Alumina for Column Chromatography

Overview

Alumina for column chromatography is called as Activated Alumina.

Activated Alumina or Aluminium Oxide is manufactured by dehydroxylating aluminium hydroxide which leads to the formation of a porous powder having high surface area.

Alumina is a polar column chromatography adsorbent and will give separations by polar interactions. Thus, the mobile phase used will be a non-polar solvent.

Silica Gel and Alumina are both polar adsorbents, but Silica Gel is less polar than Alumina.

Carbon-carbon double bonds contribute somewhat more to compound adsorption on alumina as compared to silica gel, and hence compounds with unsaturation are generally better separated on Alumina than on other polar adsorbents such as silica gel.

Alumina manufactured is of three types based on the pH ranges – acid, neutral and basic.

The separation order may change for basic, neutral and acidic alumina and hence they should be considered as distinct adsorbent subtypes and hence they are used for separation of different types of compounds.

Uses of Activated Alumina

• Activated alumina has high water adsorption capacity and hence it is used as a desiccant in many air or gas drying processes, dehydration of oil, etc.
  
• Neutral Alumina has a pH range of 6.0 – 7.5 and is useful for separation of aldehydes, ketones, quinones, esters, lactones, and glucosides
  
• Acidic Alumina has a pH range of 4.0 – 5.5 and is useful for separation of acid pigments, strong acids, phenols, sulfonic, carboxylic and amino acids.
  
• Basic Alumina has a pH range of 8.0 – 9.5 and is useful for the separation of basic and neutral compounds, as well as for alcohols, hydrocarbons, amines, imines and basic dyes.

Particle size (Mesh)

100-200 Mesh, 200-300 Mesh