Inner filter effects and other traps in quantitative spectrofluorimetric measurements: Origins and methods of correction

Spectrofluorimetry is an analytical technique endowed with excellent versatility and high sensitivity. The low cost, handiness of use, and compact size of modern spectrofluorimeters has fostered their widespread availability in chemical laboratories. However, the utilization of spectrofluorimetry to determine concentrations - an essential task to investigate intermolecular association phenomena - is complicated by the non-linear instrument-dependent relationship between the concentration of the luminescent analyte and the detected emission signal, as well as by the spectrophotometric characteristics of the sample. Here we discuss the instrumental factors affecting the luminescence intensity observed in solution experiments with fixed excitation and emission wavelengths, and we propose a simple data correction method that converts the measured intensity value into a quantity which is linearly proportional to the concentration of the luminophore of interest. Two examples illustrating the method and its application for the study of self-assembly processes, taken from our research, will also be presented.