GATE BT 2024 • Q11
MCQ • 1 Mark
Section 4: Bioprocess Engineering and Process Biotechnology
Bioreactor types, scale-up
Subtopic: Fundamentals of Bioreactor types, scale-up
Question Statement:
In adsorption chromatography, the adsorption of uncharged solute molecules onto
a silica-based stationary phase is by ________.
Options:
-
(A) covalent bonds
-
(B) electrostatic interactions
-
(C) ionic bonds
-
(D) van der Waals forces
Step-by-Step Solution & Explanation
### **Official Solution & Concept Analysis (GATE BT 2024 Q.11)**
**1. Governing Concept**:
- **Topic**: Downstream Processing & Adsorption Chromatography
- In normal-phase and non-ionic adsorption chromatography using silica-based matrices, uncharged non-polar/moderately polar solutes adsorb onto the surface through non-covalent, non-electrostatic intermolecular forces, primarily **van der Waals forces** (dispersion and dipole-induced dipole interactions) and weak hydrogen bonds.
**2. Option Analysis**:
- **Option (A) [covalent bonds] is INCORRECT**: Covalent bonding represents chemisorption, which is irreversible under normal chromatographic elution conditions.
- **Option (B) [electrostatic interactions] is INCORRECT**: Electrostatic interactions govern ion-exchange chromatography involving charged solutes and ionic ligands.
- **Option (C) [ionic bonds] is INCORRECT**: The solute molecules are explicitly uncharged.
- **Option (D) [van der Waals forces] is CORRECT**: Reversible physical adsorption of uncharged molecules onto stationary phases is driven by van der Waals forces.
**3. Final Answer**:
- **Correct Choice**: **D**
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