Inductively Coupled Plasma Atomic Emission Spectroscopy: Principle

Inductively coupled plasma, or ICP, is a widely used plasma source in atomic emission spectroscopy.

It employs a plasma torch consisting of three concentric quartz tubes with flowing argon gas, which is ionized by a spark from a Tesla coil.

The resulting ions and electrons interact with the fluctuating magnetic field created by a water-cooled radio-frequency induction coil.

This interaction leads to ohmic heating, forming a high-temperature argon plasma with a brilliant white core and a flame-like tail.

In ICP–AES, a concentric glass nebulizer is used to transport the sample with the help of high-velocity argon gas to form fine droplets by the Bernoulli effect—that enters the plasma.

Alternatively, electrothermal vaporization can be employed, where the sample is vaporized in a furnace, and an argon stream carries it into the plasma.

The plasma source offers various advantages, like atomization in a chemically inert environment that prevents refractory oxide formation and prolongs the analyte's lifetime.

Additionally, it maintains a relatively uniform temperature cross-section, reducing occurrences of self-absorption and self-reversal.