Chromotography Flashcards
What is Adsorption?
Adsorption is the binding of molecules to a surface or ‘Stationary Phase’
What is Chromotography
The process of finding compounds within a solution.
What does Rf stand for and mean?
Retention Factor - The distance of the component (solute) moved divided by the solvent. Rf is always less than one.
Rf= D(Solute)
———–
D(Solvent)
What is TLC and how is it better than paper chromatography?
Thin Layer Chromatography uses glass or aluminium instead of cellulose paper for a ‘Stationary Phase’. The advantages are that it is faster and more corrosive solvents can be used than on Paper Chromotatography.
What is the Stationary Phase?
The material that does not move, the ‘Mobile Phase’ is placed and moves on this.
What is the Mobile Phase?
The solute (and solvent) that moves through/across the ‘Stationary Phase.
Why do some substances have a longer ‘Retention Time’ than others?
The heavier a substance is, the longer it will take to adsorb. Polarity also affects adsorption as less polar substances are more mobile.
What is Retention Time?
The time taken for a compound to be identified.
What does a Chromatogram measure?
The ‘Retention Time’, the substance and the amount of identified substance.
What is GLC and how does it work?
Gas Liquid Chromatography is the process of finding compounds within a vaporised substance by using an inert gas to carry the sample. The tube that the sample is being carried through is coated with fine granules of high BP liquid. The liquid is the ‘Stationary Phase’
What is different from a GLC and HPLC chromatogram?
The spikes’ height and area give the quantity of identified substance for HPLC. Organic molecules less than 300g/mol are tested with GLC. HPLC only uses organic molecules.
What is HPLC?
High Performance Liquid Chromatography is the process of finding compounds within organic molecules with less than 300g/mol with BP too high for GLC.
