Do you remember the first time that you used a pipette? It was probably sophomore year of college. If your class was like mine, there was not much time for training. We were focused on completing the lab assignment and recording data. Fast forward ten years, now pipetting is like a reflex. We just do it without thinking.
Today, I will provide some pipetting tips to help college level pipette users and new lab technician. First, there are two primary modes of pipetting – forward and reverse. Of the two manual pipetting modes, forward pipetting which requires that an exact volume be aspirated and transferred is probably the most common. I will explain this technique today. Reverse pipetting will be covered next week.
Step #1) It is always a good practice to pre-wet the tip prior to beginning a pipetting procedure. Just draw up the liquid into the tip and then disperse it back into the original vessel. This procedure should be performed 2-3 times. Once the volume is selected, depress the plunger button to the first stop and immerse the tip vertically a few millimeters into the liquid.
Step #2) Then smoothly and slowly release the plunger button, which will aspirate the liquid into the tip.
Step #3) Be sure to hold the pipette vertically when drawing up liquid.
Step #4) To dispense the liquid into the receiving vessel depress the plunger button to the first stop again, letting the tip touch the side wall of the container to take advantage of the elimination of surface tension through contact with the container which will ensure that the measured liquid being dispensed doesn’t remain in the tip.
Step #5)When dispensing, the pipette is held at a 45 degree angle. By depressing the plunger to the second stop, blow out expels any remaining liquid from the tip.
Lastly, the proper handling of a pipette when not in use is also important. After removing the used tips, pipettes are always stored in an upright position. A pipette should never be placed down on the lab bench. It should always be kept on a stand. These practices will ensure the pipette is contamination free. Do you have any other useful tips? Please post your tips in the comments below. Happy Pipetting!