Hi there! I'm Jayme dyer this is a micropipette
and it's the most important tool in the molecular biology lab.
I randomly pick this issue of the scientific journall Nature
and all of these articles did at least some part of their research using
micropipettes.
A micropipette transfers tiny volumes of liquid.
It does this by drawing up the liquid like this.
Of course, in lab, we don't transfer liquids using straws
we use pipettes. Pipettes transfer milliliters of water while micropipettes
transfer microliters of water.
Micropipettes come in a few different sizes for the same reason we use
different scales to weigh different types of
animals. A laboratory scale is sensitive enough to weigh a mouse
but not an elephant. Similarly, this micropipette is sensitive enough to
pipette five and a half microliters but it doesn't have the capacity to
pipette 500 microliters. These are the most common ranges for
micropipettes though there are other ones as well.
We name them according to their range's upper limit.
This is a p20, p200, and a p1000. If I need to transfer 800 microliters,
I'll use a p1000. but if I need to transfer 30 microliters
I'll use a p200. You can tell what the range of a
micropipette is because it's written on it somewhere,
usually on the plunger but not always.
When you use a pipette you make sure to draw up the right volume of liquid by
looking at where the liquid is on the pipette.
But micro pipettes transfer such a tiny volume that you can't be accurate just
by looking. So for micropipettes, you set the volume
and the micropipette will draw up exactly that much
to set the volume. On a micropipette you turn this dial here and these numbers
show you the volume that it's set to. The unit is always microliters so this
p1000 is set to 650 microliters and this p200 is set to 85 microliters.
But be careful, because for micropipettes with a range of 20 microliters or less,
the volume display includes an extra number. It's usually red
which represents decimals. This is 12.5 microliters
not 125 microliters.
Never set the volume above or below a micro pipette's range.
It will break it and these things are expensive!
If I didn't have a straw I could transfer the liquid like this.
But now this is contaminated with my spit.
The opening of a micropipette is a little bit like a mouth and it's usually
pretty dirty and it's not designed to hold liquid
anyway. Never put a micropipette directly into
liquid.
Just like I used a straw the micropipette needs something clean to
hold the liquid that's where this comes in. It's called a
tip. The tip is clean and it holds all the
liquid.
different micropipettes need different sized tips.
There are a couple of ways to tell which tips fit on which micropipettes.
Sometimes the tip box says what size tips they're for but
not always. Often the color of the plunger is the same as the color of the
tip, but not always.
You'll know if you have the right size tip because if it's not the right size
it won't fit. You use the plunger to draw up and
dispense the liquid. But wait! There's a trick to it. When you first
push down the plunger, it goes all the way to the first stop.
But if you push harder you can push it down to the second stop.
The second stop is there because when you dispense the liquid,
if you only push down to the first stop a tiny bit of liquid stays in the tip.
pushing down to the second stop squirts the rest of the liquid out so you are
sure that you transfer all the liquid in the tip. The second stop is used only for
dispensing liquid which means
never use the second stop to draw up
liquid. To draw up liquid push the plunger to the
first stop insert the tip into the liquid.
Then, slowly release the plunger to dispense the liquid.
Push the plunger to the second stop. Now in order to draw up liquid, you have
to push the plunger down first. But if you do that when the tip is in
the liquid, you'll blow bubbles. So, always push the plunger before
putting the tip in the liquid. When you're drawing up or dispensing the
liquid, if you push the plunger button too hard you can squirt your liquid all
over the place. So, push the plunger button slowly.
Once you've transferred the liquid, your tip is dirty. If you use this tip to
transfer a second liquid you'll contaminate the second liquid.
To get rid of the tip, use the ejection button which lets you easily eject the
tip. Make sure you eject it into an
appropriate container. That's it! Now you're ready to use a
micropipette and maybe one day you'll be the one publishing cool research in a
journal like Nature!