Pipettes are one of the most commonly used equipment in a science laboratory. The pipetting accuracy and precision are very crucial to determine the exact results of an experiment and its success.
What is Pipetting?
Pipetting is the process of expelling the exact volume of liquid from the pipette tip repeatedly. An optimal pipetting technique requires careful handling and practice.
Here are some pipette tips to help you.
Before Use
- Clean your pipettes every day before use.
- Use tip that is well-fitted so that the air does not escape while drawing up and dispensing liquid.
- Learn to pipette by practising a few times before doing the actual experiment.
- Pre-wet the tip before the experiment. This is because when you dispense the liquid from a pipette, it leaves a layer of liquid on the tip, resulting in slightly lower dispensed volume. If you pre-wet the tip, this will not happen. In order to follow the pre-wet process, draw the liquid into the pipette and then dispense it back to the vessel from which it was taken. You will see the coating on the tip. Next time you repeat the action, the liquid coating will not be left.
During Use
- At the time of drawing up liquid, make sure you immerse the tip to the proper depth in just right proportion according to the volume of pipette. If you immerse too much, then samples can cling to the tip outside. If you immerse too less, it could lead to air aspiration.
- When you have drawn the liquid in a required measure, leave the tip of the pipette immersed for a second. This should be done for the liquid in the tip to stop moving after the aspiration action is over so that volume does not end up low.
- Every time you draw the liquid, remember to apply the same pressure and speed so that the results are consistent.
- When you pull out the pipette from the container, keep it straight and vertical and do not let it touch the sides of the vessel. If you do tilt it to an angle, it is likely to alter the volume of the sample. If it touches the vessel, it will become prone to surface tension and again lose its volume.
- Before dispensing, you may see some excess droplets outside the tip of the pipette. Absorb them carefully and gently with a lint-free cloth. After dispensing, adjust the position of the tip to touch the side of the vessel to let the residual sample leave the pipette.
After Use
- Store the pipettes vertically in a pipette holder.
- Check the pipettes daily for any damage and get them serviced regularly.
The above tips will help you reduce or rather eliminate errors in pipetting technique.
