1. Practicing with a P-20
   
   
   1. Label two empty reaction tubes A and B with a permanent ink marker, if not already labeled.
      
   2. Add the amounts of solutions I, II, III and V to tubes A and B as shown in the table below.
      
      

      Solution Volume in Each Tube
      Reaction Tube	Solution I	Solution II	Solution III	Solution IV	Solution V	Total in Tube
      A	4 µL	5 µL	2 µL
      B	6.5 µL	2.5 µL			2 µL

      
      
   3. Spin tubes A and B in the microcentrifuge for 1-2 sec to pool the solutions.
      
      > REFER TO PREVIOUS CENTRIFUGE INSTRUCTIONS
      
      

   4. Add up the total volume of liquid in Tube A. AS A CHECK OF YOUR TECHNIQUE, set the micropipet to that volume and withdraw all of the liquid in tube A. The contents should just fill the tip -- no air space at the bottom of the tip; no leftover liquid in the tube. Discard liquid and tip into waste beaker     5. How much should be in tube B? __________ Check your technique by setting the pipettor to the correct volume and withdraw all (hopefully) the solution in tube B.

   
   
2. Practicing with a P-200
   
   
   1. Label an empty reaction tube C, if not already labeled.
      
      
   2. Add the amounts of solutions I, II and IV to tube C as shown in the table below.
      
      
   
   

   Reaction Tube	Solution I	Solution II	Solution III	Solution IV	Solution V	Total in Tube
   C	20 µL	40 µL		100 µL

   
   
   3. Spin tube C for 1-2 sec. (Be sure to balance your tube.)
      
      
   4. Check the accuracy of your micropipeting technique with the P-200. Set to ________ µL and withdraw the contents of tube C.
      
      
      
      
3. Practicing with a P-1000.
   
   
   1. Label an empty reaction tube D if not already labeled
      
      
   2. Add the amounts of solutions III and V to tube D as shown in the table below.
      
      
   
   

   Reaction Tube	Solution I	Solution II	Solution III	Solution IV	Solution V	Total in Tube
   D			200 µL		550 µL

   
   
   3. Spin tube D for 1-2 sec. (Be sure to balance your tube.)
      
      
   4. Check the accuracy of your micropipeting technique with the P-1000. Set the pipet to ______ µL and withdraw the contents of tube D.
      
      
   
   
4. Practicing with all micropipets
   
   
   1. Label an empty reaction tube E, if not already labeled.
      
      
   2. Fill in the blanks in the following chart. Indicate on the line "P-_____" the appropriate micropipet to be used for each sample. Then write in the three boxes below each line, the numbers that should be dialed to give you the indicated volume.
      
      
      

      Reaction Tube E	Solution I	Solution II	Solution III	Solution IV	Solution V
      Volume:	15 µL	105 µL	12 µL	38 µL	350 µL
      Micropipet: (P-20,P-200,P-1000)	P-_____	P-_____	P-_____	P-_____	P-_____
      Micropipet setting

      
      
      
   3. Add the volumes of solutions I-V indicated above into tube E, using the appropriate micropipet.
      
      
      Check the accuracy of your micropipeting technique with the P-______. Set the pipet to ____ µL and withdraw the contents of tube E.
      
   
   
   

• Assessment X
  
  1. Obtain a reaction tube with 40 µL of water.
     
     
  2. One at a time, each student in a group of 4 should withdraw 9 µL of water and expel the 9 µL as one drop on a piece of waxed paper. When each student has had a turn, compare the four drops. Are the drops the same size? If yes, great! Continue to step 3.
     If not, why not? Try again, carefully coaching each other.
     
  3. The teacher then will withdraw the last 4 µL.
     
     
• Assessment Z
  
  1. Obtain a tube with 10 µL of glycerol.
     
     
  2. Each student in a group of 4 should withdraw 2 µL from the tube and place it on a piece of waxed paper as separate drops. Compare drop sizes
     
     
  3. When everyone in the group is finished, call the teacher over to check your results by withdrawing the last 2 µL.
  
  
  
  

• Remove liquid from all reaction tubes A-E and the two assessment tubes. DRY OUT TUBES and leave for next class.
  
• Dispose of designated materials as outlined by your instructor.
  
• Leave equipment as you found it.
  
• Check that your work station is in order.
  
• Wash your hands.

Activities Exchange Index