Question

Which type of mechanism is applicable to chromatography?

(a) Absorption and Desorption

(b) Adsorption and Absorption

(c) Adsorption and Desorption

(d) Adsorption and Diffusion

I have been asked this question in exam.

The question is from Chromatography topic in portion Unit Operations of Bioprocess Engineering

Answer 1

Right option is (c) Adsorption and Desorption

For explanation I would say: Adsorption means the attraction to a substance (as opposed to absorption, which means the complete envelopment of something). Desorption is the opposite – when something is not attracted to the substance. How it relates to chromatography is through the mobile and stationary phase. Depending on what the substance adsorbs or desorbs to, will determine how it will move in the chromatogram. For example, if it adsorbs to the mobile phase, it will move a lot. However, if it adsorbs to the stationary phase, it will not move very much. This is how mixtures are separated through chromatography, as different substances in the mixture will adsorb and desorb differently, and hence will move differently, and thus separation is achieved.