The fluorescence intensity of the samples was quantified using a Varian Cary Eclipse spectrofluorometer at excitation and emission wavelengths of 360 and 450 nm, respectively. Fig. 3(b) represents the increase in fluorescence intensity with the increase in the concentration of fluoride ion. This plot is based on readings taken from several replicates of fluoride samples. It can be observed from the figure that the fluorescence intensity linearly increases with fluoride concentration indicating a 1:1 stoichiometric ratio between fluoride ions and TBDPSC. It should be noted that no fluorescence is observed in samples with DI water (no fluoride ions).