ABSTRACT
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In this method the analyzed sample must be in solution. Biological samples are dissolved usually by application of concentrated acids.• In the instrument the solution is evaporated and turned into plasma consisting of excited atoms and atomic ions. The atoms or ions can be detected either by their emitted light when returning to their ground state (ICP-AES stands for Atomic Emission Spectrometry), or the ions can be determined with a mass spectrometer (ICP-MS). ICP-MS is more sensitive by about two orders of magnitude than ICP-AES, and the sensitivity of most of the
elements is about the same (0.02 to 0.2 ppb). However, for masses lower than 80 Da there are interferences due to cluster ions and compounds ions such as MO+, MCl+, MOH+, and MOH2+. Thus, for example, Mg is more sensitive by ICP-AES than by ICP-MS, due to the unusually high sensitivity of Mg to ICP-AES (0.1 ppb compared to 1 to 250 ppb for other elements), and the low sensitivity of Mg to ICP-MS (0.7 ppb compared to 0.002 to 0.1 ppb for most elements). ICP-MS is much more expensive than ICP-AES. The use of ICP-MS enlarges considerably the number of elements which can be directly determined in body fluids. In serum, ICP-AES allows the direct determination of only Na. Ca, Mg. Fe, Cu, and Zn, whereas with ICP-MS many other elements can be determined, e.g., Pb, Cd, and Hg.
