Mass spectrometry Flashcards
how does mass spectrometry work
It measures the mass to charge ratio of molecules
every atom has a
unique proton and electron number
NMR
atomic resolution data
slow
limited for mixtures
0.1-5mg
mass spectrometry
molecule resolution
fast
mixtures and pure compounds
single molecule ng/pg
mass spec uses
historical
biological
mass spec can show
isotopic abundancy
the effects of isotopes is
addictive
the bigger the molecule the
greater the effect of isotopes will have
accurate mass
mass of principle isotope
monisotopic
soft ionisation
too light not enough energy
no fragmentation
hard ionisation
fragmentation
electron ionisation
hard
Pi systems
beam of e- wavelength close to the wavelength of the bond
it interfers with the electrons in the bond, causing a lose of an e-
chemical ionisation
the reagent undergoes electron ionisation.
the reagent gas collides with the sample which transfers
a proton to the sample.
electrospray ionisation
sample is added with ionic compound.
pass through fine capillary needle
needle is attach high voltage at a high potential.
the solution is aerosol.
solution droplet enter a vaccuum.
the solvent evaporates
columbic explosion, the like ions repel each other
quadrople mass analyser
scientist controls the rod via DC voltage.
only desired ion pass through rods.
other ions are neutralised by rod
TOF
Accelerated by electric field.
ionic drift
detectation
ch4, ch3ch3, etc for m+ 1 peak
the percentage of isotope doubles, 1.1, then 2.2 etc.
how to find number of carbons?
peak/highest peak * 100/percentage of isotope abundancy
how to find if a molecule has a double bond?
carbon number - h/2 + n/2 , + 1
if it is an integer then there is a high chance.
within electronic energy levels
there will be vibrational energy
within vibrational energy levels
there will be rotational energies
transition between e energy levels occur with
x rays
transition between v energy levels happen in
IR
