What is the purpose of using pipettes?

Pipettes are an essential laboratory tool used to dispense measured volumes of liquids. Pipettes most commonly work by creating a partial vacuum above the chamber that holds the liquid and selectively releasing this vacuum to draw up and dispense according to the preferred volume.

Why is it important to use a volumetric pipette in titration?

Volumetric flask is used to dilute original sample to known volume, so it is paramount that it contains exact volume. Pipette is used to transfer the solution, so it is important that it delivers known volume.

Why is a pipette not used in titration?

Pipettes are actually calibrated to retain a very small amount of solution in the tip when emptied, so although it’s tempting to force this out by blowing down the pipette or by squeezing the pipette filler, this is actually detrimental to the results gained from the titration.

What is the advantage of using displacement pipettes in experiments in cell and molecular biology?

Positive displacement pipettes offer reduced volatile solvent evaporation and prevent cross contamination, since there’s no contact between liquid and pipette.

How do electronic pipettes work?

Halfway between mechanical (manual) and robotic liquids handling, an electronic pipet makes pipetting faster and more reliable, with a much lower error rate than mechanical pipetting. The setting of the volume is electronic, and you push the button, and the plunger moves up and down electronically as well.

Why is a pipette used instead of a measuring cylinder?

Why use a pipette instead of a measuring cylinder? Unlike a measuring cylinder, a pipette will be more accurate with all of the sample, accounting for every drop of the substance being held within the tool.

Why are pipettes more accurate than burette?

Burettes have a stopcock at the bottom while a pipette has a dropper like system that releases liquid in the desired amount by lessening the vacuum. As another important difference between burette and pipette, pipettes are more accurate in releasing liquid in smaller quantities than burettes.

Why was it important to use a volumetric pipette and volumetric flasks?

A volumetric flask is used when it is necessary to know both precisely and accurately the volume of the solution that is being prepared. Like volumetric pipets, volumetric flasks come in different sizes, depending on the volume of the solution being prepared.

Why use a pipette instead of a measuring cylinder?

What is the most accurate way to read in a titration?

A pH electrode should be calibrated each day (at least once) it is used to get the most accurate reading. A two-point method is typically sufficient, as long as the appropriate buffers are used.

What is the difference between air displacement and positive displacement pipettes?

Both pipette types have a piston that moves in a cylinder or capillary. In air displacement pipettes, a certain volume of air remains between the piston and the liquid. In positive displacement pipetting, the piston is in direct contact with the liquid.