Typically, the density of water is 0.996 kg/dm3, for ethanol 0.79 kg/dm3 and for sulfuric acid (H2SO4) 1.85 kg/dm3. The density varies according to thetemperature and air pressure. If the temperature of the liquid, pipette and air is the same, the accuracy is not significantly affected.ĭensity is the mass/volume ratio of the liquid.
The figure below shows the change in volume when the liquid has a different temperature than the pipette and air. The most important factor in pipetting accuracy is the liquid temperature. To empty the tip completely the operating button is pressed to the second stop (blow out).įactors affecting the accuracy of Air Displacement Pipettes:
When the operating button is pressed to the first stop again, the air dispensesthe liquid. After immersing the tip into the liquid, the operating button is released.This creates a partial vacuum and the specified volume of liquid is aspiratedinto the tip. When the operating button is pressed to the first stop, the piston expels thesame volume of air as indicated on the volume setting. The piston moves to the appropriate position when the volume is set. How does an Air Displacement Pipette work? However, conditions such as temperature, atmospheric pressure as well as the specific gravity and viscosity of the solution may have an effect on the performance of air displacement pipettes. Air Displacement Pipette, used for standard pipetting applications, is highly accurate.
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