Cleaning the Pipet

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

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

Pipetting

Always use a pipet bulb or pump to draw up liquids. NEVER USE YOUR MOUTH.
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.
Do not allow the solution to reach the bulb or pump.
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.

Pipet Bulbs & Pumps

Pump

Insert the end of a pipette into the end of a plastic pipette pump.
- Both pipettes and pumps come in different sizes. Be sure to use a pump that can "suck" the quantity of liquid you want (e.g. 10 ml pump with a 5 ml or 10 ml sterile pipette).
Next, place the tapered tip of the pipette into the liquid. The tip should be kept within the liquid during the pipetting.
Hold the pipette pump vertically with one hand--your thumb should be placed on the wheel.
Use your thumb to rotate the wheel downward. This will cause the liquid to rise into the pipette. Do this carefully and watch the meniscus of the liquid rise to your desired level.
- Remember: Measure the level of the liquid at the BOTTOM of the meniscus.
Next, take the tip of the pipette out of the liquid and move the entire apparatus to the place where you desire to put the measured liquid.
Holding the pipet in the vertical position above the selected container either slowly turn the ridged wheel upward to add a specific volume, or press the lever on the side of the pump to empty the entire pipet into the container.
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.

There are 3 areas on the bulb that can be squeezed: A (aspirate), S (suck) and E, or - (empty). Identify these areas and give them a quick squeeze just to check it out.
Put a pipette into the bulb, under area S. Insert the cotton-filled end carefully.
Always hold the pipette with the open end down to prevent solutions from entering the bulb.
Be aware that there are different graduations on different sizes of pipette. Make sure you use the correct size!
Squeeze the bulb while holding area A. This creates a vacuum.
Put the end of the pipette tube into the liquid, and squeeze area S. Watch carefully, the liquid rises quickly. Fill the pipette to a level just higher than you need for the experiment. Release area S.
Put the pipette tube into the area you want to dispense the liquid. Squeeze area E to release the fluid. The harder you squeeze, the faster the liquid comes out.
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.