The cmc in water + EG media in the presence of NaCl AG 99 also determined by the fluorescence technique using pyrene as the probe. The representative plots of I1/I3 ratio of pyrene as a function of SDS concentration in 10% EG + water containing different amounts of NaCl are shown in Fig. 4 and similar plots in 30 and 50% EG + water are shown in Figs. S15 and S16. I1 and I3 refer to the intensities of the fluorescence emission spectra of pyrene at 374 and 384 nm, respectively. Applying the method of Aguiar et al.  to estimate cmc, we fitted the I1/I3 data to the sigmoidal equationequation(2)I1/I3=A2+ (A1−A2)/[1+exp((cs–x0)/b0)] I1/I3=A2+A1−A2/1+expcs–x0/b0where cs represents SDS concentration, x0 is the value of cs corresponding to the center of the sigmoid, A1 and A2 are the upper and lower limits of the sigmoid, respectively, and b0 is a term birth rate reflects the range of cs where sudden change in I1/I3 occurs. The values of the parameters of Eq. (2) obtained from the fitting are listed in Tables S6 and S7 and the value of x0 is taken as cmc. The cmc values determined using pyrene probe becomes less reliable as the content of EG in the mixed solvent becomes 50% or more due to enhanced solubility of pyrene in the bulk.