Mass spectrometry is a highly accurate method for identifying the chemical samples and calculating the molecular weight. It is based on the determination of the ‘mass spectrum’, which is a chart showing the mass/charge ratio of the ions resulting from the decomposition of the sample.

The principle is the following: molecular samples are broken into ions that are accelerated through a magnetic field. The ions with different mass/charge ratio differ either in their trajectory or in their speed under external magnetic fields.

The components of a mass spectrometer are: an ion source that breaks the sample into ions, an analyzer or ion sorter, and a detection system. Vacuum conditions are required in order to achieve high resolutions during the mass analysis process.

Mass spectrometers are classified according to the mass analysis method and the ion generation method. Triple quadrupole, quadrupole ion trap and time of flight are the most popular mass analyzers. Some of the most employed ionization methods are: electrospray ionization (ESI), matrix assisted laser desorption - absorption (MALDI), atmospheric pressure chemical ionization (APCI). Depending on the application, each mass spectrometer incorporates a specific combination of mass analyzer and ionization source. Some mass spectrometers even use combined methods for mass analysis (e.g. quantum ion trap – time of flight analyzers).

The main advantages of this technique are versatility, high accuracy in quantitative and qualitative measurements at relatively low analysis times.

Mass spectrometry is used in a plethora of applications ranging from environmental analysis to forensics.

Of special interest are the “omics” sciences: proteomics, genomics and metabolomics (the study of the human metabolic products). In nanotechnology this method is a tool for the study of deposition techniques that involve ion transport (e.g. pulsed laser deposition and magnetron sputtering). It is also used for the study of nanoclusters with dimensions less than 10nm.