liquid thereto, and means for dispensing a portion of the aspirated first liquid by selectively activating the pumps to dispense a portion of the first liquid from the inner conduit into the diluent liquid in the annular space and simultaneously to flush the inlet end of the inner conduit with the diluent liquid.
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Abstract
A liquid pipetting system for aspirating and dispensing small samples of fluid and diluents. The pipetting system consists of a coaxial needle serving as the pipette tip and a metering system to control the fluids. Precise dispensing of small amounts of liquid from the inner needle is made possible by surrounding the sample liquid with a miscible diluting liquid thereby establishing a controlled interface and conveying the sample liquid into the receiving chamber with that miscible diluting liquid.
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Citations
12 Claims
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1. A liquid pipetting system for aspirating and precisely dispensing small samples of a first liquid, having an outer conduit having outlet and supply ends;
- means connected to the supply end of the outer conduit for supplying a liquid thereto;
an inner conduit having inlet and supply ends and coaxially disposed in the outer conduit to define an annular space therebetween;
a sample pump means connected to the supply end of the inner conduit;
means for immersing the inlet end of the inner conduit in the first liquid; and
means for selectively actuating the sample pump means to aspirate the first liquid into the inlet end of the inner conduit;
the system characterized by a diluent pump connected to the supply end of the outer conduit for supplying a diluent liquid miscible with the first liquid thereto, and means for dispensing a portion of the aspirated first liquid by selectively activating the pumps to dispense a portion of the first liquid from the inner conduit into the diluent liquid in the annular space and simultaneously to flush the inlet end of the inner conduit with the diluent liquid. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
- means connected to the supply end of the outer conduit for supplying a liquid thereto;
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9. A method for accurately aspirating and dispensing small samples of a first liquid using a probe having inner and outer coaxially disposed conduits defining a coaxial region comprising the steps of:
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aspirating the first liquid into the inner conduit; flushing the annular space between the conduits with a second liquid miscible with the first liquid to remove the first liquid from the entire exterior of the inner conduit and establish a controlled interface between the first and second liquids; dispensing a predetermined quantity of the first liquid from the inner conduit into the second liquid in the annular space; and flushing the annular space with a predetermined quantity of the second liquid thereby precisely dispensing the first liquid. - View Dependent Claims (10, 11, 12)
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Specification