Inductively coupled plasma ionization

Inductively coupled plasma (ICP) is an ion source that is used in elemental (metal) analysis. Typical applications can be, among others, toxicological analysis (revealing metal poisoning) and environmental analysis (revealing metal pollution). 

Through a spark, electrons are generated and accelerated within the coil. The acceleration is caused by a high-frequency oscillating field, through a radio frequency (RF) current in the coil. Collision of the high-velocity electrons with argon forces ionization and production of an electron (Ar — Ar 4-e ). TTiis process creates heat with a typical temperature of the plasma of approximately 10 000 K. 

At this temperature, sample molecules enter the gas phase and are atomized. The atoms are ionized simply through the loss of an electron, producing singly positive charged species. The outer part of the plasma is cooled by an extra Ar flow to prevent the tube from melting. 

Since the nature of the ICP is such that analytes are atomized and ionized, typical spectra consist of only the single elements (metals). Examples of metals that can be determined by ICP-MS are Ag, As, Au, Ba, Be, Bi, Ca, Cd, Co, Cr, Cs, Cu, Li, Mg, 

and Zn. The detected m/z value in the mass spectrum corresponds to the isotope masses of the elements, and can be used as such for qualitative purposes, while the intensity is related to the concentration. Detection limits vary from parts per trillion to parts per billion. 

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Accurate, precise isotope ratio measurements are important in a wide variety of applications, including dating, examination of environmental samples, and studies on drug metabolism. The degree of accuracy and precision required necessitates the use of special isotope mass spectrometers, which mostly use thermal ionization or inductively coupled plasma ionization, often together with multiple ion collectors. 

The dominating method of ion formation in metabolic flux analysis is electron impact. It might be supplemented in the future by novel methods, such as matrix assisted laser desorption and electrospray. Additional techniques such as chemical ionization, fast atom bombardment or inductively coupled plasma ionization are only of minor importance and not further discussed in this context. 

Laser ablation and inductively coupled plasma ionization... 

Figure 2.5 Dependence of ionization degree a on first ionization energy Et of chemical elements by inductively coupled plasma ionization.

FAAS atomic absorption spectrometry with flame atomization, ICP-OES atomic emission spectrometry with inductively coupled plasma excitation, GF-AAS atomic absorption spectrometry with graphite furnace atomization, ICP-MS mass spectrometry with inductively coupled plasma ionization... 

The main purpose of the detector in a field-flow fractionation (FFF) system is to quantitatively determine particle number, volume, or mass concentrations in the FFF size-sorted fractions. Consequently, a number, volume, or mass dependent size distribution of the sample can be derived from detection systems applied to FFF [e.g., (UV-Vis) fluorescence, refractive index, inductively coupled plasma ionization mass spectrometry (ICPMS)]. Further, on-line light scattering detectors can provide additional size and molecular weight distributions of the sample. 

The mostly used interfaces in LC-MS are electrospray ionization, atmospheric pressure chemical ionization (APCI), atmospheric pressure photoionization (APPI), and inductively coupled plasma ionization (ICP). While ICP is mostly used in the determination of metals (for elemental analysis) and has its specific applications,... 

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