Fig. 1. Structure diagram of sample dilution

Fig. 2. Structure diagram of the equipment

Fig. 3. UV absorption spectra of NaCl, NaOH and PEA at 0.001 49 mol·L^-1

Fig. 4. UV absorption spectra of the mixtures at seven different concentrations

Fig. 5. Distribution of score vector values in the space of the first three PCs

Fig. 6. Sample distribution of NaCl, NaOH and PEA in the plane of the discriminant functions

Fig. 7. Classification results of the mixture obtained by three supervised classification method
(a): RBF-SVM; (b): BP ANN; (c): ABC BP ANN; (a): RBF-SVM; (b): BP ANN; (c): ABC BP ANN; 1: 0%mol·L^-1; 2: 10%mol·L^-1; 3: 20%mol·L^-1; 4: 30%mol·L^-1; 5: 40%mol·L^-1, 6: 50%mol·L^-1; 7: 60%mol·L^-1