| 摘要 |
<p>A method of aspirating a liquid, includes: providing an aspirating probe which comprises a probe tip and a piston pump, wherein the probe tip and piston pump are in fluid communication; measuring an initial gas pressure in the tip of the aspirating probe prior to the liquid entering the liquid to be aspirated; moving the tip into the liquid, whereby a volume of gas is located between the top of the liquid and the piston of the piston pump; moving the piston of the piston pump a predetermined distance which corresponds to a selected volume of liquid to be aspirated; measuring the gas pressure in the volume of gas when the piston stops moving and the column of liquid pulled into the tip has equilibrated; determining the piston volume created by the movement of the piston; and determining the volume of liquid aspirated by the following formula: V liquid aspirated = V piston volume - ((P initial - P final) * Volume/unit pressure), wherein P initial is initial gas pressure before the liquid enters the tip, P final is final pressure of the volume of gas after the column of liquid has equilibrated, and Volume/unit pressure is the change of the gas volume for each change of unit pressure. In a preferred embodiment, the pressure is expressed in analog/digital counts. In another preferred embodiment, the liquid is a sample or reagent in a diagnostic analyzer.</p> |
