2. Accurate Pipetting:
A crucial part of liquid handling
Pipetting is the heart and soul of almost every experiment that involves liquid handling.
While manufacturers of Pipettes and Micropipettes ensure that their equipment delivers
reliable results, the real efficiency lies in the way we use it.
How we handle our equipment dictates its efficiency. Factors like technique, maintenance
and a better understanding of the inner components also play an essential role in
acquiring the skills required to Pipette Correctly.
3. Accurate Pipetting:
How do you do it?
Tip #1
Pre-wet the Pipette Tip
• Before aspirating any sample for delivery, aspirate and expel the sample liquid at least 3
times.
• A significant sample loss could be caused by evaporation within the tip but when you
pre-wet it, the humidity within the tip increases.
• This reduces any possible variation due to evaporation of the sample .
4. Accurate Pipetting:
How do you do it?
Tip #2
Never Place a Filled Pipette on its Side
• An air column separates the liquid in the pipette from the pipette barrel.
• If there’s any liquid left inside the pipette barrel, it may result in contamination and may
even cause serious damage due to corrosion.
5. Accurate Pipetting:
How do you do it?
Tip #3
Test Your Accuracy
• Dispense 100 µL onto a fine balance.
• The mass of the droplet you make should be around 0.1 g.
• Repeat this for 10 times and record the masses you obtain.
• If the variation is more than 0.5%, then you need to re-evaluate your pipetting technique
6. Accurate Pipetting:
How do you do it?
Tip #4
Take the Ambient Temperature into Account
• Your pipette is most likely calibrated at room temperature.
• There might be cases when you are working at a different temperature, and that may
result in your pipette not dispensing accurate volumes
7. Accurate Pipetting:
How do you do it?
Tip #5
Choose the Right Pipette for the Volume you Dispense
• The accuracy of your pipette decreases as the dispensed volume approaches the
minimum the pipette can handle.
• For example, if you are dispensing 15 µL, then a 1 mL pipette would be terrible, a 200 µL
pipette not so good, and 20 µL pipette ideal.
8. Accurate Pipetting:
How do you do it?
Tip #6
Check Your Pipettes Daily for Damage
• Every day, before starting your experiments, examine the nose of the pipette barrel you
would be working with, for damage.
• If there’s any, you should get it serviced as soon as possible since it won’t render
correct results.
Tip #7
Clean Your Pipette Before Use
Wash your pipette daily with 70% ethanol.
9. Accurate Pipetting:
How do you do it?
Tip #8
Store Your Pipette in a Pipette Holder
When you store your pipette vertically, it prevents any liquid in the pipette barrel to go further,
thereby avoiding corrosion.
Tip #9
Use Consistent Plunger Pressure and Speed
While aspirating and dispensing any sample, try to apply the same pressure and speed on the
plunger.
10. Accurate Pipetting:
How do you do it?
Tip #10
Examine the Tip Before Dispensing a Sample
Carefully remove any droplets outside the pipette with a lint free cloth, while making sure it
stays clear of the tip opening. This should be done every time before dispensing.