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Techniques Lab A: Manipulating Small Volumes
PART 1--Directions for Using Micropipets

Set pipet volume only within the range specified for that micropipet. Do not attempt to set a volume beyond the pipet's minimum or maximum values.
When using a micropipet, first apply a tip.Forgetting to do this would cause liquid to be sucked into the nose cone. Since a micropipet works by air displacement, its internal mechanism must remain dry.
Always keep a micropipet in a vertical position when there is fluid in the tip.Do not allow liquid to accidentally run back into the nose cone.
Use your thumb to control the speed at which the plunger rises after taking up or ejecting fluid. Releasing the plunger too abruptly will cause liquid to pop up into the nose cone and damage the piston.
Setting and Preparing the Micropipet
1. Check that you have the right micropipet. There may be three sizes in the lab -- a "P-20" (for 2 to 20 µL), a "P-200" (for 20-200 µL), and a "P-1000" (for 200-1000 µL).
2. Dial the desired volume. Do you understand how to read the scale? If not -- ASK!
3. Push the end of the pipet into the proper-size tip. The yellow tips are for P-20's and P-200's; the larger blue tips are for P-1000's.
How to Take Up Sample with a Micropipet
4. Before picking up the micropipet, open the cap or lid of the tube from which you are taking fluid (or, have your lab partner do this and hand the tube to you).
5. Hold the micropipet in one hand, almost vertical; hold the tube in your other hand. Both should be almost at eye-level.
NOTE: the person holding the micropipet is also the person who should be holding the tube!
6. Before lowering the tip into the liquid,push down the plunger to the first stop and hold in this position.(DO NOT GO PAST THE FIRST STOP OR YOU WILL GET AN INCORRECT VOLUME), then...
7.      ... dip the tip into the solution to be pipetted.
8. Draw fluid into the tip by slowly releasing the plunger. (Cap and put down the tube with the liquid or hand it to your partner.)
How to Expel a Sample From the Micropipet
9. With your other hand (or, have your lab partner do this), open the cap or lid of the tube into which you are ejecting the fluid.
10. Hold the micropipet in one hand, almost vertical; hold the tube in your other hand. Both should be about at eye-level.
11. Touch the micropipet tip to the inside wall of the reaction tube into which you want to expel the sample. This creates a tiny surface-tension effect which helps coax fluid out of the tip.
12. Slowly push down the plunger of the micropipet to the first stop. Then, continue to the second stop to expel the last bit of fluid, and hold the plunger in this position.
13. Slowly remove the pipet out of the tube, keeping the plunger pushed down to avoid sucking any liquid back into the tip.
14. Always change tips for each new reagent you need to pipet. To eject a tip, depress the large blue button on the top of the micropipet.
Your teacher may assign additional micropipet training.

Background       Part 2       Activity       Worksheet       Teacher's Guide

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