pipetting
Pipetting with both accuracy and precision is very important for a biologist. It is also important to take car of the pipette.
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Always pipette vertically and do not let liquid into the pipettes
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Pipette slowly, especially if the liquid is viscous
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Set the pipette to its maximum volume when not in use.
The three videos below give you a nice introduction to pipetting:
Pipetting: Basic Pipetting
Micropipette technique demo
Four Common Pipetting Errors - Techniques Demonstration
Under a constant temperature and atmospheric pressure, the density of distilled water is constant. The volume of water can be determined by weighting dispensed water.
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Measure the water temperature and record it.
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Place a plastic cup or a Petri dish on the balance and adjust the weight to zero.
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Put a tip onto the pipette and set the volume which is to be tested.
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Dispense a set volume of water. It is a good idea to calibrate both with a small and large volume:
| Model | Small volume (µL) | Large volume (µL) |
|---|---|---|
| P20 | 2 | 10 |
| P200 | 20 | 100 |
| P1000 | 100 | 500 |
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Close the door of the balance and record the weight after it has stabilized.
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Repeat 10 times adjusting the balance to zero after each measurement.
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Use this form to record and calculate precision and accuracy
