Chromotography

• What is chromatography?

  A technique used to separate and analyse the components of a mixture based on their different interactions with a stationary phase and a mobile phase. It is used to identify and quantify the compounds present in a sample.
• What is a stationary phase?

  A stationary phase is a solid or liquid material that is used in chromatography to separate and analyze different components of a mixture.
• What is a mobile phase?

  The solvent that moves through the stationary phase.
• Depending on their intermolecular forces, the components will be more attracted to either the mobile or stationary phase.
• Define Affinity?

  Components of a sample are attracted by intermolecular forces, to the mobile or stationary phase. High affinity means that the component interacts strongly with the mobile or stationary phase.
• What is adsorption?

  Components of the sample absorb onto the stationary phase from the mobile phase if they are attracted to, or have an affinity for, the stationary phase.
• What is desorption?

  Components of the sample desorb off the stationary phase into the mobile phase if they are attracted to or have an affinity for the mobile phase.
• What is the 'like with like' rule?

  Atoms, molecules, and ions are more attracted to a mobile or stationary phase that has the same or similar properties.
• Describe paper chromatography.

  The stationary phase is a thin strop of absorbent paper, this fits in a container holding the mobile phase. The origin line on the paper shows the start of the sample and standards. The mobile phase is added so it sits below the origin and the sample then travels up the paper, in its different components.
• What is thin layer chromatography?

  Works the same as paper chromatography with a glass or plastic support is coated in a thin layer of the stationary phase, for example silica gel.
• What is column chromatography?

  A glass column is filled with a stationary phase, the mobile phase is poured into the top of the column until the column is soaked. The sample is added in the top and the bottom is opened. The sample separates into its various components.
• What is gas chromatography?

  The mobile phase is an inert gas. A solid or liquid stationary phase is used and the sample separates as each component interacts with the stationary phase.
• What is high performance liquid chromatography?

  The mobile phase is liquid which is pumped through an instrument. A solid stationary phase is used and the sample separates as each component interacts with both the mobile and stationary phase.
• What is retention time (Rt)?

  The time it takes a sample to move through the column from injection to detection.