Lab 1 – Working With A Pipette
Introduction
During this lab we had the chance to take some fun and educated measurements with a line of pipettes known commonly as the Eppendorf line of pipettes. These pipettes were unique due to the change in color of the top knob that we so graciously got to push down. Now why different colored pipettes to begin with? It’s just to confuse you of course.. Just kidding, it’s for establishing the different sizes and amount of liquid you can suspense with each pipette.
Now these clever little devices will automatically take-up the selected volume you tell it to do so. However, don’t mix up the colored tips with the colored button at the top of the device. That’s a no no!
For example, above you can see that there is a yellow tip at the end of the apparatus that matches the color of the knob that handsome man is holding. Thus, the purpose of this lab was to see that not only could we follow directions but if the accuracy of the pipettes given held true to the device. Which also taught us how to correctly suck up small amounts of liquid. To test this, we had taken several different measurements of colored water then added them up and sucked all the water up to see if it was the same. I was certain that the device couldn’t be all that accurate but we will see.
Methods and Materials
In this lab we used only a short variety of equipment which includes the Eppendorf line of pipettes as well as the tips in which you discard. The small vials of colored liquid (Blue, Green, Yellow and Red), a beaker and a holding tray for the vials. We had used the beaker as a waste bin for any discarded material which primarily was the used tips to the pipette.
For the experiment itself, we used a pipette as shown above to learn how to correctly measure small amounts of liquid. In order to use the pipette correctly the following procedures need to be met.
First: Notice how the pipette has a button at the top and if pressed, the button has two depths it reaches with a small click or stop that ends at each. The first click allows you to suck up any liquid once submerged. You then release you thumb upward, housing the liquid in the tip that you had put on.
Second: To release the liquid, you use the button at the top again and push to the first click then pause for a moment and push till the second click is done. This squeezes all remaining liquid out of the tip. The second push is only for releasing!! Do not suck up liquid with second click.
Third: You have to dispose of each tip after each usage. There generally is a button in the middle or a knob to push down to this. Discard them in the beaker that was mentioned earlier.
Now after understanding the pipette and how to correctly use it. We had done a few test that were given to test the accuracy of this device. To do this we had 4 colors like listed above.
We then took a specifically small volume out of each vial using a pipette of 10-100 microliters and dropped it in a blank test tube, each color added to the amount. After we changed up the volume, we added the amount of single volumes together and changed the amount on the pipette to match the new volume (you can do this with a button at the top and twist the colored button to the appropriate amount). We then sucked up the liquid to the listed value to see if we could be accurate and precise with our measurements. Once mastering this we upgraded to a thousand microliter pipette with a blue to like shown in top right photo. We were tasked to drop different volumes of colored liquid onto a film sheet. Just like before, we did several single test then added the volume up and sucked it back up to see if it had matched the volume we had calculated.
Results
Call me Robin Hood with all this precise and accurate information!
Tube
|
Red
|
Blue
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Green
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Yellow
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Total
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Color
|
#1
|
200µl
|
300µl
|
0
|
0
|
500µl
|
Purple
|
#2
|
0
|
0
|
250µl
|
200µl
|
450µl
|
Dark Green
|
The chart above shows two test using a 1000 microliter pipette to see if we can add single volumes and suck up the after math, matching it with the correct volume. This was the first set of test just to get a feel for what was going on.
Our results shown with the pictures above prove that after adding all the single volumes together then adjusting the pipette, we had the correct amount sucked back into the tip. Thus we were precise and accurate after completing this a few times.
Discussion
I was actually surprised that the pipette sucked up as much as it did. So my hypothesis was wrong and the pipette is a very reliable tool. This lab was very simple but I learned a lot on the use of a pipette. This I feel is going to be critical for the labs to come.
