Paper Chromatography
Chromatography
Abstract
Paper chromatography is one of the methods under chromatography, it can use in identifying unknown compounds using known compound and it can also use as a separation technique based on the differences in affinities of components of the mixture to a stationary phase and a mobile phase. In the experiment, the stationary phase was the filter paper onto which the dye samples were dropped onto while the mobile phase was the solvent mixture containing ethanol and water which carried the sample dyes as the mixture went up the paper at different rates. These rates depend on the solubility and polarity of compounds in solvent. The objectives of this experiment are to compute the retention factor values of 6 sample dyes: methyl …show more content…
It is a simple yet effective technique for determining the purity of compounds and identifying substances. Moreover, it can also separate impurities from pure compounds. Paper chromatography is useful technique since it is relatively quick and consumes fewer amounts of materials.
Like any chromatography, it involves two phases; stationary phase (a liquid or a gas) and the mobile phase (a solid, or a liquid supported on a solid). In paper chromatography, the stationary phase is the chromatogram paper while the mobile phase is the solvent which travels to the stationary phase and carries the components with it, like ethanol. Due to the capillary action, the liquid is able to move up the filter paper because its attraction to itself is stronger than the force of gravity.
Different components travel with different rates. These rates depend on the solubility and polarity of the components of the mixture. Differences in solubility of components are due to the difference in sizes, shapes of molecules and polarity. A component which is quite soluble in the stationary phase will take longer to travel through it than a component which is not very soluble in the stationary phase but very soluble in the mobile …show more content…
How is Rf related to the polarity of a compound? Which type of compounds will have greater Rf values?
Polar compounds passed through the column stick longer to the polar silica while non-polar compounds spend longer time with the non-polar mobile phase. The more polar the higher the rf values.
2. Explain the importance of the following precautions in doing paper chromatography
a. The paper must be handled only at the edges
Handle the paper only the edges of paper or use clean gloves to avoid contamination and leaving fingerprints because oils from hands can affect the separation.
b. The chromatography chamber must be tightly recovered.
It is necessary to close the chromatography chamber tightly so that the atmosphere within the chamber becomes saturated with solvent vapor.
c. The edges of the paper must not touch each other during the development of the chromatogram.
The edges of paper should be 2-2.5 mm away from each other because if the edge overlap and touch, it will affect the flow of the solvent at that point.
d. The sample spots must be above the solvent level in the chromatography chamber.
If the level of the solvent is higher than the sample spots, the sample spots will be washed off before it travels into the chromatography
Abstract
Paper chromatography is one of the methods under chromatography, it can use in identifying unknown compounds using known compound and it can also use as a separation technique based on the differences in affinities of components of the mixture to a stationary phase and a mobile phase. In the experiment, the stationary phase was the filter paper onto which the dye samples were dropped onto while the mobile phase was the solvent mixture containing ethanol and water which carried the sample dyes as the mixture went up the paper at different rates. These rates depend on the solubility and polarity of compounds in solvent. The objectives of this experiment are to compute the retention factor values of 6 sample dyes: methyl …show more content…
It is a simple yet effective technique for determining the purity of compounds and identifying substances. Moreover, it can also separate impurities from pure compounds. Paper chromatography is useful technique since it is relatively quick and consumes fewer amounts of materials.
Like any chromatography, it involves two phases; stationary phase (a liquid or a gas) and the mobile phase (a solid, or a liquid supported on a solid). In paper chromatography, the stationary phase is the chromatogram paper while the mobile phase is the solvent which travels to the stationary phase and carries the components with it, like ethanol. Due to the capillary action, the liquid is able to move up the filter paper because its attraction to itself is stronger than the force of gravity.
Different components travel with different rates. These rates depend on the solubility and polarity of the components of the mixture. Differences in solubility of components are due to the difference in sizes, shapes of molecules and polarity. A component which is quite soluble in the stationary phase will take longer to travel through it than a component which is not very soluble in the stationary phase but very soluble in the mobile …show more content…
How is Rf related to the polarity of a compound? Which type of compounds will have greater Rf values?
Polar compounds passed through the column stick longer to the polar silica while non-polar compounds spend longer time with the non-polar mobile phase. The more polar the higher the rf values.
2. Explain the importance of the following precautions in doing paper chromatography
a. The paper must be handled only at the edges
Handle the paper only the edges of paper or use clean gloves to avoid contamination and leaving fingerprints because oils from hands can affect the separation.
b. The chromatography chamber must be tightly recovered.
It is necessary to close the chromatography chamber tightly so that the atmosphere within the chamber becomes saturated with solvent vapor.
c. The edges of the paper must not touch each other during the development of the chromatogram.
The edges of paper should be 2-2.5 mm away from each other because if the edge overlap and touch, it will affect the flow of the solvent at that point.
d. The sample spots must be above the solvent level in the chromatography chamber.
If the level of the solvent is higher than the sample spots, the sample spots will be washed off before it travels into the chromatography