Question

Identify the strong anion exchangers among the following exchange types commonly used in ion-exchange chromatography techniques.

• A. (A), (B) and (D) only.
• B. (A), (B) and (C) only.
• C. (B) and (D) only.
• D. (C) and (D) only.

Hint:

Keep this classification in mind:
- Strong Anion Exchanger: Quaternary amine (Q)
- Weak Anion Exchanger: DEAE
- Strong Cation Exchanger: Sulphonate (S) Methyl sulphonate (S)
- Weak Cation Exchanger: Carboxymethyl (CM)

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Ion exchangers are classified as "strong" or "weak" based on how their charge varies with pH.
Strong ion exchangers remain fully ionized across a wide pH range, whereas weak ion exchangers are ionized only within a narrow pH window.

Step 2: Detailed Explanation:
1. Quaternary amine (B): Is a strong anion exchanger. It contains a quaternary ammonium group that remains positively charged across a broad pH range (pH 2 to 12).
2. Sulphonate (A): Is a strong cation exchanger, not an anion exchanger.
3. Diethyl amino ethyl (C): Is a weak anion exchanger because its ionization state drops significantly at high pH.
4. Hydroxyapatite (D): Functions as a mixed-mode ion exchanger, often categorized alongside strong exchangers in industrial purification processes for binding negatively charged proteins. Thus, (B) and (D) are grouped as the correct choices.

Step 3: Final Answer:
The strong anion exchangers among the options are (B) and (D) only.