Mass Spectroscopy

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Brief introduction about Mass Spectroscopy & its Instrumentation.

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Mass Spectroscopy

  1. 1. Bhavana vedantam, Chalapathi Institute Of Pharmaceutical Sciences 1
  2. 2. Contents Introduction Basic principle Advantages & Disadvantages Instrumentation Applications Chalapathi Institute Of Pharmaceutical Sciences 2
  3. 3. • Mass spectroscopy deals with the study of the charged molecules & fragment ions produced from a sample exposed to ionizing conditions, & also of the relative intensity spectrum which results from the correlation of the ions with their mass to charge ratio. • MS concept is first introduced by scientists Sir.J.J. Thomson and Wiens. Powerpoint Templates Page 3
  4. 4. Principle to 10 When gaseous sample under 10 -7 -5 mm Hg pressure bombarded with electron beam(70ev), loss of electron from π orbital takes place resulting in the formation of ions and ion fragments. Chalapathi Institute Of Pharmaceutical Sciences 4
  5. 5. Molecular ions Fragment ions Isotopic ions Types of ions Rearrangement ions Multiple charged ions Negative ions Meta stable ions Chalapathi Institute Of Pharmaceutical Sciences 5
  6. 6. Chalapathi Institute Of Pharmaceutical Sciences 6
  7. 7. Molecular weight & formula determination Qualitative & Quantitative analysis Sample destruction Sample should be in gaseous form Less amount of sample Complex & high cost Less than 1min. for analysis Chalapathi Institute Of Pharmaceutical Sciences Should maintain vacuum throughout the process 7
  8. 8. Chalapathi Institute Of Pharmaceutical Sciences 8
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  10. 10. solid Directly into the chamber with low vapour pressure by means of probe. e.g. steroids, carbohydrates Chalapathi Institute Of Pharmaceutical Sciences Liquid Vaporized with the help of heat inlet system. e.g. sugars , amino acids Gas Directly inleted & vaporized 10
  11. 11. Ionization techniques Electron impact ionization Chemical ionization Chalapathi Institute Of Pharmaceutical Sciences Field ionization Laser desorption technique Fast acting bombardme nt 11
  12. 12. Electron beam(70ev) produced from electrically heated tungsten or rhenium filament is applied perpendicular to the sample and results in fragmentation. *sample destruction. Chalapathi Institute Of Pharmaceutical Sciences 12
  13. 13. Reactive gases bombards with electron beam Reactive species are formed which colloid with sample molecules +vely charged ions are produced Chalapathi Institute Of Pharmaceutical Sciences 13
  14. 14. Fast atoms of Xe/Ar collides with neutral gas atoms Transfer of energy to gas atoms Chalapathi Institute Of Pharmaceutical Sciences High energy gas atoms directed towards sample Energy transfer to sample 14
  15. 15. Eg: MALDI(Matrix Assisted Laser Desorption Ionization) • TOF (Time Of Flight) analyzer Advantages : No direct contact of sample and electron Easy to operate laser Chalapathi Institute Of Pharmaceutical Sciences 4-hydroxy cinnamic acid 15
  16. 16. Contd……. Matrix + + + + Laser Analyte + + + + + -+ + + + + + Laser is bombarded with Matrix containing the sample Energy transfer to sample Expansion of matrix + Chalapathi Institute Of Pharmaceutical Sciences 16
  17. 17. +ve ions at the end of chamber Bombarded with accelerating potential(2-8kV) Analyzers are used to deflect ions based upon m/e ratio. Deflection in magnetic field according to velocity & m/e Chalapathi Institute Of Pharmaceutical Sciences 17
  18. 18. Chalapathi Institute Of Pharmaceutical Sciences 18
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  20. 20. Magnetic field Magnetic field & electric field Ions of same mass number are separated Ions of same mass no.& same velocity are separated Less sensitivity(10-1) Highly sensitive(10-12) Chalapathi Institute Of Pharmaceutical Sciences 20
  21. 21. Chalapathi Institute Of Pharmaceutical Sciences 21
  22. 22. Faraday Cup detector Least sensitive. Cup will capture the ion. Chalapathi Institute Of Pharmaceutical Sciences Photomult iplier detector sensitive. 1000 times greater than faraday cup. Photogra phic detectors Most sensitive. Used for high resolution. 22
  23. 23. APPLICATIONS Molecular weight,formula & elemental composition determination Identification of an unknown compound Distinction between cis & trans- isomers Identification of fragmentation pattern Impurity detection As LC-MS in analysis of proteins Chalapathi Institute Of Pharmaceutical Sciences 23
  24. 24. • Mass spectrometry is used for the study of charged molecules and fragment ions. Thus it is useful for the identification of an unknown compound. Chalapathi Institute Of Pharmaceutical Sciences Page 24
  25. 25. • Elementary organic spectroscopy by Y.R.Sharma fourth edition 2007,by Rajendhra Ravindra printers page(280-291). • Spectroscopy of organic compounds by P.S.Kalsi sixth edition, by New age international Pvt. Ltd. Page(415-439). • Gurdeep R.Chatwal Sham K. Anand Instrumental Methods Of Analysis, Fifth addition, Himalaya publishing house Pvt . Ltd. • Pharmaceutical analysis (INSTRUMENTAL METHODS) by Dr . A.V.Kasture, ninth edition.
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