Use of the pipet

Cleaning the Pipet

In order for the pipet to deliver the proper amount of solution, it must be properly cleaned.

  1. Using the appropriate technique for filling the pipet, draw distilled water into the pipet until it almost reaches the bulb. Remove the bulb and allow the water to drain. If the water drains without leaving droplets on the inside of the pipet, repeat this rinse twice more and go on to step two. If droplets cling to the inside of the pipet, clean it with detergent solution or cleaning solution. Rinse many times with tap water, then repeat the distilled water rinses.

  2. Draw a small amount of the solution you wish to pipet into the pipet. Tilt and roll the pipet so that the solution has contact with all the inside surfaces. Discard the solution from the rinses. Repeat this rinse at least once more.

  3. When you are finished with the pipet in your experiment, rinse with distilled water.



Pipetting Instructions

1. Get the appropriate amount of the solution you wish to pipet in a small, clean, dry beaker. Never pipet directly out of the stock bottles of solution. This creates a contamination risk.

2. Insert the tip of the pipet into the beaker of solution so that it is about 1/4” from the bottom. Be sure not to press the tip against the bottom of the container.

3. If you are right handed, hold the pipet in your right hand, leaving your index finger free to place over the top of the pipet. With your left hand, squeeze the pipet bulb. Press it firmly over the top of the pipet, but DO NOT INSERT THE PIPET INTO THE BULB!! Release the pressure on the bulb and allow the solution to flow into the pipet until it is above the volume mark. Do not allow the solution to reach the bulb.

4. Quickly remove the bulb and place your index finger firmly over the top of the pipet. Slowly roll you finger to one side and allow the liquid to drain until the bottom of the meniscus is aligned with the volume mark. With practice you will be able to lower the liquid very, very slowly.

5. When the bottom of the meniscus is even with the volume mark, press your index finger firmly on the top of the pipet so no liquid leaks out. Pull the pipet out of the solution and touch the tip once to the side of the container.

6. To transfer the solution, place the tip of the pipet against the wall of the receiving container at an angle of 10-20 degrees. Slowly allow the liquid to drain from the pipet. Keep the flow slow so that no droplets cling to the inside of the pipet.

7. When the solution stops flowing, touch the pipet once to the side of the receiving container to remove any hanging drops. DO NOT blow out the remaining solution. The pipet has been calibrated to deliver the appropriate amount of solution with some remaining in the tip.


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