Two Common Adsorbents for Adsorption Chromatography
Let’s take a look at two common adsorbents for adsorption chromatography.
The polyamide adsorbent can be divided into nylon 6 (polycaprolactam) and nylon 66 (polyhexamethylene adipamide), which are hydrogen bond adsorption and semi-chemical adsorption. There are many amide groups in the polyamide molecule, and C=O on the polyamide forms hydrogen bonds with phenol groups, flavonoids, -OH or -COOH in the acid. The amino group in the amide group forms a hydrogen bond with a sulfhydryl group or a nitro group in the hydrazine or nitro compound.
Separation is caused by the difference in the structure of the separated substances or the difference in the number and position of the reactive groups in the same type of structural compound, which affects the ability of the polyamide to form hydrogen bonds.
Activated carbon is a non-polar adsorbent, so contrary to silica gel and alumina, it has strong affinity for non-polar substances and strong adsorption capacity for solutes in water. When the polarity of the solvent is lowered, the adsorption capacity of the activated carbon for the solute is also reduced. When the adsorption capacity of the adsorbent is constant, the polarity of the solute is stronger, and the polarity of the eluent is weaker.