Chromatograhy High School Experiment

Name: Megan
Grade: 2nd Year High School - Home School
Texas, USA
Science Category: Biology - Botany

1. Gather Materials.

2. Collect leaves in plastic bags throughout the city of San Angelo.
3. Collect both deciduous plant samples and broadleaf evergreen plant samples.
4. Identify and record location of sample taken using GPS (Global Positioning System).
5. Take pictures of leaves with camera for identification.
6. Tear each set of leaves into several pieces, making sure to thoroughly crush the leaves to release pigments in leaf cell.
7. Place them in a 16 ounce glass jar.
8. Add just enough 91% Isopropyl alcohol to cover leaf pieces.

   

9. Cover the containers with foil or plastic wrap to keep the alcohol from evaporating.
10. Put the containers in a 9X13 pan and add hot water.

11. Let sit overnight. The alcohol will turn green as the pigments from the leaves are absorbed into it.
12. Cut a strip out the middle of a coffee filter, one inch white, for each of the leaf samples.
13. Tape one end of the paper to a pencil, and suspend it across the container, with the other end just touching the alcohol and pigment mixture. A bit of the mixture will travel slowly up the paper.
14. After about 30-90 minutes you should be able to see the "green" color break up into several different colors as the different pigments begin to travel up the paper and separate. After three hours, remove the strip and allow to dry.
15. Record observations
16. Repeat steps 10-13 for each leaf sample.

17. Cut a strip of the drawing paper, one inch wide, for each of the leaf samples.
18. Repeat steps 10-13 using drawing paper to test each leaf sample.
19. Cut a strip of Viva paper towel, one inch wide, for each of the leaf samples.
20. Repeat steps 10-13 using Viva paper towels to test each leaf sample.

Data - click on images to enlarge

Deciduous Group	Broadleaf Evergreen Group
Mexican White Oak	Texas Mountain Laurel
Texas Red Oak	Texas Sage
Mesquite	Yucca
Ash	Live Oak
Poinciana	Palm Tree
Cottonwood	Viburnum

Data Analysis

I chose to run my test using three types of chromatography papers. Originally I was going to use only coffee filters to test my samples, but I was not satisfied with the results and used the other options of Viva™ paper towels and drawing paper. I was very content with the results, as well as the separation of the pigments.

Overall, the results in comparison of the deciduous and the broadleaf evergreens were very similar. Both the broadleaf evergreens and the deciduous contained the pigment chlorophyll, as well as, xanthophylls, carotenoids, and anthocyanins. All the samples in the deciduous group showed all pigments. All the samples but one in the broadleaf evergreen group contained all pigments as well but actually showed a higher intensity of pigments than the deciduous.

I thought that was interesting because in my hypothesis I had stated I believed the pigments in the deciduous plants would show to be more intense than those in the broadleaf evergreens. Of the evergreen samples, the yucca seemed to contain only chlorophyll and showed little sign of any other pigment. It was hard to tell, but it may have also shown yellow pigments.

The bands of pigments from the broadleaf evergreen samples showed a higher intensity in their bands of pigments than the deciduous samples. From research and observation I concluded that this could be because I tested the deciduous samples during the autumn season. During that time of the year the pigments in a tree are breaking down, while during a tree’s growing season the chlorophyll is constantly being replaced because of the need for photosynthesis for food.

I would like to test the same samples of deciduous trees during the growing season to see if there is an increase in the pigment intensity.

Observing my specimens, I found some irregularities throughout my tests. Sample number one was from a deciduous plant and was significantly lower in intensity of pigment color bands than the rest of the deciduous tests. I observed that the specimen was quite diseased and could be the reason for the lack of pigment intensity.

Sample C, which is a broad leaf evergreen seemed to show no signs of any other pigments except for chlorophyll and maybe a possible yellow pigment. All the other broadleaf evergreen samples showed the presence of all pigments.

My results showed that the pigments chlorophyll, xanthophylls, carotenoids, and anthocyanins were present in both deciduous and evergreen plants, with the pigments in the broadleaf evergreens being more intense than the pigments in the deciduous plants.

To see Megans complete project go to chromatography experiments for science fair projects.