Pipette by Numbers
Introduction
Materials
- Dyed water of various colors
- 96 well plate
- P20 Micropipette
- P200 Micropipette
- Tips
Procedure
How to use a micropipette
- Micropipettes are precise instruments used to accurately measure very small quantities of liquids in science laboratories. Image 1 shows a micropipette and the main components of the instrument. They are available in a variety of sizes to best match your measurement needs. The size of the micropipette is indicated directly on the instrument. The most commonly used micropipettes are the P10, P20, P200, and P1000. The number following the “P” refers to the maximum volume in microliters (µl) that can be measured using the instrument.
- Reading the volume on the micropipette:
P20 Micropipettes: The volume indicator consists of three number dials and is read from top to bottom. Black digits indicate tens of microliters and microliters; red digits indicate tenths of microliters. A P20 is used to measure volumes up to 20µL. NOTE: Do not dial past 20µL.
P200 Micropipettes: The volume indicator consists of three number dials and is read from top to bottom. Black digits indicate hundreds and tens of microliters; red digits indicate microliters. A P200 is used to measure volumes between 20µl and 200µL. NOTE: Do not dial past 200µL.
- Hold micropipette in one hand.
- Press disposable tips firmly onto the shaft to ensure an airtight seal. Do this by tapping the micropipette in the tip (tapping the tip on).
Do not use the micropipette without a disposable tip in place. Moisture can damage the piston and reduce accuracy.
- Depress plunger to the first stop. Holding the micropipette vertically, immerse the tip approximately two mm into the sample liquid. Allow the pushbutton to return slowly to the up position! (remember the glycerol from earlier?)
Do not lay a liquid loaded micropipette down. Moisture can run back inside causing damage to the micropipette
- Withdraw the tip from the liquid. Touch the tip end against the side wall of the receiving vessel and depress the plunger slowly to the first stop.
- Wait one second then press the plunger to the second stop, expelling any residual liquid in the tip.
- With the plunger fully depressed, withdraw micropipette and allow the plunger to slowly return to the up position.
- Discard the tip by depressing the ejector button. Use a fresh tip for the next sample to avoid contamination.
Pipette by Numbers
- Following the template on your team Benchling entry, pipette each volume and color into the correct wells.
- Calculate how much volume you should have added to your well plate based on the instructions.
- Measure how accurate your pipetting was by taking your plate to the scale and weighing how much heavier it is than a blank plate (1mL of water = 1000µL water = 1g)
- Let's see which group is the most accurate!
You will learn and practice the proper technique for measuring small volumes of liquid using a micropipette. Then you'll follow a micro-pipetting protocol to create an image by pipetting the proper color and volume of water into a well plate.