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Chromatography is often used for the analysis of the mixture of amino acids that is formed when proteins are broken down - VCE - SSCE Chemistry - Question 5 - 2003 - Paper 1
Question 5
Chromatography is often used for the analysis of the mixture of amino acids that is formed when proteins are broken down. The small protein enkephalin is known for i... show full transcript
Worked Solution & Example Answer:Chromatography is often used for the analysis of the mixture of amino acids that is formed when proteins are broken down - VCE - SSCE Chemistry - Question 5 - 2003 - Paper 1
Step 1
Explain how an Rf value is calculated.
Answer
The Rf value (retention factor) is calculated by taking the ratio of the distance traveled by the amino acid to the distance traveled by the solvent front. Mathematically, it can be expressed as:
In this context, the distance from the origin (initial spot) to the spot of methionine is measured, and then this value is divided by the distance from the origin to the solvent front. This ratio gives a relative measure of how far the amino acid has traveled compared to the solvent.
Step 2
Step 3
Describe how the sample containing the mixture of the four amino acids was added to the paper in order to begin the procedure.
Answer
The mixture of amino acids was applied to the chromatography paper using a capillary tube or a dropping pipette. A small drop was placed at the origin point (initial spot) to ensure proper application. Care was taken to prevent the sample from spreading out too much, maintaining a concentrated spot to achieve better separation during the chromatography process.
Step 4
What factors determine the different Rf values of the different amino acids?
Answer
The Rf values of the different amino acids are influenced by several factors:
- Polarity: Amino acids vary in their polarity, affecting their interaction with the stationary phase (paper) and the mobile phase (solvent).
- Solubility: The ability of the amino acids to dissolve in the mobile phase will affect how far they travel.
- Hydrogen bonding: Amino acids that are capable of forming hydrogen bonds with the stationary phase will have lower Rf values compared to those that do not.
These factors combined dictate the relative mobility of each amino acid during the chromatography process.