An inductively coupled plasma (ICP) is a very high temperture (7000-8000K) 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.
The sample is nebulized and entrained in
the flow of plasma support gas, which is typically 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 radiofrequency (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