In plasma emission spectroscopy, a sample solutiun is introduced into the core of inductively coupled argon plasma (ICP) at a temperature of approximately 9000C. At this temperature all elements become thermally excited and emit light at their characteristic wavelengths.
The technique is ideally suited for ultratrace elements in wide range of samples. We test about 60 elements in geochemical and other samples that digested in aqua regia or mixture of four acids.