Mass spectrometry (MS) is a commonly used identification tool, which has far ranging applications. Traditional mass spectrometry applications have included trace metal detection in the environment and in foodstuffs. The technique employs a mass spectrometer which is capable of generating ions from atoms or molecules (the source). The separation of these ions, by virtue of their mass-to-charge (m/z) ratio, allows discrimination between chemical compounds or elements (the analyser).
There are many methods of ionisation including the so-called �soft� procedures, routinely employed in biological molecule analyses, of MALDI (matrix assisted lazer ionisation/desorption ionisation) and ESI (electrospray ionisation). The former utilises a lazer beam to ionise a matrix containing the analyte. ESI is achieved by spraying a solution of the sample through a conducting capillary at a high potential.
In addition, there are different forms of ion discrimination. A quadrupole instrument involves the application of DC and AC voltages to 4 parallel rods, resulting in the creation of a �sieve� and thus, only transmission of ions of a defined m/z value can be accomplished. However, all ions can be transmitted if a Rf field is applied.
Alternatively, time of flight (TOF), often used with MALDI, concerns the acceleration of ions (under vacuum). The time taken for the ions to reach the detector is related to their m/z value.
Since mass spectrometry is a detection technique, separation procedures are commonly interfaced with a mass spectrometer (Click 
for an image - 70KB). The extraction material containing the atom or molecule of interest will dictate the separation technique and these include gas or liquid chromatography.
(Click for a diagram showing LC/MS steps - 38KB)
Current interest in mass spectrometry has increased due to the advent of new ionisation techniques, instrument technology advances, including high throughput platforms and its application in the evolving field of proteomics. Recent research has involved the employment of mass spectrometry techniques in order to quantify, size and sequence DNA and to identify polymorphisms for pharmacokinetic purposes. One of the leading manufacturers
within this field is Micromass.
Click here for more detailed information on LC/MS.