Mass Spectrometers (MS)
 TRIO-2000 Quadrupole Mass Spectrometer
The Micro Mass TRIO-2000 Quadrupole Mass Spectrometer suitable for
determining the molecular mass and chemical composition of compounds
having a mass/charge ratio of up to 4000. This is a more sophisticated
mass spectrometer than the GC-MS described below, capable of better
molecular mass resolution as well as the detection of higher molecular
masses. The mass spectrometer is equipped with multiple inlet methods,
including electrospray, chemical ionization and atmospheric ionization,
and can be connected directly to a GC (gas chromatograph) or HPLC
(high pressure liquid chromatograph) source. This instrument greatly
expands our ability to carry out research projects in all areas of
chemistry, including biochemistry and environmental chemistry. Examples
of current projects include studies of the complexation of double
stranded DNA by environmental pollutants, detection of isolated biologically
active proteins, and an investigation of the ionization process that
occurs during electrospray ionization. If you would like more information
about the capabilities of this instrument, please contact Dr.
Catherine Bentzley.
Varian Gas Chromatograph-Mass Spectrometer
The GC-MS is a combination instrument that permits sequential separation
of a mixture of chemicals found after a chemical reaction is carried out, or
from a mixture obtained as the result of chemical extraction of a plant, forensic
or environmental sample. Volatile components of the sample are put through a
gas chromatograph, followed by identification of the compounds contained in the
sample by the characteristic mass spectrum exhibited. Located in one of our
instrument rooms shown here, is the Varian GC-MS (next to Dr. Schaefer), together
with a Varian stand-alone GC.
The GC-MS, and the GC, are workhorse instruments designed to simplify
the identification of unknown chemicals and is vital for any work
involving the characterization of an unknown material in traditional
organic chemistry, environmental chemistry, forensic chemistry,
or drug analysis. At USP, this instrument is often used by students
in the Pharmacognosy graduate program for the analysis of pharmacologically
active compounds extracted from plants. If you would like more information
about the capabilities of this instrument, please contact Dr.
Fred Schaefer.
Mass Spectroscopy - What does it do?
Mass spectrometry is another of the very powerful tools available
for the determination of the structure of a molecule through the
measurement of the mass of the intact molecule and the mass of the
fragments produced under certain specific experimental conditions.
The fragmentation pattern obtained is diagnostic of what types of
atom groupings are present in the molecule. For example, if a fragment
with a mass of 17 amu is obtained, that would suggest that the molecule
contains the hydroxyl group (-OH) attached somewhere on the carbon
framework. Similarly, if a fragment with a mass of 31 amu is obtained,
that would suggest that the methoxy group (CH3O-) is
present. By analyzing the masses of all the fragments obtained,
it is usually possible to reconstruct the overall structure of the
molecule.
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