Construction And Application Of Online Determination Platform Composed By Microfluidic Enrichment,Separation And Electrospray Ionization Modules

In biochemical determinations,sample pretreatment was usually needed due to the limited sample volume and low contents of target chemicals.Reported methods were conventionally based on SPE and zip-tip to achieve sample enrichments.Those methods showed advantages in low sample consumptions,while they were complicated in experimental procedures.Moreover,satisfactory detectors which provided good sensitivity and resolution,were either crucial to accomplish accurate analysis for samples.Therefore,researchers proposed online extraction,separation and mass spectrometry detection for samples by integrating multiple functional units in microfluidic chips,and in this way,all requirements in biochemical analysis were achieved.In addition,when compared to microfluidic micro-manufacturing technology,3D printing technology was more simple and convenient.It could be used for fabrications for functional microfluidic chips.In this work,following studies were carried out based on proposed functional microfluidic chips and 3D printing technology.(1)In this part,extraction and separation modules were designed and fabricated by filling C18 silica particles into chips based on the wet packing method.Pesticide and its metabolites in the excrement of cotton bollworms were enriched based on the proposed extraction module,and PCR amplification products were either desalted.Separations of rhodamine B(RhB),reserpine,Juvenile Hormone III as well as standard pyridalyl solutions with different concentrations were taken based on the proposed separation module.After that,the pressure durability of the separation module was evaluated.Those results revealed a stable and reliable column efficiency,a decent quantitative and compressive capacity of the separation chip.(2)In addition,an online microfluidic electrospray module was designed and fabricated.It was coupled with preceding extraction,separation modules by a manual injection valve and HPLC.In this way,an online pretreatment,detection platform was thus achieved.Moreover,peptides and metabolites were desalted,enriched and determined based on the platform.By comparing the detection results of several online operations,performances of modules were confirmed,and the feasibility of the proposed detection platform was reviewed.(3)Separation chips were fabricated by the fusion deposition method based on 3D printing technology.C18 silica was filled into the separation chip using dry method in the process of printing,and this strategy would make obtained stationary phase more compact and uniform.Proposed separation modules were applied in determinations for RhB solution with different concentrations and a mixture containing four chemicals.In this way,the detection limit and recovery rate of each substance in the mixture were determined.Finally,the pressure durability of the separation chip was evaluated.Preceding evaluations revealed separation,quantification and pressure durability of the proposed 3D printing separation chip.