To conduct in-situ rapid detection of benzene in groundwater in chemical parks, the design and experimental research of fluorescence detection are carried out.

First, we design a fluorescence excitation and collection optical system, obtain fluorescence spectroscopy of benzene series by three-dimensional fluorescence spectroscopy, and then select optical components (Figs. 1?5). The optical system adopts the excitation-collection orthogonal mode, in which the fluorescence excitation light path adopts a converging collimated beam to reduce emission angles in excitation regions and stray light interference, and the fluorescence receiving light path adopts a three-piece lens to reduce structure size and improve the energy reception efficiency (Figs. 6?8). We further design a fluorescence signal acquisition system and arrange the core circuit modularly. We also design an end-window mechanical structure and a cylindrical-shaped sealed cabin for the experimental system to protect the internal photoelectric system, efficiently completing the fluorescence collection, analysis, results storage, and data transmission for benzene series in groundwater (Figs. 9?11). On this basis, we employ the standard addition method to prepare benzene samples and use groundwater from chemical parks in Jiangxi Province for testing with our experimental system (Table 1).

The experimental results show a linear relationship between the concentration of the samples under measurement and the fluorescence signal intensity. The correlation coefficient is above 0.9634, and the detection limit is less than 0.26 mg·L^-1; the average relative error remains below 9.3%, the stability is less than 0.08, and the repeatability is below 7.5%. The accuracy is close to the test result of the Hitachi F-7000 fluorescence spectrometer (Figs. 12 and 13,Tables 2?4).

The results show that the experimental system has high accuracy, strong stability, and good repeatability, and it is suitable for the rapid detection of benzene series in groundwater in chemical parks.