Chromatography Flashcards
What are the 3 types of chromatography?
-Thin Layer
-Column
-Gas
What is chromatography used for?
To separate and identify compounds in a mixture
What is the stationary phase (what is the plate coated with) in TLC?
SiO2/Al2O2
How can colourless substances be identifies in TLC?
-Iodine :- Iodine vapour dyes the chromatogram purple
-Fluorescent dyes will be blocked by colourless substances so shows as a spot under UV light
What can change the Rf value in TLC?
-Temperature
-Solvent
-Plate used
What is the column packed with in column chromatography?
SiO2/AlO2
What happens in Column chromatography?
The mixture is ran through the column whilst solvent is continuously running through
How are substances identified in column chromatography?
The substances move through the column at different rates so can be collected at different time
What does the mixture have to be in order to be used in gas chromatography?
Volatile
What is the mixture carried by in gas chromatography?
Inert gas (doesn’t react)
What is the set up in gas chromatography?
Thin column wound up and heated in an oven
How are substances identified in Gas chromatography?
The retention time -> the time taken to travel through the column
What does the gas chromatography spectra show?
-Retention times which can be compared to a library of values
-Area under the peaks shows the amount of each substance
What dye can be used for TLC?
Nihydrin
