Study On The Application Of Core-shell SiO₂@SiO₂ Microspheres In Traditional HPLC

From the very beginning of its establishment,high performance liquid chromatography（HPLC）has been dedicated to achieving a fast and efficient separation.The stationary phase matrix has been updated all the time since last century.It is the core-shell particles that is the hot research topic at present.As the fifth separation media,the reason why shell particles have drawn widespread attention lies not in the absolute replacement of these traditional materials but a well combination of the merits of non-porous silica as well as the fully porous particles.The inner part of the materials consists of a solid non-porous core which endows the particles a good thermal conductivity as well as a better robustness,while the outer part,a porous shell structure,ensures this media a certain porosity and sample capacity,and can accelerate the mass transfer rate of solutes by shorting the mass transfer path to achieve a fast separation.In recent years,the use of sub-2μm core-shell particles in ultra-high performance liquid chromatography（UHPLC）has extensively renewed the fast separation record.There’s no denying,though,that it is still a huge task to perform a fast separation with core-shell particles on the traditional liquid chromatography.As a result,the core-shell technique is here combined with the fast separation media,i.e.,the chromatographic cake,whose backpressure is very low owning to the much longer inner diameter than its column length,to conduct efficient and fast separation of proteins in traditional HPLC.The article is divided into the following four parts:1.Literature review The basic principles and practical applications of various fast HPLC technologies,including sub-2μm non-porous particles,sub-2μm fully porous particles,core-shell technology as well as the chromatographic cake technology were overviewed in this part.Both the advantages and disadvantages of each technology were discussed thoroughly.2.The preparation of monodisperse SiO₂@SiO₂ core-shell microspheres In this part,the synthesis of core-shell microspheres is briefly introduced.Monodisperse SiO₂@SiO₂ core-shell microspheres were prepared by PICA method based on the previous work of our group.The condition of the preparation and the modification of non-porous silica as well as the controllable preparation of core-shell particles were further optimized.Various characterization of the synthesized shell particles including SEM,TEM,BET and N₂adsorption shows that monodisperse SiO₂@SiO₂ core-shell microspheres with desired morphology as well as a proper pore size were prepared successfully.3.Application of SiO₂@SiO₂ core-shell microspheres in reversed phase chromatography Based on the short column theory of protein separation,C18 modified core-shell particles with particle size of 2.3μm or 2.9μm and 4.4μm were first packed into various chromatographic columns with different column lengths for the separation of standard proteins.Owing to the limited pressure tolerance range of traditional chromatograph,the above three kinds of particle size shell particles were further packed into different kinds of chromatographic cake to conduct a fast separation of proteins.The results showed that the core-shell particles could also be used in traditional HPLC with a flow rate of 8 ml/min and can achieve a baseline separation of seven protein mixtures within 2.5 min.4.Application of SiO₂@SiO₂ core-shell microspheres in hydrophobic chromatographic mode and hydrophilic chromatographic mode The Si O₂@SiO₂ core-shell microspheres were modified by PEG-600 andδ-gluconolactone and further packed into chromatographic cake to perform a fast separation of proteins in HIC mode and HILIC mode.It shows that 8 kinds of proteins can be separated with cake under within 1 min in HIC mode;the separation of the proteins in HILIC mode is also good and can be further optimized.