C4.2.4 - Instrumental Methods Of Analysis Flashcards
What is an instrumental method of analysis?
Relies on a machine to carry out an analysis of a substance
What are the advantages of instrumental method?
Sensitivity - Can analyse very small amounts of substance
Accuracy - Very accurate
Speed - Very quick and can run all the time
What does a gas chromatography show?
Different substances in a mixture
How do you interpret a gas chromatogram?
Each peak represents a substance present.
Areas under each peak show the relative amount of each substance.
Retention time is the time taken for the substance to travel through the chromatography column. (Different for each substance)
What does a mass spectrometer measure?
Masses of atoms and molecules
What is a mass spectrometer used for?
It is used to analyse the relative amounts of different isotopes of an element and the structure of molecules.
How does a mass spectrometer work?
The sample molecules are ionised by the machine to form molecular ions. These may break up to form fragments which the machine can separate and detect
How do you interpret a mass spectrum?
Each peak represents a fragment of the molecule.
The peak on the far right represents the molecular ion.
The mass to charge ratio of the molecular ion peak is equal to…
…the relative formula mass of the molecule
