PAPER CHROMATOGRAPHY WORKING MODEL

Paper chromatography is a technique used to separate and analyze the components of a mixture based on their solubility and affinity for a mobile phase (solvent) and a stationary phase (paper). It is widely used in chemistry laboratories for qualitative and quantitative analysis of mixtures.

**Principle:**
The principle behind paper chromatography is the differential partitioning of the components of a mixture between a mobile phase (usually a liquid solvent) and a stationary phase (the paper). As the mobile phase moves through the paper via capillary action, it carries the mixture’s components along with it. However, each component interacts differently with the stationary phase and mobile phase, leading to separation based on differences in solubility and affinity.

**Procedure:**
1. **Preparing the Stationary Phase:** A piece of chromatography paper is cut into a rectangular strip and marked with a pencil line near one end to indicate the origin of the separation.

2. **Application of Sample:** A small amount of the mixture to be analyzed is applied to the origin line as a spot or line using a capillary tube or micropipette. It’s essential to apply the sample accurately and precisely to ensure reliable results.

3. **Development of Chromatogram:** The bottom edge of the paper strip is then immersed in a solvent or mobile phase contained in a suitable container (such as a beaker or chromatography tank). As the solvent moves up the paper via capillary action, it carries the sample components with it. Different components move at different rates, leading to their separation along the paper strip.

4. **Visualization:** Once the solvent front nears the top of the paper strip, the chromatogram is removed from the tank and allowed to dry. The separated components are visualized by using suitable detection methods, such as UV light, staining, or spraying with a visualization reagent.

**Factors Affecting Separation:**
– Choice of solvent: The selection of an appropriate solvent is crucial, as it determines the separation efficiency and resolution. The solvent should have suitable polarity and volatility.

– Paper type: The properties of the chromatography paper, such as thickness, porosity, and absorbency, influence the separation process. Different types of paper (e.g., filter paper, cellulose paper) may be used depending on the application.

– Sample application: The amount and concentration of the sample applied, as well as the method of application, affect the quality of separation. Overloading the sample or uneven application can lead to poor resolution.

**Applications:**
– Analysis of dyes in food, ink, and textiles.

– Separation of amino acids, sugars, and organic acids in biological samples.

– Identification of drugs and pharmaceutical compounds.

– Analysis of environmental pollutants in water and air samples.

Paper chromatography is a versatile and cost-effective technique widely used in various fields of science, including chemistry, biochemistry, environmental science, and forensics, for separation, identification, and quantification of chemical compounds in complex mixtures.

Safety Precautions:

• Conduct the experiment in a well-ventilated area.
• Handle solvents with care and follow safety guidelines.
• Avoid direct contact with the eyes, skin, or mouth while handling chemicals.

Paper chromatography is a versatile and powerful technique used in various fields such as chemistry, biology, and forensics for separating and analyzing complex mixtures of substances.