The inductively coupled plasma mass spectrometry (ICP-MS) is a relatively young technique, which allows the simultaneous detection of almost all elements of the periodic table. The main advantage of this method are the low detection limits. ICP-MS technique combines a high temperature argon plasma (6000 to 8000°K) as a highly efficient ion source with a mass spectrometer. The plasma is generated in a quartz torch. Solutions of samples are introduced into the plasma via a nebuliser as a fine aerosol. When the aerosol reaches the plasma the sample gets completely volatilised, atomised, and ionised under atmospheric pressure. This process produces a cloud of positively charged ions. The sample ions are transferred into a vacuum system containing a mass filter. In the analyser the ions are separated according to their mass-to-charge ratio (m/z). The ions are detected by an secondary electron multiplier. For quantitative analysis the count rate obtained for a certain ion is proportional to its concentration. Interferences in ICP-MS can be of spectroscopic or non spectroscopic nature (Jarvis et al., 1992). Spectroscopic interferences result from signals of oxides (MO+), doubly charged ions (M2+), hydroxides (MOH+), argides, isobaric overlaps, and of molecules with the same ratio of mass and charge such as the element of interest. Non-spectroscopic interferences are either physical effects which result of the solids present in a solution or analyte suppression and enhancement effects which result from influences of matrix elements in the sample on the yield of formed ions (Jarvis et al., 1992). Molecular and doubly charged interferences can be minimised by tuning of the ICP-MS. When the ICP-MS method is combined with hydride generation a powerful method with very low detection limits can be achieved
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