Mass Spectrometry And Liquid Chromatography Analysis Based On In-situ Microsampling

Ambient ionization mass spectrometry(MS)techniques,with the advantages of requiring little or no sample preparation,in-situ microsampling,and operating in the open air,have been widely used in MS imaging,proteomics,metabolomics and so on.With the rapid development of microfluidics and microfabrication technologies,it is capable of integrating multiple functional structures on single chip,including microsampling probes,mixers,and chemical separations.Therefore,there are great potentials to combine microfluidics with ambient ionization MS techniquesIn Chapter 1,the current progress of ambient ionization technique is reviewed.The main structures and principles of different ionization techniques is comprehensively described.Meanwhile,the main application fields of ambient ionization MS technique are also describedIn Chapter 2,we described microfluidic techniques can greatly simplify the setup and improve the performance of ambient MS by integrating sampling probe,electrospray emitter probe,and online mixer on single glass chip.Microfluidic teclrniques not only enhanced the capability of ambient MS methods in analysis of dry-spot samples on various surfaces,but also enabled new applications in the analysis of nanoliter-scale chemical reactions in an array of droplets.The versatility of the microchip-based ambient MS method was demonstrated in different applications including the evaluation of pesticide residual on fruit surfaces,sensitive analysis of low ionizable analytes using post-sampling derivatization,and high throughput screening of Ugi-type multi-component reactions.In Chapter 3,we developed in-situ high performance liquid chromatography(LC-MS)system based on a high pressure microsampling interface.The microsampling interface was fabricated with a coaxial capillary column and stainless steel tube,which were assembled through a tee.With this system,picogram-sized sample can be introduced from the surface of sample plate into the nanoLC column,followed by high resolution separation and MS detection.As a preliminary demonstration,the present system was applied to the separation and detection of 5 standard peptide mixtures.