Hello All! Recently, I took part in a Chromatography Lab.
Using Chromatography to Identify Pigments in Green and Non-green Leafs
Purpose: The purpose of the chromatography lab is to identify the pigments found in green and non-green leaves.
Background: Photosynthesis is the production of sugar, oxygen, and water through a chemical reaction that uses carbon dioxide and light energy. Photosynthesis can not be performed by all living things but photosynthesis is vital to all life because Glucose is needed for energy. Within the essential reaction of photosynthesis, color names pigments that result from the absorption of certain colors of lights and the reflection of other colors of light. Some examples of pigments include chlorophyll which reflects green, carotene which reflects orange, and xanthophyll which reflects yellow. Chromatography is a technique used to separate pigments found in plant cells that can identify the specific pigments that activate photosynthesis. When chromatography is used to separate pigments, characteristics of pigments start to unfold such as the attraction between the pigment (solute) and the solvent, the attraction between the solute and the chromatography paper, and the Rf (relative mobility factor). The Rf is a ration of the distance between the solute and the solvent that is a determining factor in identifying pigments because Rf values are consistent.
Hypothesis: If the green and the non-green leaf contain similar Rf values, then the same pigment is present in both the green and non-green leaf.
Data
Questions
1. What is the basic importance of chromatography?
The basic importance of chromatography is to separate mixtures into individual substances.
2. What factors allow chromatography to happen?
The factors that allow chromatography to happen are the chromatography paper, the presence of pigments, and the attraction between the solute and the solvent.
3. What purpose does the chromatography paper have in this experiment?
The purpose of the chromatography paper is to test whether or not the solute (pigments) attract to the solvent.
4. What is the purpose of the solvent?
The purpose of the solvent is to look at the efficiency and speed of each pigment when the pigment is exposed to a favorable solvent.
5. What does Rf value stand for?
Rf stands for the Relative Mobility Factor.
6. How do you think that the Rf value is useful to scientists?
The Rf value is useful to scientists because Rf values remain constant allowing pigments to be easily identified.
7. What does Dunknown signify?
The Dunknown is the distance traveled of the solute.
8. What does Dsolvent signify?
The Dsolvent is the distance traveled of the solvent.
9. How many pigments were you able to identify from the GREEN leaf chromatogram?
In the green leaf, I was able to identify three pigments. The pigments were xanthophyll (yellow) with an Rf value of 0.927, a type of chlorophyll (dark green) with an Rf value of 0.873, and another type of chlorophyll with an Rf value of 0.818.
10. How did a GREEN leaf chromatogram compare to a NON-GREEN leaf chromatogram?
In the non-green leaf, I was able to identify two pigments. The first pigment was chlorophyll (light green) with an Rf of 0.758 and xanthophyll (yellow) with an Rf of 0.879.
11. What else did you find out about pigments and photosynthesis?
I found out that within plant cells, there are primary pigments and accessory pigments. Primary pigments are the visible pigments found in leaves that give off the color of the leaf but accessory pigments are the colors that are not directly visible but are a pigment that is present in the leaf.
12. What is one more question you still have?
A question I still have is, why do pigments have similar Rf values?
Alysa's AP Bio Blog 
Hi Alysa, I really like your post because you really are clear and concise with your information about the lab. I also like how you included a clear picture of the results, included text on the photo, and added a ruler to show how far the pigments traveled. To improve, perhaps you can add a table with results and the Rf values. I believe to answer your question, pigments have similar Rf values if they are given the same conditions and factors, such as the same paper, length of the paper, and solvent. Overall, nice work teammate! Keep up the good work!
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