Fig. 1. Experimental system design

Fig. 2. Three-dimensional fluorescent spectra of eight monoaromatic hydrocarbons. (a) Benzene, 1 mg·L^-1; (b) toluene, 100 μg·L^-1; (c) ethylbenzene, 1 mg·L^-1; (d) o-xylene, 2 mg·L^-1; (e) m-xylene, 500 μg·L^-1; (f) p-xylene, 500 μg·L^-1; (g) styrene, 500 μg·L^-1

Fig. 3. Appearance and its spectral curve of 255 nm UV light source. (a) Appearance; (b) spectral curve

Fig. 4. Hamamatsu H10721-210 and its response characteristic curve. (a) Appearance; (b) response characteristic curve

Fig. 5. Transmission curves of filter. (a) 255 nm filter; (b) LED with 255 nm filter; (c) 292 nm filter

Fig. 6. Fluorescence excitation-collection orthogonal light path

Fig. 7. Fluorescence excitation light path

Fig. 8. Fluorescence reception light path

Fig. 9. Physical diagrams of fluorescence signal detection circuits

Fig. 10. Experimental system

Fig. 11. Linear relationship between fluorescence signal and mass concentration of seven benzene series. (a) Benzene; (b) toluene,

Fig. 12. Fluorescence values of seven benzene series test samples. (a) Benzene; (b) toluene; (c) ethylbenzene; (d) o-xylene; (e) m-xylene; (f) p-xylene; (g) styrene