Question

Separating techniques such as gas chromatography and liquid chromatography are not appropriate for separation of amino acids. Select correct reason from the following 

• A. Amino acids high polarity substances
• B. Amino acids are low polarity substances
• C. Amino acids are non polar substances
• D. Amino acids lowly charges substances

Answer 1

The Correct Option is A

The question is about selecting the correct reason for the inappropriateness of using gas chromatography and liquid chromatography to separate amino acids. Understanding the properties of amino acids and the working principle of these chromatographic techniques will help in solving the question.

1. **Understanding Amino Acids:** Amino acids are organic compounds that serve as the building blocks for proteins. They contain an amino group (NH_2), a carboxyl group (COOH), and a variable side chain. Typically, they have significant polarity due to the presence of both acidic and basic functional groups.

2. **Gas Chromatography:** This technique is effective for volatile substances. However, amino acids are not volatile without derivatization, making gas chromatography unsuitable for their separation.

3. **Liquid Chromatography:** Liquid chromatography is used to separate compounds based on polarity, ionic interaction, or molecular size. While it can be adapted for amino acids, polarity can be a concern without proper derivatization and choice of stationary phase.

4. **High Polarity of Amino Acids:** Amino acids are high polarity substances due to their zwitterionic nature, which means they exist predominantly in a dipolar ion form at physiological pH. This high polarity makes their separation challenging using some conventional chromatographic procedures without derivatization.

5. **Evaluating Options:**

• **Option 1:** Amino acids high polarity substances - This option is correct. Amino acids' high polarity makes it difficult for direct separation using gas and conventional liquid chromatographic methods without modifications.
• **Option 2:** Amino acids are low polarity substances - Incorrect, as amino acids possess high polarity.
• **Option 3:** Amino acids are non-polar substances - Incorrect, amino acids contain polar functional groups making them highly polar, not non-polar.
• **Option 4:** Amino acids lowly charged substances - Incorrect, as amino acids can strongly interact with stationary phases depending on their ionizable groups' state.

The correct explanation is that amino acids are high polarity substances, which complicates their separation using techniques like gas chromatography and liquid chromatography without special preparation or columns.