Post Top Ad

Your Ad Spot

lundi 16 mars 2020



what is Spectroscopy
Spectroscopy is the study of  and electromagnetic radiation. Spectroscopic techniques are widely used for the structure elucidation of the compounds in organic chemistry.

Techniques of Spectroscopy
There are five Techniques of Spectroscopy 

  • Mass Spectrometry (MS): use to determination of molecular mass and molecular formula X.
  • Infrared (IR): use to determination of Functional group
  • Ultra violet (UV): use to determination of visible spectroscopy,, degree of unsaturation.
  • Nuclear Magnetic Resonance (NMR): use to determination of type of proton (H)
  • X-rays: use to determination of structure with stereochemistry
what is Mass Spectrometry (MS)?

Mass spectroscopy is the method is a powerful analytical technique widely used by chemists, biologists, medical researchers, and environmental
for determination the molecular mass and formula the mass of a molecule, or of different fragments of that molecule
of the compound and also can give information about structure. It’s a destructive technique that’s why it is called spectrometry other techniques are constructive so called spectroscopy.

the principle of MS
  • Different element are uniquely identify through their mass.
  • Different masses for example CH3CH2OH  Ethanol molecular and CH3OH Metanol molecular 
In mass spectrometer molecule is vaporized and ionized

The molecule is converted into molecular ion (X+•) in the ionization by heating or bombarded with the beam of high energy electron e. At the result the loss of electron e from sample and formation of positive ion + .
X   +   e ————————->   X+•
This molecular ion is unstable that’s why it decompose and forms fragments of radicals (. ) and captions (+). They have lower molecular weight then molecular ion.

It is electrically heated filament which provides the high energy electron beam.

    Possible reaction in ionization 
    • X + e —————————–> X+ + e
    • X + e —————————–> X + e
    • X + e —————————–> X +  e
    • Fragments
    Negative ion( )will be attracted by repeller plate. Accelerating plates will be attracting the positive ion (+)
    Repeller plates
    Vacuum pump
    Accelerating plates
    The most abounded peak is called base peak. For example CH3 (CH2)10 CH3 alkanes spectrum is

    example CH3 (CH2)CH3

    Mass Spectrometry for Isotopes
    Most elements have major isotopes for example chloromine. In mass spectrometry A ratio of molecule  to molecular ion is 2:2 its shows a presence of a single chloromine atom in compound. For example 2-chloropropane the mass spectrum is following

    1 commentaire:

    Post Top Ad