This method covers the analysis of copper base alloys for aluminum, lead, and tin (0.30 to 15.0 percent); iron, manganese, beryllium, and nickel (0.30 to 5.0 percent); and zinc (0.30 to 40.0 percent). Samples are taken into solution with a mixture of nitric and hydrofluoric or nitric and hydrochloric acids. The volume is adjusted so that the concentration of the alloy is 50.0 mg/ml. A portion of this solution is mixed with 19 parts of copper nitrate solution (copper = 50 mg/ml). Spectra are obtained of aliquots of each sample and of a series of standard solutions dried on porous graphite electrodes and excited in the d.c. arc. Determinations of the amounts of constituent elements present in the samples are made by measuring the ratio of intensities of a line of the constituent element to that of a copper control line, by the general internal standard procedure.
EDWIN K. JAYCOX, "The Spectrochemical Analysis of Copper Base Alloys," J. Opt. Soc. Am. 35, 175-176 (1945)