| In-situ fluorescence spectroscopy is very important for the determination of trace impurities in industrial production and safe production.At present,the chemical reaction system has complex components and a fast flow rate.Existing commercial fluorescent instruments have limitations such as small detection temperature range,narrow field of view,and off-line detection.They are not suitable for reaction process research and cannot meet the detection requirements of the existing chemical industry.Based on this,this paper proposes a method for simultaneous analysis of ultraviolet spectroscopy and fluorescence spectroscopy.Meanwhile,designed and built a new online in-situ fluorescence analyzer.The test samples under different p H and temperature and the appropriate reaction system were selected to verify the real-time online monitoring function of the instrument.This realized the online in-situ detection of chemical reaction process,which has important supporting significance for industrial production.The main research progress is as follows:(1)The design idea of synchronous analysis of ultraviolet spectrum and fluorescence spectrum was proposed.The overall layout of the instrument was planned.A high-quality,tunable point laser was used as the excitation light source to excite the liquid phase reaction system.The wavelength and intensity changes of the fluorescence emission spectrum can be detected online.Accurate in-situ detection of the dynamic changes of the structure and concentration of reactants,products,catalysts,etc.in the reaction system.And the transient ultraviolet absorption and fluorescence emission spectra of the reaction system can be obtained in real-time and quickly.It can analyze deeply the transformation of the material structure in the reaction system,provide data support for mechanism research and online control of chemical reaction processes.(2)Completed the construction of the in-situ fluorescence analyzer.According to the principle of combining safety and precise testing,modules such as ultraviolet excitation light source,OPO optical parametric oscillator,designable light path,in-situ reaction cell,fiber optic spectrometer,temperature control instrument,data processing system were designed and assembled.Different concentrations of rhodamine B solution and potassium chromate solution were used to verify the basic detection functions of the UV absorption spectrum and fluorescence spectrum of the in-situ fluorescence analyzer.(3)The applicability of the in-situ fluorescence analyzer for in-situ online monitoring of the chemical reaction process was verified.Real-time online monitoring of 0.156 g/L fluorescein isothiocyanate(FITC)ethanol solution under different acidity to obtain UV and fluorescence spectrum.The intensity of the fluorescence peak at480～700 nm increased gradually when p H = 3.0～10.0,and the intensity of the characteristic fluorescence peak decreased gradually when p H >10.0,under the 355 nm laser.The UV absorption peak intensity of the FITC solution increased gradually with the increase of p H.The UV-fluorescence spectrum of Rhodamine B acetonitrile solution was monitored during the temperature change.The intensity of the characteristic fluorescence peak increases gradually at 580 ～ 740 nm with the decrease of temperature.This shows the device can complete in-situ fluorescence detection of samples under changing conditions.The preparation process of benzimidazole was further analyzed by in-situ fluorescence.The results show the fluorometer can detect the concentration and structure changes of the reaction substrates and products online during the chemical reaction process.Based on the above results,the detection sensitivity of the in-situ fluorescence analyzer developed in this paper is relatively high.It can accurately capture real-time changes of the UV spectrum and fluorescence spectrum caused by p H and temperature changes.It can lay the foundation for in-situ online real-time monitoring of chemical reaction processes with fluorescence changes. |
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