Friday, October 30, 2015

Know Your Chromatography Adsorbents Better

We all know an adsorbent as a highly porous material with a large surface area, which is capable of adsorbing substances by using inter molecular forces. Adsorbents find extensive use in thin-layer and column chromatography because of the fact that by using them, solutes are evenly distributed between the adsorbent surface and a mobile phase. Adsorbents find extensive use in gas-solid and liquid-soild chromatography. They are also utilized to extract traces of organic materials from large amounts of water. The most commonly used adsorbents in both gas-soild and liquid-solid chromatography include silica gel, alumina, carbon and different types of bonded phases. 

Where are Adsorbents Mostly Used?

Supplier of Chromatography Adsorbents
The type of adsorbent to be used in chromatography, be it thin-layer, flash or column, depends on the nature of the mixture that has to be split apart. One also needs to factor in the purpose for which the chromatography is being carried out. Chromatography adsorbents are mainly used in research laboratories across the world as here many compounds are joined together and then separated to produce expensive drugs and other products. These adsorbents also find use in pharmaceutical and chemical companies, where chromatography is carried out on a regular basis to make pure products. 

Common Chromatography Adsorbents

1) Silica Gel: Silica Gel is one of the most commonly used chromatography adsorbents. These are very popular because of their high capacity for linear as well as non-linear iso-thermal separations. Silica gel adsorbents also display inertness for labile compounds, thus qualifying as the first choice for all forms of chromatography.  

Mainly a polar absorbent, silica gel is slightly acidic and therefore graviates towards adsorption of highly basic substances when compared to adsorption on a neutral or basic adsorbent. Silica gel mostly finds use in the separation of steroids, lipids, amino acids, dyes, alkaloids, phenolic compound and pharmaceutical intermediates. Most chemical companies are adsorbent suppliers for chromatography purposes as they offer adsorbents in various grades and pore sizes at highly affordable prices. 

2) Aluminium Oxide: After silica gel, aluminium oxide is the most preferred chromatography adsorbent. An all-purpose adsorbent, aluminium oxide is a typical polar adsorbent and separates matter almost in the same manner as silica gel. As alumina offers preferential adsorption of acidic substances, it is extensively used in the seperation of weak acids. Aluminium oxide is further helped by basic solvents. Aluminium oxide finds use mainly in separating dyes, dye intermediates, steroids, lipids, amino acids, hormones, alkaloids, aliphatic and aromatic hydrocarbons and other pharmaceutical products. Aluminium oxide is usually available in the powdered form in air-tight, humidity free packets. 

Other chromatography adsorbents like carbon, magnesium oxide and carbonates also find use in different types of chromatography. 

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