ICP-MS
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ICP-MS (Inductively Coupled Plasma Mass Spectrometry) is a type of mass spectrometry that is highly sensitive and capable of simultaneous analysis of a range of metals at below the parts per a trillion level. It is based on coupling together an inductively coupled plasma as an ion source with a mass spectrometer as a method of detecting the ions.
1. ICP (Inductively Coupled Plasma) - this is a high temperature plasma (ionised argon) sustained with a radiofrequency electric current, which acts to produce ions.
2. MS (Mass Spectrometry) the ions from the plasma are extracted through a series of cones into a mass spectrometer, usually a quadrupole. The ions are separated on the basis of their mass-to-charge ratio and a detector receives an ion signal proportional to the concentration.
The concentration of a sample can be determined through calibration with elemental standards. ICP-MS also lends itself to quantitative determinations through isotope dilution, a single point method based on an isotopically enriched standard.
Other mass analyzers coupled to ICP systems include double focusing magnetic-electric sector systems with both single and multiple collector, as well as time of flight systems (both with axial and orthogonal accelerators).
ICP-AES (Atomic Emission Spectrometer) uses the ICP to produce excited atoms which emit radiation (at a wavelength characteristic of a particular element), which can then be detected (signal is proportional to concentration).