Analysis of Plant Pigment

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  • Topic: Chromatography, High performance liquid chromatography, Silica gel
  • Pages : 4 (1096 words )
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  • Published : April 1, 2013
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Experiment 5

Analysis of Plant Pigment

Purpose: Chromatography is used for separation. In this case the separation of plant pigments. After placing the plant sample in the column the separation will be easy to see and the samples will be analyzed using VIS spectrophotometry. This is used to isolate and identify the different lipids causing the different pigmentations.

Introduction: Lipids are chemically diverse substances found in cells. Lipids are water-insoluble, structural components of membranes, store metabolic fuel and are protective components of membranes and skin. Plant pigments have “lipid-like” properties and typical pigments found in plants are chlorophyll A, chlorophyll B, β-Carotene, lutein, neoxathin, violaxanthin, and phaeophtin. The most abundant of the pigments are chlorophyll A and chlorophyll B, the only

Name of Class fast alkanes alkenes ethers halogenated hydrocarbons aromatic hydrocarbons increasing polarity aldehydes and ketones esters alcohols amines slow carboxylic acids

General Formula

difference between the

two is that on ring 3 chlorophyll a has a RH R2C CR2 methyl group where chlorophyll b R2O RX CH3 has an aldehyde functional

, etc

group. None of these

main pigments absorb green

RCH O and R2C O light, which is why O RCOR ROH pigments present in RNH 2 , R 2NH, R 3 N O

plants look green to the human eye. The

spinach are chlorophyll a, chlorophyll b,

RCOH carotene, pheophytins and xanthophylls.

Figure 1: Chart of how molecules with higher polarity elute faster through the column.

Separation of lipids can be accomplished through Column Chromatography (CC) or High Performance Liquid Chromatography (HPLC). Both of these separation techniques are known as absorption chromatography. The column can be packed with alumina, activated charcoal, magnesium silicate, silica gel, inorganic carbonates, starch, cellulose, or sucrose, and the more polar the molecule the higher up the list you would...
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