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Mass spectrometry works by simultaneously vaporizing and ionizing
molecules, and then separating them according to differences in
their mass to charge ratios. A variety of methods and instruments
are employed for the ionization and separation processes, depending
on the molecules being analyzed. Each method of separation essentially
works because ionized molecules can be separated in space or time
by an induced acceleration that is reflective of the mass/charge
ratio of each molecule. Five techniques of mass spectroscopy utilizing
different ionization and separation methods are as follows. For
an overall explanation of mass spectrometry, take a look at Scimedia's
entry on MS. The links below will automatically bring you to the
Scimedia's entries on each type of MS instrument.
Fourier-transform
MS
Ion-trap
MS
Magnetic-sector
MS
Quadrupole
MS
Time-of-flight
MS
Bioanalytical chemists have taken mass spectroscopic analyses into the realm of large biomolecules, including proteins, oligonucleotides, and carbohydrates. Mass spectrometry allows the identification of biomolecules without the use of wet chemical techniques that would necessarily require larger samples. When dealing with quantities of proteins or nucleotide sequences present within single cells, mass spectrometry is an optimal, often automated identification technique.
Biomolecules, however, require a slightly altered version of
the spectrometry process, because polymeric integrity should be
maintained. Most ionization techniques cause the fragmentation
of molecules before they are detected, and this is often an integral
component of the identification process. However, for amino acid
and nucleotide sequences, proteases and nucleases are used to
fragment the polymers into predictable fragments, and these fragments
are then chemically ionized so as to not cause further fragmentation.
This allows the mass spectra to be pieced back together to reveal
sequence information. Protocols for protein identification by
mass spectrometry are outlined at PROWL's
site.
For further information and some research on biomolecule identification
by MS, or if you can't imagine how mass spectrometry and the National
Rifle Association are related, take a look at Justin
Hettick's MS Page.
Base Peak is a site that is dedicated to mass spectrometry, provided by a leading publisher in the subject. Journal databases, books, and links to other MS sites are included.
For questions and access to a mass spec newsgroup, see sci.techniques.mass-spec Homepage (look under Biochemistry Topics for archives).
Student MS Laboratories
& Literature Reviews on MS