All living organisms call for power for their metabolic (chemical) processes. The ultimate source of this energy is the sun. Photosynthetic organisms, including plants, protists (single-celled organisms), and also blue-green algae (cyanobacteria), convert light energy right into the chemical power of sugars, which deserve to be used to power metabolism. During photosynthesis, molecules referred to as pigments (as a result of the wavelength, thus color, they reflect) are offered to capture light energy. Four major pigments of green plants deserve to conveniently be separated and also identified making use of a method called paper chromatography. These pigments incorporate two greenish pigments called chlorophylls and also 2 yellowish pigments called carotenoids. Pigments are separated according to distinctions in their relative solubilities.
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In order to extract these pigments from the thylakoid membranes of the chloroplasts, the organelles in which photosynthesis occurs, fresh, ground or torn leaves (preferably spinach) may be soaked in acetone or focused alcohol. The chloroplast pigment extract pictured at left was derived by boiling fresh leaves of spinach in 95% ethanol for a number of minutes and also then filtering utilizing gravity filtration. Pigments are then "painted" onto strips of chromatography paper with V-shaped tips using a tiny, hollow glass tube or a small paintbrush. For finest results, enable the line of pigments to dry, then repeat the process until a dark green line of pigments is evident (around six times is adequate to attain a dark pigment line).
Next off, chromatography solvent is offered to separate the mixture of pigments painted on the paper. In the experiment pictured at left, the solvent offered was comprised of nine components petroleum ether and also one component acetone. A small amount of this solvent is added to a large test tube and capped via a rubber stopper. Keep in mind that chromatography solvent is extremely volatile and also flammable. The V-shaped reminder of the paper is inserted in the chromatography solvent and acts as a wick to attract the solvent up the paper, separating pigments according to their relative solubility and also molecular weights. The paper is allowed to reprimary in the solvent till the uppermost pigment band also nears the peak of the paper.
A second experiment using the chloroplast pigment extract acquired utilizing the methods described above deserve to be quickly done. Green-colored pigment extract is included right into a test tube. When a light is shone on the extract, pigment molecules absorb power. Due to the fact that the pigments have been isolated from the thylakoid membranes of the chloroplasts, the power cannot be supplied for photosynthesis.
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Instead, the power is released as warmth and light in a procedure referred to as fluorescence. The pigments flouresce at a reduced energy level than what they absorb, so the chlorophylls flouresce a red color (red has actually the lowest amount of power of any type of of the colors in the visible spectrum). Flourescence of the pigment extract is presented in the photo.