Chromatography of amino acids
Q. Which solvent gave the best separation of the pigments?
It is necessary that the solvent is slightly polar so that the substances to be separated will not completely mix with the solvent. The best solvent ratio is 30 hexane:70 ethyl acetate.
Table of Contents
- Q. Which solvent gave the best separation of the pigments?
- Q. What would the result be if the spots are too concentrated in a TLC experiment?
- Q. Why is the RF value less than 1?
- Q. Which two pigments migrated furthest from the solvent front and why?
- Q. What factors affect the separation of the pigments?
- Q. What did the different colored bands signify in each solvent for Part 1 What pigments can you associate them with?
Q. What would the result be if the spots are too concentrated in a TLC experiment?
Streaking: If the sample spot is too concentrated, the substance will travel up the stationary phase as a streak rather than a single separated spot. In other words, the solvent can not handle the concentrated sample and in result, moves as much of the substance as it can up the stationary phase.
| Amino acid | Rf value |
|---|---|
| isoleucine | 0.72 |
| leucine | 0.73 |
| lysine | 0.14 |
| methionine | 0.55 |
Q. Why is the RF value less than 1?
Rf is a fraction. It is the ratio of how far a substance travels up the chromatography paper compared to the distance the solvent has travelled. This means that it must be less than 1.
Q. Which two pigments migrated furthest from the solvent front and why?
Why? The pigment that traveled the furthest was carotene xanthophyll because it was the most soluble in the solvent. Chlorophyll b traveled least because it was the least soluble in the solvent.
Q. What factors affect the separation of the pigments?
What factors are involved in the separation of the pigments? The solubility, size of particles, and their attractiveness to the paper are all involved in the separation.
Q. What did the different colored bands signify in each solvent for Part 1 What pigments can you associate them with?
Different colored bands in each solvent signify the different materials that are found in the substance that is been analysed. The green band in the solvent represent the green chlorophyll which are found in leaves.
