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Increase accuracy by pre-wetting your tip |
 Your pipette tip should be at the same temperature as the solution that you are pipetting, otherwise accuracy is compromised. The fastest way to equilibrate your pipette tip to the solution’s temperature is to prewet the tip – pipette the solution up and down the tip a few times before you actually use it for dispensing. |
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Have you found that some of your 'sterile' pipette tips are dirty? |
 Check inside your tip boxes for accumulated rubbish, under the tip rack itself! You'll be surprised at how much dirt you might find, which doesn't magically go away when the tip box is autoclaved. |
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Are you pipetting small volumes from your bottle or centrifuge tube? |
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Bottles and tubes provide a useful beaker for easy pipetting: the insides of their lids. Pour the contents of the tube into its lid and pipette from that - its much easier.
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Have you been pipetteing volatile liquids? |
 After pipetting volatile liquids (like β-mercaptoethano), some of the liquid will vaporise when it is in your pipette tip. This could enter the pipette itself when you release the pipette's dispensing button. So try to use a filter tip to stop this from happening. Otherwise, make sure you eject the tip from the pipette right after dispensing the liquid from it - don't release the button from the "second stop" or it could suck up the vaporised liquid into the pipette itself.
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Increase accuracy with viscous samples |
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When making mixtures of viscous liquids and water (e.g. 50% glycerol), make it up in larger volumes and the room for pipetting errors decreases. When pipetting viscous liquids use reverse pipetting techniques. For
larger volumes use a serological pipette and again, reverse pipette it
(e.g. to pipette 4 ml, suck up 5 ml and dispense, leaving 1 ml behind).
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Pipette viscous liquids easier |
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When pipetting viscous liquids, cut off a bit from the bottom of the pipette tip to allow for a larger flow of liquid in and out of the tip. Accuracy is compromised though! For really viscous liquids, cut at an angle to make the diameter of the tip end bigger. |
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Serological pipettes: how you stop the dribbling! |
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Prevent the 25-100 ml serological pipettes from dribbling: Apply a low suction pressure by pressing the top button softly, and the liquid won't dribble out as you move it around. (Be careful not to suck the liquid to the top though!) |
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Pre-wet your pipette to increase accuracy |
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Pre-wet your pipette tip by pipetting up and down with the sample first - this is especially important when pipetting alcohols so they don't evaporate in the tip. |
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