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Reverse Pipetting
Reverse pipetting is a technique to dispense a measured quantity of liquid by means of air displacement pipette. The technique is mainly recommended for solutions with a high viscosity or a tendency to foam: as it reduces the risk of splashing, foam or bubble formation. Reverse pipetting is more precise in dispensing small volumes of liquids containing proteins and biological solutions compared to forward pipetting, which is mostly used for aqueous solutions, such as buffer solution, buffers, diluted acids or alkalis. How it works In reverse pipetting, the volume aspirated to the tip is bigger than the volume delivered to the receiving vessel. The excess of volume compensates for the liquid that remains as film inside the tip during dispensing. Liquid aspiration is achieved by creating vacuum by means of the vertical travel of a metal or ceramic piston within an airtight sleeve. As the piston moves upward, driven by the depression of the plunger, a vacuum is created in the sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Air Displacement Pipette
Piston-driven air displacement pipettes are a type of micropipette, which are tools to handle volumes of liquid in the microliter scale. They are more commonly used in biology and biochemistry, and less commonly in chemistry; the equipment is susceptible to damage from many organic solvents. Operation These pipettes operate by piston-driven air displacement. A vacuum is generated by the vertical travel of a metallic or ceramic piston within an airtight sleeve. The upward movement of the piston, driven by the depression of the plunger, creates a vacuum in the space left vacant by the piston. To fill the vacuum, air from the tip rises, which is then replaced by the liquid that is drawn up into the tip and thus available for transport and dispensing elsewhere. Sterile technique prevents liquid from coming into contact with the pipette itself. Instead, the liquid is drawn into and dispensed from a disposable pipette tip that is discarded after transferring fluid and a new pipette ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
