- In our previous video
we talked about Thin Layer Chromatography
and it was this technique used
to figure out how many things
you have in a sample
or maybe say the relative properties
say the relative polarity
of the things that you have in the sample
and so what you do is
you put a sample
on typically a silica gel,
which is the stationary phase
and then you put a mobile phase down here,
which in this case might be less polar
and then it's going to move
its way up the silica gel
and as it does, you can imagine,
it's going to interact with your original sample
and so parts of the original sample
are going to move up with your mobile phase
and different parts
are going to be attracted
to that mobile phase
and not attracted to the silica gel
to different degrees, you can imagine.
If there's a part of your original sample
that is more polar
then it's going to be harder to move
cause it's going to be attracted
to the stationary phase
and less attracted to the mobile phase
and so it's going to move less.
So this might be
the more polar part of your sample
as it moves from its original location
and the part that's less polar,
well it's not going to be
as attracted to the stationary phase
and so it's going to be more dissolvable
in the less polar mobile phase
and so it will go further.
So this will be the less polar part
of your original sample
and so you can see that separation
and you could come up with other insights
that we talk about that
in that other video.
In this video,
I'm gonna introduce you to
a very very very similar idea
it's just things are moving
in a different direction
and that is the notion of Column Chromatography.
What you do in Column Chromatography,
just like Thin Layer Chromatography
is let's say you have some type of vile,
some type of a column,
I guess I could say
you'll typically see it
with a little tap drawn down here
because you might wanna see
what comes out through the bottom
but what you do is you fill it
with the stationary phase
which once again is oftentimes silica gel.
So this is stationary phase
stationary phase
and if it's silica gel in this case,
silica gel
it doesn't have to be silica gel
but that's pretty common.
This is going to be very polar
so let me write this, very polar
and then you put some of your sample
at the top here.
So that's your original sample
you put it at the top
and then you have some mobile phase,
the solvent that you're going to put
on top of that.
So you're gonna do something like that
and what do you think is going to happen?
Well, your mobile phase
is going to start moving its way down
through your stationary phase
and it's going to interact with your sample.
Now what's going to happen
to the more polar components of your sample?
Well, the more polar components of your sample
are going to be more attracted
to the stationary phase,
less attracted to the mobile phase
so they're gonna move less.
So the more polar parts of your sample
might only go, maybe that far
while the less polar parts of your sample,
they'll move,
there'll be less attracted
to your stationary phase
and they'll move with your mobile phase more
and so you might have
they might move down,
down over there
and so the big takeaway,
the difference between the two
is just the direction you're moving in.
In Thin Layer Chromatography
your more polar thing is the lower dot
while in Column Chromatography,
your more polar thing
is the upper layer right over here,
this purple area right over here
and of course, all of that depends on
the polarity of your stationary phase
and the relative polarity of your mobile phase
but what I just showed you is a typical situation.
So keep in mind whether you're looking
at Thin Layer Chromatography
or Column Chromatography
which to pay attention to the direction.