Chromatography Using Spinach Extract

Organic Chemistry 1 Laboratory

CH2720

Lab Report 1: Chromatography Using Spinach Extract

Name: Kim Le

Date: September 6, 2011

Partner: Phu Bui

Purpose/Goal/Objective:

The purpose of this lab was using the techniques in liquid chromatography and TLC (Thin Layer Chromatography) to be able to separate the colored compounds in the spinach extract. In this case, the colored compounds were chlorophyll, carotenoids, and xanthophyll. The goal of this experiment is observe which solvents dissolve which. The saying is “like dissolves like” so we will observe that polar solvent dissolves polar substances and likewise, non-polar solvents dissolve non-polar substances. The objective of this experiment is to observe how liquid chromatography works as well as how TLC works.

Background:

Figure a: Pheophytin

Figure b: Chlorophyll

Figure c: Xanthophyll

Figure d: Carotene

The structure of the carotenes are more nonpolar than that of the xanthophyll. As observed, all compounds have alternating double and single bonds. This is called conjugation, where the compounds go from UV light to visible light. The polar compounds can only be dissolved by polar solvents whereas the nonpolar compounds can only be dissolved by the nonpolar solvents.

Procedure:

A water bath was prepared for the substances to be boiled later. Fresh spinach was prepared for the class. To prepare the extract, fill the blender ¾ full with spinach leaves and as 10 mL of water, 3 tbsp. of salt and 100 mL of 75/35 hexanes2 / acetone mixture. Puree the leaves and pour the mixture into a beaker. Now, pour this into a test tube to be centrifuged for one minute. Once the tube was centrifuged, the extract layer was moved to another test tube to be boiled until the extract was more condensed. A column was prepared by first adding a bit of glass wool, then a bit of sand and finally 5.7 cm of silica gel. Hexane was added to the column to soak the silica gel, sand and wool in the column. Then 8 drops...