AbstractThe theoretical relationships between fluorescence intensity and concentration have been used for the calculation of correction constants of the Lachance‐‐Traill and Rasberry‐‐Heinrich equation for systems of solutions. The constants have also been calculated by means of the multivariate least‐‐squares method. Those two alternatives have been tested on systems of Cu‐‐Fe‐‐Zn and Cu‐‐Fe‐‐Zn‐‐Pb in 3.5% aqueous nitric acid and compared with the simple two‐variable linear relationship between fluorescence intensity and concentration. The multivariate least‐‐squares alternative gives for the Lachance‐‐Traill method very accurate results (average relative deviation does not exceed 0.18%). In a theoretical discussion, the relationship between optimum sample concentration and solvent correction (enhancement) constant is shown. The optimum conditions for