Inductively coupled plasma atomic emission spectrometry (ICP-AES) is a type of spectroscopic analysis method that uses inductively coupled plasma torches as the excitation light source. It is a new type of analysis technique derived from atomic emission spectroscopy. It can easily, quickly and accurately determine a variety of metal elements and metalloid elements in water samples without significant matrix effects. Today ICP-AES analysis technology has become an important part of modern detection technology.
Principle of ICP-AES method
Plasma emission spectroscopy can simultaneously determine the content of multiple elements in a sample. When the argon gas passes through the plasma torch, the alternating electromagnetic field generated by the radio frequency generator ionizes, accelerates and collides with other argon atoms. This chain reaction ionizes more argon atoms, forming a particle mixture of atoms, ions, and electrons, that is, plasma. Atoms of different elements can emit characteristic spectra when excited or ionized, so plasma emission spectroscopy can be used to qualitatively determine the elements present in the sample. The strength of the characteristic spectrum has nothing to do with the concentration of atoms in the sample. By comparing with the standard solution, the content of each element in the sample can be quantitatively determined.
Advantages and disadvantages of ICP-AES method
Compared with other methods, the ICP-AES method has the following advantages:
(1) Fast analysis speed. The ICP-AES method has low interference, stable time distribution, and wide linear range. It can read the characteristic spectra of multiple measured elements at the same time, and perform quantitative and qualitative analysis of multiple elements at the same time.
(2) High analytical sensitivity. For direct spectrograph measurement, the relative sensitivity is generally 10-6; the absolute sensitivity is 10-3-10-9 g. If it is enriched, the relative sensitivity can reach 10-9 level, and the absolute sensitivity can reach 10-11g.
(3) The analysis accuracy and precision are high. The ICP-AES method is the one with less interference among various analytical methods. In general, its relative standard deviation is less than 10%. When the analyte concentration exceeds 100 times the detection limit, the relative standard deviation is less than 1%.
(4) Wide measuring range. It can measure almost all spectral lines in the ultraviolet and visible regions, and the range of measured elements is large, and dozens of elements can be measured at a time.
The disadvantage of the ICP-AES method is that the equipment and operating costs are relatively high. The sample generally needs to be converted into a solution in advance (the precision and accuracy are reduced when the solid is directly injected), and the advantages of some elements are not obvious.
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