Match each type of chromatography with its definition. In this type of chromatography, solute molecules equilibrate between the mobile phase and the surface of the stationary phase.
A type of chromatography in which solute molecules penetrate voids in the stationary phase. In this type of chromatography, the largest solute molecules elute from the column first. Mobile-phase ions are attracted to stationary-phase ions in this type of chromatography. Equilibration of solute between the mobile phase and a liquid film stationary phase occurs in this type of chromatography. In this type of chromatography, specific groups are attached to the stationary phase to attract the solute.
The Correct Answer and Explanation is:
To match each type of chromatography with its definition, we need to understand the principles that underlie each method:
Correct Matching:
- Adsorption Chromatography
➝ In this type of chromatography, solute molecules equilibrate between the mobile phase and the surface of the stationary phase. - Size-Exclusion Chromatography
➝ A type of chromatography in which solute molecules penetrate voids in the stationary phase. In this type of chromatography, the largest solute molecules elute from the column first. - Ion-Exchange Chromatography
➝ Mobile-phase ions are attracted to stationary-phase ions in this type of chromatography. - Partition Chromatography (Gas-Liquid Chromatography)
➝ Equilibration of solute between the mobile phase and a liquid film stationary phase occurs in this type of chromatography. - Affinity Chromatography
➝ In this type of chromatography, specific groups are attached to the stationary phase to attract the solute.
Explanation (300+ words):
Chromatography is a powerful technique used in analytical chemistry to separate, identify, and purify the components of a mixture. Different types of chromatography are based on different principles of interaction between solute, mobile phase, and stationary phase.
Adsorption chromatography works on the principle that solute molecules adsorb onto the surface of a solid stationary phase (like silica or alumina) and also dissolve in the liquid mobile phase. The strength of adsorption determines the retention time.
Size-exclusion chromatography (also called gel filtration) separates molecules based on size. The stationary phase consists of porous beads. Large molecules cannot enter the pores and elute quickly, while smaller molecules penetrate the pores and take longer to travel through the column.
Ion-exchange chromatography relies on the electrostatic interaction between charged solute molecules and oppositely charged groups on the stationary phase. For example, in cation-exchange chromatography, negatively charged resin attracts and binds positively charged ions from the solution.
Partition chromatography, especially in gas-liquid chromatography (GLC), involves a liquid stationary phase coated on an inert solid support. The mobile phase (usually a gas) carries the sample through the column. Solutes distribute between the gas phase and the stationary liquid film based on their volatility and solubility.
Affinity chromatography is highly specific. It involves attaching a specific ligand (like an antibody, enzyme substrate, or receptor) to the stationary phase. The target molecule in the sample binds specifically to the ligand, while other molecules wash through. This method is often used in biochemistry for purifying proteins and nucleic acids.
Each method is tailored to exploit a unique chemical property—such as size, charge, polarity, or biological specificity—to achieve effective separation. Understanding the underlying mechanism is crucial in selecting the most suitable chromatography type for a given analytical task.