Mass spectrometry is primarily used to determine the molar mass and formula for a
- high performance chromatography to separate compounds, mass
spectrometry to analyze the structure of the compounds.
- Electron impact ionization: generate an intermediate that is both a cation
and a radical.
- Radical : unpaired electron; Cation: bears a positive charge
- Fragments results, neutral radical and a charged carbocation.
- Ions are deflected by magnetic field. Charge move and interact with a
magnetic field, accelerated to a negatively charged plate, bent over to one
side and arrive at the detector.
- The charge is constant, +1.
- The mass spectrum is to measure the amount of atoms arrive at the detector
as a function of mass. Charge to mass ratio.
- X axis is mass. m/z (mass to charge ratio) z:charge
- m/z measure the mass of cation.
- For an unknown compound, read the mass spectrum, and
then get the molecular weight.
- Read the peak furthest to the right. The smaller bars are
fragment ions, created by the fragments from the parent
ion, losing hydrogen ions. 12 is just the carbon atom. 13-15
is C with H atoms. 17 is a result of an isotope C17.
- IN reading mass spectrum, looking for the highest mass to
charge ratio. To determine molecular weight, rec