Chromatography of Pigments

Introduction

Paper chromatography is a method using a chromatography paper to identify the many mixtures of one simple color. The word chromatography comes from the Greek words, "chroma," meaning color, and "grafein," meaning to write. The process of this experiment is to place a colored dot, such as marker ink, onto the chromatography paper, one centimeter away from the triangular tip. Next dip your chromatography paper into the solvent, not allowing it to touch the colored dot. Let it sit for about 15 minutes to let the solvent rise upon the paper. During those 15 minutes, the solvent will meet with the colored dot, and will continue to travel, separating color by color. Different compounds will have different effects on the chromatography paper's distance, depending on the strength of the interaction with the paper. After 15 minutes you will be able to identify the colors. The purpose of this paper is to help analyze or compare pigments from two organisms. Chromatogram is the pattern that the chromatography paper has created from its substances. A retention factor, also abbreviated as an Rf value, is the measurement of the distance that the sample had traveled. The formula for an Rf value is migration distance of solvent front divided by migration distance of substance. An Rf value is the distance the pigment travels from the original spot, which is the dot, of solvent distance to the solvent front. Scientists use paper chromatography to identify the different pigments of a plant, and how many it contains.

Hypothesis

Paper chromatography can help scientists tell apart different plants, and compare and contrast the amount of pigments.

Materials

The materials you will need in order to perform this experiment is a chromatography jar, motar and pestle, spinach, chromatography paper, chromatography solvent, a ruler, a capillary tube, and a calculator.

Procedure

See lab sheet

Results

Data Table 1

Line Color Probable Pigment Distance from Start Rf Value

1 Bright Green Chlorophyll A 3mm 3mm

2 Faint Yellow Carotenes 1mm 4mm

3 Yellow-green Chlorophyll B 2mm 6mm

4 Yellow Xanthophylls 5mm 12 mm

1. How many pigments were found in the spinach leaf?

Four pigments were found in the spinach leaf.

2. Which of these pigments would be considered