Mass Spectrometry Flashcards
Describe the process of mass spectrometry
1) Vaporised / atomised - turned into gaseous particles.
2) Ionised - create singly charged positive ions
3) Accelerated - made to move rapidly
4) Deflected - made to follow a path by a magnetic field
5) Detected - Counted as the ions hit an ion detector,
What determines how far an ion is deflected
Its mass
What is the base peak?
The peak at 100 - for the most stable ion
What is the label for the horizontal axis?
M/Z values (mass to charge ratio)
What is the label for the vertical axis?
Relative abundance
What is the molecular ion peak (M+)
last major peak in the spectrum with the highest M/Z value
What is the fragmentation pattern?
The pattern of peaks with m/z values lower than the molecular ion peak.
What is the M+1 peak?
A small peak 1 m/z value about the molecular ion peak. Caused by the presence of a Carbon 13 atom in a molecular ion.
What must you put after each fragment?
A + needs to be put after each fragment as they are all ionised before they are put in the mass spectrum.
What is the fragmentation pattern?
The peaks before the molecular ion peak are caused by the molecule fragmenting during vaporisation and ionisation. Unique to particular molecules.
When identifying peaks in a spectrum what are the last bonds to be broken?
C-H bonds.
How often do Carbon 13 atoms occur and what does this tell us?
They occur in 1.1% of carbon atoms. The relative abundance of the M+1 peak when compared to the M+ peak tells us how many carbon atoms there are in the molecule. e.g. 1.1% = 1 carbon, 2.2% = 2 carbons and so on.
What does high resolution mass spectrometry tell us?
Measures the mass of atoms to many decimal places and this enables us to identify peaks without any ambiguity..
