Lab 6ss01-713633818

Lab 6ss01-713633818 - Experiment 6: The Extraction of Plant...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Experiment 6: The Extraction of Plant Pigments from Spinach and the Subsequent Separation and Analysis of the Extracted Pigments Using Liquid Chromatography Neel Parikh June 4, 2008 Lab Partner: Andrew Nguyen TA: Meredith Turner Section 403 Morehead 400 Pledge: __________________________________
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Introduction: The purpose of this experiment is to extract pigments from a spinach extract using reverse-phase liquid chromatography by gradient elution. The goal of this experiment is to become familiar with the concept of liquid chromatography and how it can be used to analyze plant pigments and to understand the factors involved in analyzing these complex mixtures. The second goal is to understand the effects of pH changes on pigments. Plant pigments can be classified into three major groups: porphyrins, carotenoids, and flavenoids. Porphyrins include chlorophyll a, which displays a green color, and chlorophyll b, which exhibits a yellow-green color. These are usually the colors of the leaves seen during the spring and summer. The carotenoids include the carotenes and xanthophylls. Examples of carotenes are α, β, and λ carotene (yellow-orange) as well as lycopenes (red). The xanthophylls include lutein, zeaxanthin, violaxanthin, and newxanthin (yellow). Theses leaf colors show in the fall. The last group, the flavenoids, include flavone (yellow), flavonol (yellow), and anthocyanin (red, blue, purple). These pigments produce the colors of leaves and flowers. The pH of a solution containing plant pigments can be changed, which changes pigment structures and pigment colors as well. For example, changing the pH of a solution containing anthocyanin from pH 3.00 to pH 7.00 or pH 8.00 will change to color from red to violet. Increasing the pH to pH 11.00 will change the violet to blue. Therefore, the color of the pigment solution is a good indicator of the pH. Before analysis of a pigment can occur, the plant cells must be broken up. In this experiment, a blender was used to expose the plant pigments. These desired pigments were then extracted using solvent-solvent extraction. Solvent-solvent extraction takes advantage of the different solubilities. Depending on a solute’s properties, it will be attracted to either the organic
Background image of page 2
phase or the aqueous phase. In this lab, the flavonoids and trihydroxy derivative xanthophylls are retained in the aqueous phase while the chlorophylls, carotenes, and derivative xanthophylls are retained in the organic phase. These pigments in the organic phase are then separated further in a chromatograph by using their difference in polarities. In a liquid chromatography (LC) column, the mobile phase is passed through the column that separates the pigments. When these pigments are passed through a column, they produce different colored bands. Two techniques can be used in LC. The first is called normal-phase LC, in which the stationary phase is polar and the mobile phase is nonpolar. In this normal-phase LC, nonpolar solutes elute first from the column. Polar solvents are attracted to the polar stationary
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 12

Lab 6ss01-713633818 - Experiment 6: The Extraction of Plant...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online