Using chromatography to identify amino acids

Identification of amino acids

Introduction

• Chromatography is a laboratory technique used to separate and analyse mixtures of compounds based on their properties.
• In the context of biochemistry, chromatography can be used to identify and analyse amino acids, the building blocks of proteins.

Chromatography Setup

• To perform chromatography for amino acid identification, you will need a chromatography paper strip, a solvent (usually a mixture of chemicals), and a sample containing amino acids.
• The paper strip is a long, narrow piece of special paper designed for chromatography. It acts as the stationary phase.
• A small amount of the amino acid sample is applied to the paper strip near one end, usually as a small spot or line.

The Process

1. Developing the Chromatogram: The paper strip is then placed vertically in a container with the solvent in the bottom. The solvent travels up the paper by capillary action, carrying the amino acids with it.

2. Separation of Amino Acids: As the solvent moves up the paper, it carries the amino acids at different rates. The rate of movement depends on the amino acid's affinity for the paper and the solvent.

3. Visualising the Results: When the solvent front nears the top of the paper strip, the strip is removed from the container. Amino acids are now separated along the strip based on their properties.

• Staining: To make the amino acids visible, a suitable staining method is used. Common stains include ninhydrin or iodine vapour.

Interpreting the Results

• Each amino acid will have moved a specific distance up the paper strip, forming distinct spots or bands.
• The distance each amino acid travels is known as the Rf (retention factor) value and is unique for each amino acid.
• By comparing the Rf values of the separated amino acids with those of known standards, you can identify the amino acids present in the sample.

---

Using chromatography to identify amino acids

Conclusion:

• Chromatography is a powerful technique for identifying amino acids in a mixture.
• It relies on the principle that different amino acids have varying affinities for the stationary phase (paper) and the mobile phase (solvent).
• By comparing the Rf values of separated amino acids with known standards, scientists can accurately identify the amino acids present in a sample, aiding in various biochemical analyses and research.