This study showed that using the atom, ion, and a combination of atom and ion lines of only two elements as internal standards, it was possible to obtain very good results on a wide variety of elements in different matrices The samples were mixed into a rubidium chloride-graphite medium and burned to completion in a dc arc using a Stallwood jet. Analysis of the results, carried out on twelve elements in six matrices, showed that in 55 out of 70 cases an accuracy of better than 15% was attained (29 of these were within 5%). Both major and minor components were determined on the same spectrogram. Elements included Na, Al, Ba, Ca, Fe, Mg, Mn, Pb, Si, Sn, Zn, and Zr with indium and lutetium used as the internal standards.
P. Tymchuk, D. S. Russell, and S. S. Berman, "The Use of a Combination of Atom and Ion Lines as Internal Standards in General Spectrochemical Analysis," Appl. Spectrosc. 17, 163-165 (1963)