chlorophyll lab report

Alyssa Caparelli

Organic Chemistry 12A

Professor Alston

October 28, 2014

Isolation of Chlorophyll and Carotenoid Pigments from Spinach

Purpose

The purpose of this experiment was to isolate ß-carotene, chlorophyll-A, and chlorophyll-B from spinach using column chromatography. Spinach was dehydrated using ethanol, and the pigments were extracted with dichloromethane. The spinach extracts were dried using CaCl2. Then, the solid pigments were run through a column using a non-polar solvent, hexane. The polar absorbent material in the column separated the different pigments by allowing the least polar molecules to travel through the column faster than the more polar molecules. The different pigment layers were collected, dried, and their weights were recorded. ß-carotene was the least polar molecule, and it traveled through the column faster than the chlorophylls. Chlorophyll-A was next to travel through the column followed by chlorophyll-B. Because chlorophyll-A is more polar than ß-carotene and less polar than chlorophyll-B, this observation is reasonable.

Introduction

ß-carotene is a yellow-orange pigment found primarily in fruits and vegetables. ß-carotene is a carotenoid that is effective in preventing sunburn in sun-sensitive people, reducing the risk of breast cancer and other diseases, preventing asthma attacks caused by exercise, as well as many other uses. Chlorophyll is the green, light-capturing pigment found in plants. Chlorophyll (like heme in red blood cells) is an example of porphyrin. In this experiment, chlorophyll and ß-carotene were isolated using the technique of column chromatography.

Column chromatography is a method used to separate and purify components in a mixture. In gravity column chromatography (used in this experiment), a vertical glass column is packed with a polar absorbent and a solvent. Then the sample is allowed to pass through the column, which separates the different components.

In this experiment, pigment components were dehydrated and extracted from spinach,

and the extracts were passed through...