Question

In reverse phase chromatography, the stationary phase is made:
(A) Non-polar
(B) Polar
(C) Either polar or nonpolar
(D) None of the above

Answer 1

Hint: In reverse phase chromatography, the polarity of the phases is inverted as compared to the normal phase chromatography. In reverse phase chromatography, silica cannot be used as a stationary phase.

Complete step by step solution:In a broad sense, chromatography can be divided into two categories depending upon the phase system, normal phase chromatography and reverse-phase chromatography.
- We know that chromatography is a technique to separate the solute components from a mixture.
- We use two phases to separate the solutes of the mixture. The names of the phases are the mobile phase and a stationary phase.
- Mobile phase is a phase which is not stationary and it moves through the stationary phase. The stationary phase is a phase which generally does not move and a mobile phase is passed through it.
- In reverse phase chromatography, the stationary phase is a non-polar compound and mobile phase is a polar compound.
- So, a non-polar stationary phase has more affinity towards the non-polar solutes and polar mobile phase has more affinity towards polar solute molecules.
- Thus, we can say that as we pour the mobile phase, the solutes will interact with both the stationary phase and mobile phase. Depending upon the nature of the solute, it will have a slow or fast speed of movement along with the flow.
- If the solute is polar, then it will move faster as the mobile phase is also polar and if the solute is non-polar, then it will move slower as the stationary phase is nonpolar.
- Thus, we can say that in reverse phase chromatography, the stationary phase is non-polar.

Therefore, the correct answer is (A).

Note: Do not get confused between the polarity of phases in normal phase and reverse phase chromatography. In normal phase chromatography, the stationary phase is polar and the mobile phase is non-polar. The phases are inverted in reverse phase chromatography.