Themes > Science > Chemistry > Analytical Chemistry > Methods and Instrumentation > Inductively Coupled Plasma
An inductively coupled plasma (ICP) is a very high temperature (7000-8000 K) excitation source that efficiently desolvates, vaporizes, excites, and ionizes atoms. Molecular interferences are greatly reduced with this excitation source but are not eliminated completely. ICP sources are used to excite atoms for atomic-emission spectroscopy and to ionize atoms for mass spectrometry.
Instrumentation -- The sample is nebulized and entrained in the flow
of plasma support gas, which is typically Argon (Ar). The plasma torch
consists of concentric quartz tubes. The inner tube contains the sample
aerosol and Ar support gas and the outer tube contains flowing gas to keep
the tubes cool. A radio frequency (RF) generator (typically 1-5 kW @ 27
MHz) produces an oscillating current in an induction coil that wraps
around the tubes. The induction coil creates an oscillating magnetic
field, which produces an oscillating magnetic field The magnetic field in
turn sets up an oscillating current in the ions and electrons of the
support gas (argon). As the ions and electrons collide with other atoms in
the support gas.
Instrumentation
-- As in AAS, the sample must be converted to free atoms, usually in a
high-temperature excitation source. Liquid samples are nebulized and
carried into the excitation source by a flowing gas. The excitation source
must desolvate, atomize, and excite the analyte atoms.
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