Chromatography of Plant Pigments

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CHROMATOGRAPHY OF PLANT PIGMENTS
Marquez, Ma. Rica Paulene, Moises, Patrisha Kate, Policarpio, Jairus Paolo, Rolda, Zylene Joy Department of Biology, College of Science, University of the Philippines Baguio April 23, 2013

ABSTRACT
The objective of this experiment was to apply the technique of paper chromatography as a method for separating individual plant pigments contained in plant tissue extracts containing pigment blends. The process of chromatography separates molecules because of the different solubilities of the molecules in a selected solvent. In paper chromatography, paper marked with an unknown, such as plant extract, is placed in a beaker covered with a foil containing a specified solvents. The solvent carried the dissolved pigments as it moved up the paper. The pigments were carried at different rates because they were not equally soluble. The most soluble pigment traveled the longest distance while the others traveled in a shorter length. The distance of the pigment traveled was unique for that pigment in set conditions and was used to identify the pigment. The ratio was then used to measure the Rf (retention factor) value.|

INTRODUCTION
As primary producers in the food chain with some bacteria and algae, plants produce their own food by using the sun’s energy to transform carbon dioxide and water into glucose. In this process of photosynthesis, plants convert the sun’s energy into chemical energy that is stored in the bonds of the glucose molecule. Glucose is a simple carbohydrate that provides immediate fuel to cells but it is also a building block for more complex carbohydrates stored by living organisms for future use. For photosynthesis to transform light energy from the sun into chemical energy (bond energy) in plants, the pigment molecules absorb light to power the chemical reactions. Plant pigments are macromolecules produced by the plant, and these pigments absorb specified wavelengths of visible light to provide the energy required for photosynthesis. Chlorophyll is necessary for photosynthesis, but accessory pigments collect and transfer energy to chlorophyll. Although pigments absorb light, the wavelengths of light that are not absorbed by the plant pigments are reflected back to the eye. The reflected wavelengths are the colors we see in observing the plant.Plants contain different pigments, and some of the pigments observed include:  chlorophylls (greens)

 carotenoids (yellow, orange red)
 anthocyanins (red to blue, depending on pH)
 betalains (red or yellow)
(Plant Traveling Lab. TTU/HHMI at CISER. 2010)
As you may know from the popular media, there is currently a substantial research effort in place to explore the potential health benefits of plant pigments to humans. In popular literature, these plant-based compounds are often collectively referred to as “phytochemicals”; most are also pigments. Flavonoids, anthocyanins, and carotenoids are just some of the categories of plant pigments known to have antioxidant properties. “Antioxidant” is a general term used to describe any substance that has the ability to neutralize “free radicals” which cause cellular damage by removing electrons from surrounding molecules. Many lines of research suggest that consuming a diet rich in plant pigments may slow the process of cellular aging and reduce the risks of some types of disease, such as cancer, heart disease, and stroke. The point of this experiment is to look at the polarity of some of the common pigments in plant leaves and how that polarity affects their interactions with the cellulose fibers in paper and a few solvents and to apply the technique of paper chromatography as a method for separating individual plant pigments contained in plant tissue extracts containing pigment blends. (https://www.msu.edu)

RESULT
Table 1 shows the Rf values of Kangkong (Ipomoea aquatic), Bloodleaf (Iresine herbstii), and Golden bush (Duranta repens) plant| Rf value|
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