One-pot Facile Preparation of Amino-functionalized Silica Hybrid Monoliths for Mixed-mode Chromatography

Abstract

Silica hybrid monolithic columns were prepared using two precursors, in which organo-functionalized trialkoxysilanes are mixed with tetraalkoxysilanes. In this study, several types of amino-functionalized silica hybrid monolithic columns were prepared via single-step "one-pot" approach, and the amount of silica precursors, porogens, as well as the reaction conditions were optimized. The preparation was carried out by mixing the silica precursors, i.e. tetraethoxysilane (TEOS) or tetramethoxysilane (TMOS) with amino precursors such as aminopropyltrimethoxysilane (APTES), aminoethylaminopropyl-trimethoxysilane (AEAPTMS), and phenylaminopropyltrimethoxysilane (PAPTMS) in a porogenic solution. The chromatographic performance of these hybrid monolithic columns was optimized by investigating several parameters through the separation of inorganic anions (IO3 -, BrO3 -, Br -, NO2 -, NO3 -, I -, SCN -) and some polar compounds (thymine, thymidine, adenosine, adenine, uridine). Results showed that the silica hybrid monolithic columns could be operated at higher flow-rate that favors rapid separation. The run-to-run repeatability of Si-APTES and Si-PAPTMS hybrid monolithic columns were satisfactory with relative standard deviations (n = 5) of less than 8% for all the analyte anions.Amino-functionalized silica precursors was used in the preparation of hybrid monolithic column to reduce the preparation time via one-pot approach. The amine groups in the structure can provide weak anion exchange interaction and also hydrophilic interaction. The synthesized hybrid monolithic columns revealed good mechanical stability and good separation repeatability.

Chitosan-Functionalized Methacrylate Monoliths for Mixed-Mode Hydrophilic/Electrostatic Interaction Capillary Liquid Chromatography

“…The inorganic silica monoliths exhibit homogeneous skeletons and large surface areas with adequate separation performance for small molecules. However, the poor stability at pH out of the 4–11 range is a significant disadvantage of silica-based monoliths. , The organic polymer monoliths are usually prepared by conventional chain-growth polymerization (via free radical polymerization (FPR)) of vinyl monomers and cross-linkers. The organic polymer serves heterogeneous interconnected large through-pores between aggregated microglobules with good mechanical and chemical stability and hydrophobic surface.…”

Separation of Inorganic Anions Using an 18-Crown-6-ether-modified Organic Polymer Monolithic Stationary Phase in Capillary Ion Chromatography

“…On the other hand, an organic polymer-type monolith is prepared by reacting a solution comprising a copolymerized monomer, a crosslinking agent, a pore-forming agent ("porogen"), and a polymerization initiator in the same type of column. [14][15][16][17][18][19][20] The organic polymer-type monolithic column is easier to prepared and it displays excellent pH durability; as such, irreversible adsorption rarely occurs.…”