what is the basic physical principle that chromatography is based upon?
Differential adsorption/absorption of a material between a stationary phase and a mobile phase.
http://www.rpi.edu/dept/chem-eng/Biotech-Environ/CHROMO/chromintro.html
The basic physical principle that chromatography is based upon is the differential partitioning of components between a stationary phase and a mobile phase. In chromatography, a mixture is separated into its individual components based on their different affinities for the stationary and mobile phases. The stationary phase can be a solid (in column chromatography) or a liquid (in paper or thin-layer chromatography), while the mobile phase is typically a liquid or a gas. As the mobile phase moves through the stationary phase, the components of the mixture interact with both phases differently, leading to varying degrees of retention and separation.
The basic physical principle that chromatography is based upon is the differential partitioning or distribution of components between two phases – a stationary phase and a mobile phase. The stationary phase could be a solid (like paper or silica gel) or a liquid (like a thin layer on a plate), while the mobile phase is typically a liquid or a gas.
To understand this principle, let's consider a common example of paper chromatography. In this technique, a small sample mixture of different compounds is spotted onto a sheet of paper as a stationary phase. The mobile phase, usually a liquid solvent, is then allowed to move over the stationary phase by capillary action.
As the mobile phase travels, the different components of the sample mixture will interact differently with the stationary and mobile phases based on their chemical properties. Some components may have stronger interactions with the stationary phase and move more slowly, while others may have weaker interactions and move more quickly with the mobile phase. This results in the separation of the mixture into its individual components, as they travel different distances on the paper.
The separation is based on a combination of different physical forces such as adsorption, partitioning, and solubility. These forces determine how strongly each component interacts with the stationary phase and the mobile phase, ultimately leading to their differential migration and separation.
By analyzing the resulting separation pattern, scientists can identify and quantify the different components present in a mixture. This principle is the foundation of chromatographic techniques, which have widespread applications in various fields including chemistry, biology, pharmacy, and environmental analysis.