Chromatography Flashcards
What is chromatography???
Processes where separation of a mixture of substances can be achieved using the different degrees to which they undergo adsorption when passing over material of a different phase.
How does separation occur in chromatography???
A sample is placed on a solid which is the stationary phase.
Gas or liquid is passed through the system which is the mobile phase and the components will start to move by a process called elution.
How does separation occur in chromatography???
A sample is placed on a solid which is the stationary phase.
Gas or liquid is passed through the system which is the mobile phase and the components will start to move by a process called elution.
What is sorption???
The process where by solutes are transferred from mobile to stationary phase.
What is desorption???
The process where by solutes are transferred from stationary to mobile phase.
What are the four main sorption mechanisms???
Adsorption
Partition
Particle exchange
Size exclusion
Why does adsorption occur???
Because of electrostatic interactions between a compound and a surface of a stationary phase.
What is partition???
Where the stationary phase is liquid coated onto a solid.
Applies to bonded phases.
What is ion exchange???
Solute ions in the mobile phase can exchange with similarly charged ions bound to the stationary phase.
Can be used to separate and determine ions in water e.g. sulphate, chloride, fluoride.
What is exclusion???
Differs from the above 3 because there are no specific interactions between solute and stationary phase.
What are the ways of assessing accurate chromatographical data???
The peaks should be sharp and should not overlap.
