JOAN CARTAN-HANSEN, HOST: Chemists can help us discover things that our eyes can't see.

Here's an experiment you can do at home to let you do just that.

(Music) Chris Saunders and Christina Mottishaw are chemists.

They're in my kitchen to show you how to do an at-home chemistry experiment about chromatography.

(sound effect) CHRISTINA MOTTISHAW, CHEMIST: Chromatography comes from two Greek words, chroma meaning color photography, meaning paper chromatography is a technique that scientists use to separate things out that on a tiny little molecular level are really different.

But on a big level, like what we see with our eyes, don't look that different.

Things like coffee paper or coffee filter have a special pores inside of them to help us separate things out by their tiny little characteristics rather than their big characteristics that we can see with our eyes.

For instance, things like markers that we use at home are made up of ink and dyes and those ink and dyes are different on the tiny little molecular level than they are with what we can see on our eyes.

Chromatography can help us see what's on the inside of these markers and maybe even see if some of these markers aren't just one color, but many colors.

We can test that by using some simple techniques.

Get some coffee paper, coffee filter, some water-soluble markers and some water.

To do this test.

CHRIS SAUNDERS, CHEMIST: It's important to pick the water-soluble markers.

So permanent markers don't dissolve very well in water, which makes them so hard to clean off surfaces.

So, for this, since we're using water as a solvent to move these inks and dyes that Christina was talking about, we need markers that will be compatible, compatible with that.

So, make sure that your markers say water soluble or washable markers and those will work well um, with water.

So, Christina is putting some of the green marker on there and think about, well, is that all one component that makes it green?

Is it more?

You might think about, well how, what colors do we mix to make green?

But we'll be able to see if there's actually a mixture of components in there as we add the water.

MOTTISHAW: So, once you have your marker on top and ready to go, I recommend that you use two layers because the water moves through these things really fast.

And make sure you put it on top of something else to catch the extra water that's gonna fall through.

Grab your water and a spoon.

And then starting in the middle, slowly, slowly pour water until it gets to where your marker is and then you can start see it flow through the filter paper.

If you wait just a couple, it'll flow its way all the way down.

SAUNDERS: So, you can observe that even though Christina poured the water at the top, the water is gonna travel through that filter paper kind of slowly as it gets from the top there down along, but gravity is gonna pull, pull that down.

So, if I'm observing this and I'm looking at this, it looks all one color to me.

So, I would say that probably just one type of ink is used to make, um, the color for that particular marker.

But we might not see that with all the other markers.

So, we'll need to, we need to do some further testing.

CARTAN-HANSEN: Next, they try the same experiment but with black ink.

SAUNDERS: So what might make up that black ink?

Is it one compound?

Is it multiple compounds?

Um, cuz now we're gonna add the water to it and we're gonna see if there's anything in there to separate or if it's just that one same black color.

MOTTISHAW: So, take a minute here to make a prediction.

Chris, what do you predict?

SAUNDERS: I have changed printer ink many times and I can tell you that for black printer ink, it's not just black ink that there are other colors in there.

So, I think with these markers, I think we're gonna see more than one thing.

MOTTISHAW: All right, let's do it.

SAUNDERS: So, I will say in terms of observing this, that it doesn't quite look like black ink as it starts to separate.

MOTTISHAW: To me it sort of looks like our green ink that we did over here.

SAUNDERS: It does, it looks really similar to the green.

So, and the more that it separates, the more that I can start to see that other color.

So, I still see some of the dark ink, but there's definitely some green that's showing up as it separates.

MOTTISHAW: And if you look directly at the top, what I'm seeing is some pink where I put my smiley face, so that dark black color turn to a much lighter color that almost looks pink.

So I'm seeing pink in the center, black around the edge and green on the very, the very bottom part of our, of our coffee filter.

SAUNDERS: Yeah.

So that certainly suggests that there's more than one type of component that makes up that, uh, black ink.

As I talk about this in terms of matching inks, this is not dissimilar to, um, a forensics lab that might be trying to compare ink on paper and whether it came from a particular source.

These are some of the techniques, probably not with, with coffee filter paper, but with other things to separate this out to identify is it likely that it came from the same, from the same place?

MOTTISHAW: Yeah.

So, you can try this at home, not only with coffee filter paper, but you can use regular paper, paper towels, napkins.

All you just need is a little bit of water and something to filter it through.

CARTAN-HANSEN: If you want to learn more about chemistry, check out the Science Trek website.

You'll find it at ScienceTrek.org.

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