Volumetric (transfer) Has been calibrated to deliver only one volume. Do not blow out last drop (there are no etched rings).

Transcription

1 Lab 3 Pipette Lab

2 Purpose: The purpose of this lab is to learn how to pipette correctly so that accurate reagents can be made. The materials needed for this lab is as follows:

3 Volumetric (transfer) Has been calibrated to deliver only one volume. Do not blow out last drop (there are no etched rings). Very accurate measurements can be made.

4 Ostwald (transfer) Ostwald is a special type of volumetric pipette. Used to measure viscous fluids. Looks like volumetric except bulb is closer to delivery tip. Etched ring means to blow out last drop.

5 Serologic (measuring) Blow out last drop. To deliver entire volume, must deliver to tip. Slightly less accurate than Mohr. Can measure many volumes.

6 Mohr (measuring) Graduated pipette with marking used to measure various amounts of fluid. Do not blow out last drop. Note that graduations do not go to tip. Entire volume has calibrations. Used to deliver many volumes.

7 Test Tube Rack Pipette Bulb Empty Erlenmeyer Flask

8 Kim wipe Test tubes

9 Colored Solution in 125 Erlenmeyer flask Water in 125 Erlenmeyer flask

10 1. Select the volumetric pipette, and hold it in your dominant hand.

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12 2. Place the pipette bulb in your nondominant hand and squeeze it.

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14 3. Attach the pipette bulb to the mouth of the pipette.

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16 4. Place the tip of the pipette into the fluid and draw up fluid by releasing pressure on the pipette bulb.

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18 5. Make sure to draw up a little excess fluid pass the fill line.

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20 6. Place your index finger of your dominant hand over the top of the pipette. Apply pressure so that the fluid does not leak from the pipette.

21 Picture to be added

22 7. Wipe the tip of the pipette with a Kimwipe or paper towel.

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24 8. Adjust the meniscus to the desired line of the pipette by gently releasing the pressure applied by your index finger until the liquid starts to flow out slowly.

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26 9. Deliver the fluid to the 1 st test tube. Hold the pipette vertically, and let it drain slowly.

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28 11. Use the bulb to blow out last drop if there is an etched ring on the pipette.

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30 The etched rings are located at the top of the pipette. It goes all the way around the pipette, and looks like the glass was scratched all the way around.

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32 Be careful not to confuse the etched rings with the company emblem that is also painted on the top of most glass pipettes.

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34 Do not blow out last drop if there is not an etched ring on the pipette.

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36 12. Select the ostwald pipette, and hold it in your dominant hand. Repeat steps 2-10.

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38 13. Select the serologic pipette, and hold it in your dominant hand.

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40 14. Repeat steps 2-10,

41 Pipette 1-5 ml (size may vary) in tube 3. The disposable serologic pipette that is used is a blow out pipette. There are no etched rings, because it is not cost effective for disposable pipettes.

42 15. Select the mohr pipette, and hold it in your dominant hand.

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44 15. Repeat steps 2-10.

45 Pipette 4 ml of fluid in tube 4. The fill line is at the zero line.

46 16. Select the mohr pipette and hold it in your dominant hand.

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48 17. Repeat steps 2-10.

49 This time, do not go all the way to the fill line to same time. Only pipette past the 4 ml fill line, and pipette 6 ml in tube 5.

50 18. Pour the liquid in all five tubes back into the beaker of colored solution.

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52 19. Select the mohr pipette, and hold it in your dominant hand.

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54 20. You are going to repeat steps 2-10.

55 Practice dispensing 10 ml of colored solution into five different test tubes.

56 22. In tube 1 place 1 ml, place 2 ml in tube 2, place 3 ml in tube 3, place 1 ml in tube 4, and place 3 ml in tube 5. Because the mohr pipette is not calibrated to the tip, discard the remaining fluid into your beaker of colored solution.

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58 When you use the full 10 ml of fluid, there will always be a little fluid remaining. Discard the remaining fluid into your beaker of colored solution.

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60 23. Pour the liquid in all five tubes back into the beaker of colored solution.

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62 24.This time, decant all tubes very well or it will affect your next step. To decant tap tubes gently on your

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64 25.If necessary put paper towel in tubes to remove excess fluid.

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66 Step 2: Seria1Dilution. 1. Place 5 tubes in a test tube rack.

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68 2. Add 1 ml of dilutent (water) to tubes 2-5.

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70 3. Add 1 ml of colored solution in tubes 1 and 2. Tube 1 will remain a 1:1 dilution and nothing else will be added. Tube 2 should have 2 ml ( 1 ml of dilutent and 1 ml of colored solution) making it a 1:2 dilution.

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72 4. Mix and transfer 1 ml of mixture from tube 2 and place it in tube 3. Tube 3 should now have 2 ml.

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74 5. Mix and transfer 1 ml of mixture from tube 3 and place it in tube 4. Tube 4 should now have 2 ml.

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76 6. Mix and transfer 1 ml of mixture from tube 4 and place it in tube 5. Tube 5 should now have 2 ml.

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78 7. Mix and transfer 1 ml of mixture from tube 5 and place it back into the original large beaker of colored solution.

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80 8. When you are finished, put your tubes in a special rack and bring it to the teacher for approval. Also, bring your lab sheet for a stamp of approval by the teacher.

81 1:1 1:2 1:4 1:8 1:16

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83 Refer to the teacher for disposal instructions

84 Results Part 1: Fill in the blanks for 1 and 2. Check respective boxes once you have completed each step.

85 Conclusions Write a sentence about your pipette lab experience, good or bad.

86 Questions Answer the questions. Use short answers please

87 Performed by Samarra Kinche and Jeremiah Umoh Class of 2009