Principle : The spectrometry inductively-coupled plasma (or spectroscopy (icp) is a physical method of chemical analysis to determine the quasi-totality of the elements at the same time (the scan takes a few minutes, excluding preparation) due to the high power argon plasma (>8000°c).
the method involves ionizing the sample by injecting it in a plasma of argon or sometimes helium, that is to say that the atoms of matter to be analyzed are converted into ions by a kind of flame is extremely hot : up to 8 000 k, but in general around 6 000 k for applications in geochemistry. some devices, however, are equipped with an option called ” cold plasma “, which heat up to several hundred k all the same, allowing the analysis of organic molecules that would otherwise be destroyed.
the sample generally penetrates into the plasma in a condensed form (liquid or solid), and, therefore, must undergo changes of state : melting (for solids), vaporization, ionization. the introduction takes place in the center of the plasma, parallel to the flow of the plasma gas.
the sample must be introduced into the plasma in a form finely divided, for the powers used (typically less than 2 000 w of incident power) does not allow particles of a size greater than the micrometer during their residence time within the plasma ; if one wants to analyze a solid, it must therefore first be transformed into a suspension of fine particles, carried by a current of the plasma gas.