The sources of error in the application of the ponderal ratios in flame photometry were calculated from the results of the analysis of solutions containing copper and zinc. Deviations during calculations cause differences in the equations of the correction curves. These differences permit deriving equations for calculating variation of the correction factors and calculated concentrations. The deviations found in the calculated concentrations by the ponderal ratios method are much smaller than those usually found in flame-photometric work.
J. Ramírez-Muñoz, A. Carrillo-García, Y. Díaz-Hernández, and H. Tavera-Beltrán, "A Study of the Sources of Errors in the Application of the Ponderal Ratios Method in Flame Photometry," Appl. Spectrosc. 18, 69-71 (1964)