Mass spectrometer converts molecules to ions under vacuum so that they can be moved about and manipulated by external electric and magnetic fields. These ions are then separated and determined. Separation is achieved on different trajectories of moving ions in electrical and/or magnetic fields. *Electrospray Ionization (ESI) *Matrix-Assisted Laser Desorption/Ionization (MALDI) *Time-of-Flight (TOF) Mass Analyzer Recent advances in the application of mass spectrometry in food-related analysis *LC-MS coupling techniques *HPLC-MS coupling techniques *MALDI-TOF-MS *ESI-MS

1. MASS SPECTROSCOPY
- Meesha Singh

2. Introduction
Basic Principle:
 Mass spectrometer converts molecules to ions under
vacuum so that they can be moved about and manipulated
by external electric and magnetic fields.
 These ions are then separated and determined. Separation
is achieved on different trajectories of moving ions in
electrical and/or magnetic fields.
 Associated components:
i. A small sample of compound is ionized, usually to
cations by loss of an electron- The lon Source
ii. The ions are sorted and separated according to their mass
and charge. - The Mass Analyzer
iii. The separated ions are then detected and tallied, and the
results are displayed on a chart.- The Detector

3. Instrumentation

5. Soft Ionization Techniques
Electrospray Ionization (ESI)
 Spray sample solution from a needle into an orifice in
the interface across a high potential difference.
 Heat and gas flows: to desolvate the ions existing in the
sample solution.
 It can produce multiple charged ions with the number of
charges tending to increase as the molecular weight
increases.
 Extremely useful for accurate mass measurement,
particularly for thermally labile, high molecular mass
substances (ie. proteins, oligonucleotides, synthetic
polymers, etc.)

7. Matrix-Assisted Laser Desorption/Ionization
(MALDI)
 Dissolve analyte in a solution containing an excess of a
matrix such as sinapinic acid or dihydroxybenzoic acid.
 Such matrix has a chromophore that absorbs at the laser
wavelength.
 Place a small amount of this solution is placed on the
laser target.
 The matrix absorbs the energy from the laser pulse and
produces a plasma that results in vaporization and
ionization of the analyte.
 Rapid and convenient molecular weight determination.

9. Time-of-Flight (TOF) Mass Analyzer
 For an ion accelerated by voltage V, the resulting
velocity is proportional to the mass-to-charge ratio. In a
Time-of-flight (TOF) mass spectrometer, ions are
detected on the basis of the time needed to travel a path
L.
 Ions of very high mass-to-charge (several hundreds of
kD) may be recorded after an appropriate length of time.
 Fastest available MS analyzer
 Well suited for pulsed ionization methods
 Highest practical mass range of all MS analyzers.

10. Recent advances in the
application of mass spectrometry
in food-related analysis

11. • Led to automation of various
procedures in food analysis.
• Structure elucidation of sugars
• Elucidate metabolism of
vitamins
LC-MS coupling
techniques
• Lipid analysis
• for e.g. characterization of the
acylglycerol and sterol fraction
• Analyze food samples such as
breakfast cereal and
concentrated beef and vegetable
extract.
• Analysis of polyphenolic
compounds
HPLC-MS
coupling
techniques

12. • Rapid and accurate evaluation of
the authenticity of milk
• Helpful in evaluating the presence
of cow milk in buffalo milk
samples and detecting the
addition of powdered milk to
fresh raw milk samples.
• Analysis of trypsin-digested
peptides of lectin
MALDI-TOF-MS
• Mass determination of milk
proteins
• Detection of modifications in
proteins caused by insertion,
deletion or modification of amino
acids
• Identification of genetic variants
and post-translational
modifications
ESI-MS

13. THANK YOU!! 