17.7.3 - Chromatography - HPLC and GC Flashcards
What does HPLC stand for?
High performance liquid chromatography.
In HPLC, what is the stationary phase usually made from and what state is it in?
Silica
Solid state
In HPLC the stationary phase is much smaller, how is this beneficial?
leads to better separation of components.
What is retention time?
The time taken from injection to detection.
In HPLC what variables can affect retention times?
The nature of the solvent
The pressure used
The temperature inside the column
What does GC stand for?
Gas chromotography.
In GC, what is the mobile phase?
An inert carrier gas
Usually nitrogen or hellium.
In GC, is the metal tube coiled or straight?
Coiled.
What happens in GC after the sample is injected?
The components vaporise and move through the coiled tube with the carrier gas.
In GC, what does the speed a component move through the tube depend on?
How strongly it’s attracted to the stationary phase.
What happens to the speed of movement through a tube and retention time in GC if a component has a weak attraction to the stationary phase?
Move through the tube quickly
Shorter retention time.
