What is paper chromatography

Paper chromatography is an analytical technique used to separate mixtures into constituent components.

Paper chromatography principle: It consists of three components – stationary phase, mobile phase and the mixture to be separated. The mixture is allowed to move on the stationary phase using the mobile phase due to capillary action. Due to differential interaction of the different components of the mixture with the stationary phase, they move at different speeds and thus, get separated.

Steps followed in this paper chromatography experiment have been listed below:

• Take a filter paper strip (stationary phase) of 10 cm and make marks on both ends.

• Put a drop of the blue ink (analyte) using glass capillary or splinter near one of the marks on the filter paper strip.

• Take some tap water (mobile phase) in a test tube.

• Put the chromatography strip in the test tube. Make sure that the sample spot is above the water level.

• Wait till the water along with the sample reaches the top marking. Remove the strip from test tube to view the results.

Different components of blue fountain ink are now separated. Filter paper strip is made of cellulose, which is a polymer of glucose, which in turn consists of many polar groups. The analyte we used has different components which have different polarities and thus they interact differently with the stationary phase. Due to this difference in polarities, individual components of the analyte move up the filter paper, along with water, at different speeds. More polar the compound, stronger is the interaction with the stationary phase and hence slower is its speed. On the contrary, less polar the compound, weaker is its interaction with the stationary phase and hence faster the movement along the filter paper.

Paper chromatography applications: Paper chromatography has a wide range of applications such as in separation of amino acids, biochemicals in urine and also for determination of hormones, drugs etc. in the pharma sector.