Final answer:
In chromatography, the stationary phase consists of a solid or a liquid on a solid support, where components of a mixture are temporarily adsorbed. The mobile phase is the solvent that carries mixture components through the stationary phase, with separation based on differing affinities. In HPLC, solutes' hydrophobicity often predicts their affinity for the stationary phase, affecting the order they elute from the column.
Step-by-step explanation:
In paper chromatography, the stationary phase is generally composed of a solid material or a layer of a liquid adsorbed onto the surface of a solid support. The stationary phase in chromatography does not move and is the phase on which the components of the mixture get adsorbed temporarily. On the other hand, the mobile phase consists of the solvent that moves through or over the stationary phase, carrying the components of the mixture with it. The components of the mixture have different affinities towards the stationary and mobile phases, causing them to separate based on different partition coefficients and their overall ability to interact with the stationary phase.
When considering column chromatography, for example, the separation process involves solutes being introduced at the top of the column as part of the mobile phase. As the mobile phase travels through the column, components with higher affinities for the stationary phase will move slower compared to those with less affinity. This differential movement, often due to the differences in hydrophobicity or molecular size, allows for separation of the substances. Notably, reverse phase HPLC relies on a stationary phase often made of silica that has been treated to create a hydrophobic surface, thus causing hydrophobic solutes to take longer to elute.
To predict which of the five phosphatidylcholines will be most attracted to the stationary phase, one should consider the structure and hydrophobicity of each. The more hydrophobic the molecule is, the more likely it is to interact with the stationary phase and move more slowly through the column. Conversely, the less hydrophobic molecules are less attracted and hence will pass through the column more quickly, predicting their order of elution.