• In Spectrocopic technique sample may be recollected or while in the spectrometric techniques it is not possible. When a compound is barotrged by high energy neutrons or electron its ionization takes place and cation redical species is formed. Further bambarment of neutrons or electron on the cation redical species can break it in small fragments. Small Fragments may be charged or neutral These charged fragments are Excreted by applying potential to send them in a magnetic field.
  • In Magnetic Field these Fragments are separated on the basis of their M/E or M/Z Value.
  • In single cation radical species M+. Z=1 and electron also =1
  • In population of the fragments (intensity) is plotted against m/z value of the fragments is known as mass spectrum.
  • Malecular Mass can be study by this spectroscopy.In the mass spectrum line corresponding to m/e value of M+. is treated molecular ion peak and its m/e value indicates Molecular Mass of the compound under investigation.This is most important application of mass spectrometry.
  • The Peak with highest intensity is treated as base peak and its intensity is considered to be 100%.The intensity of other peaks is assign relative to it.In general molecular ion peak doesn’t appear in spectrum or It appear very low intensity.
  • There are certain rules by which position molecular of molecular ion peak can identified and on the basis of its m/e value molecular weight of the compound is reported.
  • N- rule- If a compound has add number of N Atom then its molecular weight will be add. On the other hand if there is no N- atom or even number N atom are present in the compound its molecular weight will be even.
  • CH3- NH2 =29   CH3-CH3=30


Author: Pooja Gupta