Study On Structure Optimization And Application Of Ion Mobility Spectrometry

As people’s concern for their health increases,so does the concern for a green environment and food safety.The development of testing instruments and the innovation of testing techniques are significant for protecting human health.Ion mobility spectrometry(IMS)stands out among analytical instruments because of its simple overall structure,high sensitivity,and fast analysis.In this thesis,a variety of migration tube structures are designed to address the problems of low sensitivity and blind areas in the detection of ultra-low concentration substances in DAPI-TRTD-IMS,the main research work is as follows:(1)Design and analysis of optimized drift tube structure of ion mobility spectrometer.The drift tube structure is designed and optimized,a simplified drift tube structure model is established,and the influence of the drift tube structure parameters on the flow velocity and density of the internal flow field is studied.The optimum drift tube structure parameters were obtained by analyzing velocity,density,radial velocity,and radial temperature uniformity factors.The results show that the average velocity in the reaction zone increases with the increase of the aperture diameter.The lowest average velocity value in the reaction zone was obtained for model 4 at the same pore size.The density of the reaction zone increases and then decreases as the pore size increases,peaking at a pore size of 3 mm.In the drift zone,the stability and fluctuation of radial velocity and temperature in the three parts of the drift zone gradually decreased as the number of layers of the porous plate increased.The ion mobility spectrometer has the optimal sensitivity and resolution when the reaction zone is model 4,the pore size is 3 mm,and the drift zone has a three-layer porous plate structure.(2)Optimal design and analysis of the ion mobility spectrometer tube connector structure.To build a two-dimensional MCC-IMS experimental platform,we designed a tube joint connection component to link the MCC and IMS successfully.The rationality of the tube fitting design was verified through finite element analysis,and the performance of the tube fitting with different preload forces for different materials was studied.The optimal structural parameters of the tube fitting were obtained by analyzing factors such as stress strain and deformation.The research results show that the tube joints made of stainless steel can generally be used under the preload force not exceeding 3 KN,which meets the working environment of MCC-IMS coupling and the performance requirements of the tube joints.(3)Experimental validation of ion mobility spectrometer structure optimization.By detecting the standard concentration samples of toxic and hazardous substances produced by shrimp spoilage,the detection performance of DAPI-TRTD-IMS coupled with MCC after optimizing the drift tube structure was verified.The results showed that the sensitivity and resolution of the MCC-IMS instrument were significantly improved after drift tube optimization.The peak intensities of ammonia and trimethylamine detected by the IMS before drift tube structure optimization were all lower than those of the DAPI-TRTD-IMS after structure optimization,and the sensitivity of the DAPI-TRTD-IMS after structure optimization was increased by 160%,and the detection range was expanded.The results of this experiment validate the improved performance of the drift tube optimized DAPI-TRTDIMS and demonstrate the potential of MCC-IMS for the qualitative and quantitative determination of the freshness of shrimp.The ability of the MCC-IMS to detect shrimp top air 12 hours after death was demonstrated in the field in the context of complex matrices.