How to Do Pipette Calibration

The pipette, which creates a vacuum to draw liquid, is a common instrument in science labs and health care facilities. Since the pipette is used to measure and transfer materials in a numbers-focused environment, the accuracy of the pipette's measurements is crucial. For this reason, pipette calibration should be performed in the lab or classroom every few months. Follow these simple steps for pipette calibration.

Things You'll Need

• Pipette
• Beaker
• Erlenmeyer flask
• Thermometer
• Weight balance
• Pipette filler
• Pen and paper

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Instructions

Procedure

• 1

  Clean and dry the pipette and beaker. This will remove any residue from past use that could skew measurements.

• 2

  Place distilled water in an Erlenmeyer flask and let it stand for about 15 minutes. After 15 minutes, measure the water's temperature.

• 3

  Determine the mass of the beaker to the nearest tenth of a milligram. Use a balance for this step.

• 4

  Fill the pipette, using the pipette filler, with the water from the flask and deposit the water into the beaker. Weigh the beaker again and record the difference in weight from the earlier measurement. Repeat this step three more times.

Calculation

• 5

  Calculate the mean of the four pipette measurements.

• 6

  Add 1.06 mg per gram to the mean mass. This must be done to adjust for the buoyancy of air during the weighing. If you are using a digital scale, ignore this step.

• 7

  Determine the density of water at the temperature you measured before.
  Then find the mean volume of water discharged by the pipette using the formula: Volume = mass / density.

• 8

  Compare your measurements and calculations to other results in pipette calibration in order to determine the precision of your pipette.