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Take Care of Your Tools: How to Clean a Pipette

Like a Jedi’s light saber, your pipette is an extension of your arm and the lifeline to your (lab) existence. You probably should give it a little TLC once in a while to keep it free from contaminants.  Especially if you are doing experiments involving things like gene expression analysis.

Sure, you can use filter tips to help maintain a contaminant-free pipette. And you can always wipe the outside with 70% ethanol before each experiment.

But, what about giving your pipettes a deep cleaning?

No matter what the contaminant is, you have to start with taking your pipette apart.

Dismantling (scary but necessary)

  1. Dismantle your pipette – it should tell you how to do this in the instructions that came with it. If not, then for most types you need to remove the tip ejector, disconnect the upper and lower parts and remove the O-ring and the piston. (Just make sure you remember how to put it back together again!)
  2. Rinse the dismantled components in distilled water.

Removing specific contaminants

The next step depends on what contaminated your pipette, and the type of pipette you have.

You can refer to the manufacturer’s instructions for a detailed account of how to clean specific pipettes but here is a general overview on removing the most common contaminants:

Aqueous solutions, buffers or inorganic acids and alkalis

  1. Rinse all contaminated parts in 70% ethanol or 10% isopropyl alcohol
  2. Air dry at up to 60ºC

Organic solvents

  1. Allow the solvents to evaporate from the opened pipette on its own, or
  2. Alternatively, immerse the contaminated part in a detergent solution
  3. Air dry at up to 60ºC.

Radioactive substances

  1. Rinse the pipette with a strong detergent such as Decon® or Deconex®
  2. Rinse with distilled water several times
  3. Dry as described above
  4. Do a wipe test to make sure all radioactivity has been removed

Proteins

  1. Do NOT use alcohol to clean the pipette; it will set the proteins
  2. Rinse the contaminated parts with a detergent solution
  3. Rinse well in distilled water
  4. Air dry as above

Nucleic acids

  1. Boil the lower parts of the pipette in glycine/HCI buffer (pH 2) for 10 minutes
  2. Rinse with distilled water
  3. Air dry as above
  4. You can also use UV light to further reduce DNA contamination.

RNase

  1. Rinse with a detergent solution
  2. Rinse well with distilled water
  3. Rinse in 95% ethanol
  4. Allow to dry
  5. Soak the parts in 3% hydrogen peroxide for 10 minutes
  6. Thoroughly rinse with distilled water
  7. Air dry as above

A note about autoclaving:  Believe it or not, some pipettes can even be autoclaved (20 minutes at 121ºC) to remove infectious liquids or DNase.  Make sure you check the manufacturer’s instructions before shoving them in the autoclave though, or you might just find that your pipette has changed a little since you saw it last!

Assembly

Make sure all parts of your pipettes are completely dry before putting it back together.  Lightly lubricate the piston with silicone grease (usually provided with your pipette) and reassemble the pipette. And don’t forget the O-ring!  Check the calibration of your pipette before using it again.

Happy pipetting!

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