In this video, you're going to learn
how to use a transfer pipette.
Before watching this video, please make sure you've seen the meniscus video.
This is a transfer pipette.
It's easily recognizable by the wide section located halfway up.
Transfer pipettes are used to transfer one specific volume very precisely and accurately.
Each transfer pipette can only transfer one volume
so different pipettes can be used for different volumes
Printed on the wide section of the pipette is a number.
This indicates the volume that it can transfer.
This number is also located near the top of the pipette.
This printed line near the top of the pipette indicates where the bottom of the meniscus should be
when the correct volume is in the pipette.
Begin by checking the pipette for any damage.
Pay careful attention to the tip.
If you notice any damage on any part of your pipette
report it to your TA, and get a new, undamaged, transfer pipette.
Hold the pipette near the top end with your dominant hand.
You should be holding it with your fingers
and not a fist because that can cover the graduation.
You should also make sure that your index finger is free to move
without dropping the pipette.
Now take your pipette bulb in your non-dominant hand, and give it a squeeze.
Place the open end, called the taper, on the top of the pipette
and place the tip of your pipette into the deionized water.
Make sure your pipette is vertical, and slowly release your grip on the pipette bulb.
You should notice the water begin to rise up the bottom of the pipette.
If this is not happening, adjust the seal on the pipette bulb by wiggling
it around until you notice the water begin to rise.
a good way to create a good seal is to
create constant force down on the pipette bulb,
but release at the sides.
Fill your pipette until it is roughly one third of the way filled
with the deionized water.
Then quickly remove the pipette bulb, and replace it with
your finger.
You may feel more comfortable to hold it with your thumb, but don't do this.
Holding it with your finger is more precise.
Now, remove your pipette from the deionized water,
and tilt it horizontally.
Remove the transfer pipette from the water, and
tilt it so that it is on a nearly horizontal angle.
Hold it with both hands to prevent it from breaking
and rotate it gently.
Do this to get the water along the entire inner surface of the pipette, including a few
centimeters above the top graduation.
Hold your pipette vertically, and tilt the waste beaker.
Allow the tip of the pipette to touch a clean dry area beginning at the top of the beaker.
Release your index finger from the top of the pipette,
and allow it to drain at its own pace into the waste beaker.
You don't want to force it out faster,
as the capillary action will help to remove all of the liquid from the pipette.
Once it is drained, hold it in position,
for ten seconds to make sure all the liquid has reached the base of the pipette.
Now, with your free hand, grab your pipette bulb,
and squeeze it on the top of the pipette.
This is called blowing it out.
This allows for the small amount of liquid remaining in the tip to be
forced out.
Repeat this process two more times with deionized water
and then three times with the solution you want to transfer.
Make sure that you never put your pipette directly into the stock solution.
I have transferred some of the stock solution into a separate beaker
to prevent contamination.
When you finish rinsing your pipette,
you should have rinsed it three times
with deionized water, and three times with the solution you are going to use.
Your pipette is now clean, and ready to be used.
When using the transfer pipette to measure and transfer a solution,
use the same technique used to rinse it.
Squeeze the pipette bulb with your non-dominant hand,
and place it on the top of the pipette
and then place the pipette into the solution.
Slowly release your grip on the pipette,
and allow the solution to rise up the stem.
You'll notice that it moves faster through the thinner section
and slower through the wider section.
You'll have to be aware of this, as you'll have to fill the pipette
above the wide section, so make sure to
anticipate an increase in speed.
You may find that you completely released your grip on the pipette
bulb, but your transfer pipette is not yet filled.
To fix this, gently rest the pipette on the bottom of the glassware
and replace the pipette bulb with your finger.
Squeeze the pipette bulb again,
and place it back on the top of the pipette,
and continue filling it as before.
You'll want to fill your pipette to just a few centimeters above the top graduation.
Replace the pipette bulb with your finger,
and then lift your pipette out of the solution.
Wipe down the outside of your pipette.
with a Kimwipe. This removes access solution from the outside being transferred.
Now, place the tip of your pipette onto the side of your solution
beaker, and begin to drain.
Drain slowly, until the bottom of the meniscus lies exactly on the top graduation.
Once you've finished draining your solution,
to the line on the pipette, touch the tip of the pipette to the side of the glassware
to remove any remaining drops.
Then move it over to your receiving vessel.
If at some point you realize that you've drained below the graduation,
just fill it up again as shown earlier.
Now, place the tip of your pipette on the side of the receiving vessel
and begin to drain your solution.
via lifting your finger, and relieving the pressure.
Allow the solution to completely drain out of the pipette.
Once completely emptied, hold the position for ten more seconds to any more solution
to reach the bottom of the pipette.
Once this is done, gently touch the tip to a clean location on the receiving vessel,
and remove the pipette from the flask.
Do not blow out the solution remaining inside the tip like you did when rinsing.
The transfer pipette is calibrated for this residual liquid
adding it to the transferred solution will result in an incorrect volume being transferred.
Your solution has now been measured and transferred,
and the pipette's job is done.
Now you need to clean it before putting it away.
To do this, you use the same process used to rinse it initially.
Only instead of using the ionized water in your solution,
you should first rinse it three times with tap water, then three times with the ionized water.
If at some point, you've gotten liquid in your pipette bulb, you need to clean it.
Start by removing the taper,
and rinsing it thoroughly with deionized water into the waste beaker.
Set it aside to dry.
Now you want to empty the pipette bulb as much as possible into the waste beaker.
Then you want to rinse this too with deionized water.
Do this thoroughly to get rid of any chemical contamination.
and again, empty it into the waste beaker.
You'll have to set this pipette bulb aside and use another one to continue your experiment.
Now that you've learned to properly use a transfer pipette,
here are some tips to keep in mind.
Never pipette by mouth.
You should never put anything in the lab in your mouth, no matter how clean it is.
There are pipette bulbs available so that you can use them.
You should always use your index finger, and never your thumb.
Even though this may feel more comfortable,
you have better control with your index finger.
When filling or draining your pipette,
make sure to hold it vertically.
Holding it on a slant can let air in and alter your volume reading.
Keep the tip of your pipette submerged when filling your pipette.
Keeping it too high can let air in, and again, alter your volume.
When draining your pipette, make sure that the tip is not submerged in the draining solution.
This can prevent some of the solution from emptying the pipette, again, altering your volume.
Never use soap to clean your pipette.
unless specifically instructed to do so by your TA
Soap can leave an invisible film inside the pipette, which can alter your results and contaminate your solution.
After transferring your solution, make sure not to blow out the solution remaining in the tip
because this too, can alter the volume of the liquid you transferred.
Never shake the pipette to get out excess liquid.
Let it drain on its own.
Shaking it is dangerous and will accomplish nothing.
It takes time to refine your pipetting skills
but by following the instructions and rules that I've told you
you can become a pipetting master in no time.