Ionisation in mass spectrometry

Argon plasmas are used in optical emission spectrometry to atomise and ionise elements leading to the emission of characteristic spectral lines. Hence, a plasma torch (7-8 000 K) can be used for ionisation in mass spectrometry. Ions produced in the plasma are introduced into the mass analyser through a small orifice (called a skimmer) placed in the axial direction. Because the mass spectrometer is operated under a vacuum, the ions are sucked into the mass analyser through the skimmer. An aqueous solution of the sample can be aspirated into the plasma or, alternatively, the plasma can be placed at the exit of a gas chromatograph (e.g. speciation of organo-metallic compounds by GC/ICP-MS). Since all chemical bonds are broken in the plasma, the only accessible information is that concerning the concentration of monoatomic ions (Fig. 16.19). 

Spectroscopy Chemical Ionisation in Mass Spectrometry Chromatography-MS, Methods Hyphenated Techniques, Applications of in Mass Spectrometry Inductively Coupled Plasma Mass Spectrometry, Methods Mass Spectrometry, Historical Perspective MS-MS and MS" Photoacoustic Spectroscopy, Applications. 

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