MASSspectrometr

yDr. Kristoffer Rem Labing-isa

Massachusetts Institute of TechnologyDean, College of Science

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Early called as ‘spectrograph’

Etymology

Spectrograph had became part of the International Scientific Vocabulary

*International Scientific Vocabulary comprises scientific and specialized words whose language of origin may or

may not be certain, but which are in current use in several modern languages.

Spectrograph, ‘spectr’ from spectrum and ‘ograph’ from photograph

Etymology

Spectrograph records a spectrum on a photographic plate

Mass spectroscopy is discouraged due to confusion with ‘light spectroscopy’

Mass-Spec or MS

Mass Spectrometry

Analytical technique that measures the mass to charge ratio of charged particle

Used for determining masses of particles, elemental composition, and

elucidating the chemical structures

Eugen Goldstein observed rays in gas discharges under low pressure that

travels from anode to cathode

History

He named it ‘kanalstrahlen’ or the canal rays, an anode ray

Wilhelm Wien found that strong magnetic fields deflect the canal rays

History

J. J. Thomson later improved the work of Wien.

First application of mass spec is on the amino acids and peptide

MS Instrument

Converts gas phase sample molecules into

ions.

Ion Source

*In electrospray ionization, ions that exist in solution is converted into

gas phase

MS Instrument

Sorts or organizes the ions according

to their masses.

Mass Analyzer

MS Instrument

Measures the value of an indicator

quantity, thus provides data for calculating the

abundances of each ion present

Detector

MS Procedure

A sample is loaded onto the MS instrument and undergoes

vaporization

First Step

MS Procedure

Components of the sample are ionized by one of a variety of

methods such as impacting them with an electron beam

Second Step

MS Procedure

Ions are separated according to their mass-to-charge ratio in an analyzer

by electromagnetic fields

Third Step

MS Procedure

Ions are detected, usually by a quantitative method

Fourth Step

MS Procedure

The ion signal is processed into mass spectra

Fifth Step

Creating Ions

A sample is loaded onto the MS instrument and undergoes

vaporization

Creating Source

The analyte is ionized by chemical ion-molecule reactions during

collisions in the source

Chemical Ionization

Mass Selection

Ions are separated according to their mass-to-charge ratio in an analyzer

by electromagnetic fields

Mass Selection

Mass analyzers separate the ions according to their mass-to-charge

ratio.

F = ma

Mass Selection

F = ma

Mass Selection

The analyte is ionized by chemical ion-molecule reactions during

collisions in the source

Chemical Ionization

AnalogyA sample of sodium chloride

Vaporized NaCl

Ionized NaCl

Na23Cl35 Cl37 Na23

Analogy

Na23

Cl35

Cl37

Na23

Na23

Cl35

Cl37Na23

Analogy

Na23 Cl35 Cl37

Lighter ions get deflected by the magnetic force more than

heavier ions