EELS can be used for elemental analysis since the edges occur at the energy losses corresponding to the binding energies of the core electrons in the elements, and the integrated intensity under the edge depends on the number of atoms penetrated by the incident electron beam. Different from EDS, EELS can provide elemental data on all the light elements except H and He, although the latter had been detected under certain conditions, e.g., in nanometer-sized He bubbles in irradiated Ni alloys [1].

Fundamental limitations of EELS for the detectability are:
       i) For trace elements, the large pre-edge background is the main factor.
       ii) For some TEM samples, beam damage is the main factor.