Preparation Of Multifunctional Separation Media And Their Applications

Separation science is a very important research area in natural science. With the rapid development of food science, biomedicine, environmental science, chemical industry, separation and purication of these relevant target analytes put forward higher requirements. Recent years, a variety of separation and purication methods has been developed. As a kind of classical sepration method, high performance liquid chromatography (HPLC) is an important choice for separation of various compounds. On aspects of sample purification, magnetic solid phase extraction (MSPE) is simple, fast, and efficient compared to traditional solid phase extraction (SPE), and has been developed fast in recent years.Undoubtedly, the core of these separation methods is separation media. In order to improve their separation performance, preparation of multifunctional separation media has been the most dynamic work in separation science. Because of the diversity and complexity of the practical sample, new multifunctional separation media must be designed to meet the needs of practical sample analysis. The synthetic materials should have excellent stability and reproducibility, and high selectivity towards target analytes. Corresponding synthetic methods should be simple, fast, economic and environmentally friendly.In this dissertation, we developed some new synthetic methods for separation media. The proposed methods were demonstrated as simple, universal, and with good reproducibility. Based on these methods, we prepared some new multifunctional separation media, including one mixed-mode HPLC packings, two mixed-mode capillary monolithic stationary phases, and two magnetic materials. We also applied these materials to the separation of various analytes. Good separation performances were achieved using these materials, demonstrating their excellent application potential. The major contents of the dissertation include the following aspects.1. A new RAFT/click chemistry tandem grafting strategy was developed to prepare the polymer-grafting silica stationary phase. A novel polystyrene grafted silica stationary phase with embedded amide group was prepared based on this strategy, demonstrating reversed-phase (RP)/anionic exchange (AEX) mixed-mode retention mechanism towards benzoic acid and its analogs. Compared to commercial octadecyl bonded silica (ODS) column, the prepared stationary phase exhibitd less exposed silanols and better stability with pure water as mobile phase.2. NBu4SiW11O39(SiCH=CH2)2, a kind of organic-incorporated polyoxometalates (POM), was employed as a new monomer to be incorporated into the monolithic poly(butyl methacrylate-co-ethylene glycol dimethacrylate) capillary columns. Hydrophobic, strong cationic exchange (SCX), and H-bond interaction of the resultant POM-incorporated monolith towards analytes were confirmed by testing a series of chromatographic probes, and the column efficiency got apparently improved. The POM-incorporated monolith was employed for separation of 4 PAH isomers,5 nucleobases, and 6 neurotransmitters. And much better resolution can be achieved compared to the monolith without POM.3. A newly improved one-pot method, based on "thiol-ene" Click chemistry and sol-gel approach in microemulsion system, was developed for the preparation of Cg/PO(OH)2-silica hybrid monolithic capillary column. The prepared stationary phase demonstrated RP/cationic exchange (CEX) mixed-mode retention mechanism towards basic analytes on nano-liquid chromatography (nano-LC). On the basis of the developed nano-LC system with MS detector coupled to pipette tip solid phase extraction (PT-SPE) and derivatization process, we then realized quantitative determination of 6 endogenous GAs in only 5 mg rice leaves.4. A facile strategy for immobilization of organic-metal nanowires (OMNs) on Fe3O4 substrates was developed. This strategy was based on one-step solvothermal growth process of metal-glycerol precursor around substrates. By employing the proposed strategy, two types of metal-organic nanowires Titanium-glycerolate (TiGly) and Zirconium-glycerolate (ZrGly) were successfully immobilized on Fe3O4 nanoparticles. The prepared materials exhibited large specific surface area and excellent reproducibility. These newly fabricated Fe3O4@TiGly and Fe3O4@ZrGly were applied for fast and selective enrichment of ribonucleosides and phosphopeptides from biological samples. Our results showed that Fe3O4@ZrGly can selectively capture ribonucleosides with higher recovery as compared to Fe3O4@TiGly, while Fe3O4@TiGly exhibited higher selectivity towards phosphopeptides than Fe3O4@ZrGly.