Paper Chromatography Lab

Summary

This video explains the process of paper chromatography to separate pigments from spinach leaves. The materials required include chromatography paper, test tubes, a cork, scissors, spinach leaves, a coin, and a chromatography solvent (petroleum ether and acetone). The procedure involves preparing the chromatography paper, extracting pigments from spinach using a coin, drying the paper, and running the chromatography by placing the paper in the solvent. As the solvent moves up, it separates the pigments based on their solubility, revealing chlorophylls, carotene, and xanthophylls. The experiment showcases the separation of plant pigments through chromatography.

Takeaways

• 😀 You will need chromatography paper, a test tube, cork, scissors, spinach leaves, a coin, and a chromatography solvent (9 parts petroleum ether, 1 part acetone) for the experiment.
• 😀 Ensure the chromatography paper fits inside the test tube, extending from the cork to the bottom.
• 😀 Trim the chromatography paper to fit the test tube if necessary and cut the tip into a point for better solvent interaction.
• 😀 Place the chromatography paper on a paperclip hook before inserting it into the test tube for proper setup.
• 😀 Avoid transferring pigment into the tip of the chromatography paper that will touch the solvent to prevent contamination.
• 😀 To transfer pigments, use a coin to crush the spinach leaf tissue and release the pigments into the paper without damaging it.
• 😀 Concentrate the pigment in one area of the chromatography paper for better results, avoiding spreading it too much.
• 😀 Allow the transferred pigment to dry by letting it sit or using a heater before proceeding with the experiment.
• 😀 Fill the test tube with enough chromatography solvent (about 1/4 inch) to touch only the tip of the chromatography paper.
• 😀 Ensure the pigment stays above the solvent line, as the solvent will carry the pigment up the paper during the experiment.
• 😀 After the solvent reaches 3/4 of the way up the paper, remove it from the test tube to prevent the solvent from continuing to move the pigments.
• 😀 The paper will show distinct bands of pigments, such as chlorophyll a, chlorophyll b, carotene, and xanthophyll, due to their differing solubilities.

Q & A

What is the primary purpose of paper chromatography in this experiment?

The primary purpose of paper chromatography in this experiment is to separate and analyze the different pigments found in spinach leaves.

What materials are required for this paper chromatography experiment?

The materials needed include chromatography paper, a test tube, a cork, an Erlenmeyer flask, scissors, spinach leaves, a coin, and a chromatography solvent made of 9 parts petroleum ether and 1 part acetone.

Why is it important to avoid getting the pigment in the tip of the chromatography paper?

It is important to avoid getting the pigment in the tip of the chromatography paper because the tip will be submerged in the solvent, causing the pigment to dissolve directly into the solvent, which would interfere with the separation process.

How do you ensure the chromatography paper fits properly into the test tube?

To ensure the chromatography paper fits properly, you should cut it to the correct length to reach the bottom of the test tube and trim its width so it slides easily into the tube.

What is the role of the solvent in the chromatography process?

The solvent in the chromatography process moves up the paper, picking up the pigments and carrying them along at different speeds based on their solubility, causing the pigments to separate.

Why is it crucial to allow the chromatography paper to dry after transferring the pigment?

Allowing the chromatography paper to dry is crucial because the water in the spinach leaf tissue must evaporate before proceeding, ensuring the pigment is left behind on the paper for separation.

What happens if the chromatography solvent is allowed to move past the three-quarters mark on the paper?

If the solvent moves past the three-quarters mark on the paper, it will continue pulling the pigments up, potentially causing all pigments to move to the top, making it difficult to analyze the separation.

What types of pigments are typically separated in this experiment?

The experiment typically separates chlorophyll a, chlorophyll b, carotene, and xanthophyll pigments found in spinach leaves.

How does the solvent’s movement affect the separation of pigments?

The solvent’s movement causes the pigments to separate because they have different solubilities in the solvent, causing them to travel at different speeds up the chromatography paper.

Why is it important to concentrate the pigment in one area on the chromatography paper?

Concentrating the pigment in one area ensures that the pigment is properly absorbed onto the paper, allowing for clear separation. Spreading the pigment too thinly can result in poor separation and less distinct results.