1. BY
MADHUKAR
11GQ1R0028
Mass spectroscopy

2. INTRODUCTION
 Mass or molecular weight of a compound can be
found in several ways .one such technique is using
mass spectrometer
 It is an analytical chemistry technique that helps
identify the amount and type of chemicals present in
a sample by measuring mass-to-charge ratio and
abundance of gas-phase ions

3. Principle
 A mass spectrometer generates multiple ions
from the sample under investigation
 This molecular ion undergoes fragmentation.
Each primary product ion derived from the
molecular ion, in turn, undergoes fragmentation,
and so on.

4.  The ions are separated in the mass spectrometer
according to their mass-to-charge ratio, and are
detected in proportion to their abundance. A mass
spectrum of the molecule is thus produced.
 It displays the result in the form of a plot of ion
abundance versus mass-to-charge ratio

6. Obtaining mass spectra consist of 2
types;
 Conversion of neutral molecule into a charged
molecule, preferably to a positively charged
molecule.
 Separation of the positively charged fragments
formed, based on their masses, by using electrical
or magnetic field or both.

7. Instrumentation
The instrument consists of three major components:
Ion Source: For producing gaseous ions from the
substance being studied.
Analyzer: For resolving the ions into their characteristics
mass components according to their mass-to-charge ratio.
Detector System: For detecting the ions and recording
the relative abundance of each of the resolved ionic species.

8. Components of a Mass Spectrometer

9.  In addition, a sample introduction system is
necessary to admit the samples to be studied to
the ion source while maintaining the high
vacuum requirements (~10-6 to 10-8 mm of
mercury) of the technique; and a computer is
required to control the instrument, acquire and
manipulate data, and compare spectra to
reference libraries

11. With all the above components, a mass spectrometer
should always perform the following processes;
 Separate these ions according to their mass-to-charge ratio in
the mass analyzer.
 Eventually, fragment the selected ions and analyze the
fragments in a second analyzer.
 Detect the ions emerging from the last analyzer and measure
their abundance with the detector that converts the ions into
electrical signals.
 Process the signals from the detector that are transmitted to
the computer and control the instrument using feedback.

12. Chromatographic techniques combined with mass
spectrometry
 An important enhancement to the mass
resolving and mass determining capabilities of
mass spectrometry is using it in tandem with
chromatographic separation techniques.

13. Gas chromatography
A common combination is gas chromatography-mass
spectrometry (GC/MS or GC-MS). In this technique, a gas
chromatograph is used to separate different compounds.
This stream of separated compounds is fed online into the ion
source, a metallic filament to which voltage is applied. This
filament emits electrons which ionize the compounds.
 The ions can then further fragment, yielding predictable
patterns.
 Intact ions and fragments pass into the mass spectrometer's
analyzer and are eventually detected.

15. Liquid chromatography
 Indianapolis Museum of Art conservation
scientist performing liquid chromatography–
mass spectrometry.

16.  Similar to gas chromatography MS (GC/MS), liquid
chromatography-mass spectrometry (LC/MS or LC-MS)
separates compounds
 chromatographically before they are introduced to the ion
source and mass spectrometer. It differs from GC/MS in that
the mobile phase is liquid, usually a mixture of water and
organic solvents, instead of gas.
 Most commonly, an electro spray ionization source is used in
LC/MS. Other popular and commercially available LC/MS ion
sources are atmospheric pressure chemical ionization and
atmospheric pressure photo ionization.
 There are also some newly developed ionization techniques
like laser spray.

18. Applications
Mass spectrometry has both qualitative and
quantitative uses.
Structure of elucidation;
Using nitrogen rule, peak matching, fragmentation
pattern of a compound and % abundance of isotopes,
structure of elucidation of organic compounds can be
done.
Detection of impurities;
Impurities present can be detected by the additional
peaks, highest value of mass peaks then compound
itself, & from the fragmentation pattern

19. MS is now in very common use in analytical laboratories that
study physical, chemical, or biological properties of a great
variety of compounds.
As an analytical technique it possesses distinct
advantages such as:
Increased sensitivity over most other analytical techniques
because the analyzer, as a mass-charge filter, reduces
background interference
Excellent specificity from characteristic fragmentation patterns
to identify unknowns or confirm the presence of suspected
compounds, Information about molecular weight.