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An example is the spinach leaf, which appears dark green, but is actually a mixture of several pigments of different color. In order to identify the individual pigments, chemists use a technique known as chromatography (‘chroma’ refers to color) to separate out the different pigments.
Paper chromatography separates compounds on paper as solvent carries the mixture up (or down) the paper by capillary action. Compounds which are very soluble in the solvent move along with the advancing solvent front, while less soluble compounds travel slowly through the paper, well behind the solvent front.
In this column chromatography experiment, you will separate the pigments from the spinach. An aliquot experiment of the extracted spinach will be applied to an silica column.
Column chromatography will be used to separate the pigments present in spinach leaves, namely the green chlorophylls, orange carotenes and yellow xanthophylls. The pigments will be isolated from the leaves by solvent extraction and then separated by the two types of chromatography.
Students use thin-layer chromatography to separate the various pigments that are present in two different leaf extracts. They identify each pigment and determine whether the two extracts have any pigments in common. The experiment is suitable for students aged 11–16 and takes 1–2 hours to complete.
Plant Pigment Chromatography. Students will isolate and identify photosynthetic pigments in spinach leaves. Students will calculate Rf values of photosynthetic pigments and graph the absorption spectrum for each pigment.
28 wrz 2021 · How Leaf Chromatography Works. Paper chromatography separates pigments in leaf cells on the basis of three criteria: Solubility; Molecule size; Polarity; Solubility is a measure of how well a pigment molecule dissolves in the solvent. In this project, the solvent is alcohol. Crushing the leaves breaks open cells so pigments interact with alcohol.
