(1) Measurement principle

ICP (Inductively Coupled Plasma) emission spectrometric analysis uses the inductively coupled plasma flame, at higher temperature (6,000 to 8,000K) than the burner used for the atomic absorption analysis (no more than 3,000°C), to cause dissociative excitation of measured substances in a broader range. The qualitative analysis will be performed by the wavelength position of atomic spectral lines emitted. The quantitative analysis will be performed by the emission intensity.

(2) Equipment

The analysis equipment is comprised of the followings: emission unit (for vaporizing sample and emitting light), spectroscopic unit (for dispersing emission spectral lines), and photometry unit (for measuring spectral lines). [Fig.1] illustrates the structure and mechanism of an ICP discharge tube. The plasma discharge tube has a three-layered structure made of quartz. A coil is wired on the top. A high-frequency magnetic field is induced by passing high-frequency current through the coil. If you add argon gas here, it will generate high-temperature plasma flame. Place the sample prepared a mist form by a nebulizer (atomizing device) onto a flow of argon gas. Once the gas has flown into the plasma flame, light emission occurs after vaporization, atomization, and excitation processes. Analyze this emission spectrum by the spectroscopic and photometry units.

[Fig.2] illustrates the analysis equipment system.

(3) Characteristics

The ICP emission spectrometric analysis can identify a lot more elements than the atomic absorption analysis. In addition to heavy metals, elements such as C (carbon), P (phosphorus), and S (sulfur) can be analyzed as well. Because this method is capable of analyzing multiple elements simultaneously in a single sample, it is used in a variety of fields, including food, textile, environment, and semiconductor industries in addition to steel and non-ferrous metal industry.