1. Chromatography

2. Learning Intention… Success Criteria…
Students will be able to… Identify chromatography, how it works, the different types and how it used in the real world. Students will carry out a small practicum, determining ink samples.
Success Criteria…
Students can understand the meaning of chromatography and look at how ink in separated.

3. What is Chromatography?
Lets look at your prior knowledge.
“What do you know about Chromatography?”
See if you can enter one thing you know about chromatography, have a go!

4. What is Chromatography?
Chromatography is a way to look at complex mixtures by separating them into their components. The separation of a mixture into its components is a physical process, i.e. because the components of the mixture are not chemically combined, they can be separated by physical means.

5. What is Chromatography used for?
Real life examples:
Pharmaceutical companies- determining amounts of chemical found in products.
Hospitals- detecting blood and alcohol levels in patients.
Law enforcement- comparing samples found at crime scenes from suspects.
Environmental agency- determine the level of pollution in water supplies.

6. When do we use Chromatography?
Discussion… Looking at ’what chromatography is used for’, write what you think about when we might use chromatography. Different scenarios. 3 people to share their answers.

7. What are the different types of Chromatography?
Liquid Chromatography – separates liquid samples with a liquid solvent (mobile phase) and a column composed of solid beads (stationary phase)
Gas Chromatography – separates vaporized samples with a carrier gas (mobile phase) and a column composed of a liquid or of solid beads (stationary phase)
Paper Chromatography – separates dried liquid samples with a liquid solvent (mobile phase) and a paper strip (stationary phase)
Thin-Layer Chromatography – separates dried liquid samples with a liquid solvent (mobile phase) and a glass plate covered with a thin layer of alumina or silica gel (stationary phase)

8. What are the different types of Chromatography?
Paper Chromatography
Can be used to separate the components of inks, dyes, plant compounds (chlorophyll), make-up, and many other substances
Thin-Layer Chromatography
Uses thin plastic or glass trays to identify the composition of pigments, chemicals, and other unknown substances.
Liquid Chromatography
Used to identify unknown plant pigments & other compounds.
Gas Chromatography
Used to determine the chemical composition of unknown substances, such as the different compounds in gasoline shown by each separate peak in the graph below.

9. How does Chromatography work?
Different inks have different properties, such as how much they can be dissolved in solvents. When you place chromatography paper into the solvent, the solvent begins to move up the paper. As the solvent rises, it dissolves the ink on the paper and separates the ink into its components. The farther the ink travels, the more it is attracted to the solvent.
How does Chromatography work?

10. Paper chromatography
How many colors make up the pens that you use? You may think that your black marker is only black, but with this experiment you will be able to extract the different colors that make up the color of your pen.

11. Paper chromatography Ink is placed on filter paper (stationary phase)
Water (mobile phase) is soaked up & passes through the filter paper (stationary phase)
Water (mobile phase) breaks down the ink components
Water (mobile phase) carries the individual components of the ink a certain distance along the filter paper (stationary phase), depending on their attraction to both of the phases (water & filter paper)

12. Example of paper chromatography.

13. Tape – Label with marker
Experiment
Resources: coloured pens, coffee filter strips, skewers, beaker, water, pencil
Draw a line with pencil, 1cm from the bottom of the coffee filter strip.
Next mark separate lines or dots onto the pencil line of each sample coloured pen.
Pour 2cm of water into a beaker and sit a skewer on the top of the beaker.
Attach the coffee filter strip to the skewer so it just touches the water.
Leave for 15 minutes for ink to separate.
Examine the patterns.
Pencil
Filter Paper
Ink Mark
Tape – Label with marker