Polymeric Functionalized Stationary Phase for Separation of Ionic Compounds by IC

Influencing the selectivity of grafted anion exchangers utilizing the solubility of the radical initiator during the graft process

A previously published radical graft-functionalization method for the synthesis of high performance anion exchangers was further investigated to control the capacity and selectivity of the exchangers. Using a hydrophobic radical initiator instead of a hydrophilic one diminished the influence of rivaling homopolymerization of monomer during the functionalization step. Instead of only generating monomer radicals in free solution the radicals are ideally generated on top of the PS/DVB surface. However, in both cases the selectivity factors of polarizable anions bromide and nitrate in relation to chloride increased strongly with increasing capacity of the exchanger. Higher exchanger capacities could lead to coelution of bromide and/or nitrate with other analytes such as sulfate or phosphate when using the eluent as proposed in this work. By variation of the organic solvent used for functionalization it was possible to remove both the rivaling homopolymerization and the strong influence of the capacity on the selectivity. With increasing solubility of the hydrophobic radical initiator in the organic solvent the influence of the homopolymerization and the influence on the selectivity factor of bromide and nitrate decreased. Additionally, a change of bromate selectivity factor could be observed. The bromate signal is shifted closer towards the chloride signal. However, with increasing solubility of the radical initiator in the organic solvent the observed capacity of the exchangers decreases linearly, resulting in higher amounts of monomer needed for functionalization.

Synthesis and chromatographic evaluation of phenyl/tetrazole bonded stationary phase based on thiol-epoxy ring opening reaction

A silica-based reversed-phase stationary phase bonding with phenyl and tetrazole groups was synthesized by thiol-epoxy ring opening reaction. The bonded groups could not only provide hydrophobic interaction, but also π-π, hydrogen bonding, electrostatic interactions, and so on. The results of characterization with elemental analysis and solid-state ¹³ C cross-polarization magic-angle-spinning NMR spectroscopy indicated the successful preparation of phenyl/tetrazole sulfoether bonded stationary phase. Chromatographic evaluation revealed that phenyl/tetrazole sulfoether bonded stationary phase behaved well under the reversed-phase mode. The column parameters (H, S*, A, B, and C) showed different selectivity compared with some typical commercial columns, and it was validated by the separation of estrogen, ginsenoside, alkaloid samples. Based on the different selectivity between phenyl/tetrazole sulfoether bonded stationary phase and C18 columns, phenyl/tetrazole sulfoether bonded stationary phase also showed potential to construct a 2D reversed-phase liquid chromatography system with C18. And it was verified by the separation of corydalis tuber and curcuma zedoary extracts.

Fabrication of graphene oxide polymer composite particles with grafted poly(amidoamine) dendrimers and their application in ion chromatography

Graphene oxide polymer composite particles with grafted PAMAM dendrimers and their application in ion chromatography.

Functionalized anion exchange stationary phase for separation of anionic compounds

Synthesis of the multilayered stationary phases containing quaternary ammonium functional groups on the silica support was described. Bonded phases were characterized by elemental analysis, solid state (13)C NMR spectroscopy and chromatographic methods. The surface of silica support was coated with different number of polymeric layers formed by condensation polymerization of primary amine (methylamine) with diepoxide (1,4-butanedioldiglycidyl ether). A series of stationary phases with different number of polymerized layers were tested. Separation of an inorganic anions sample (F(-), Cl(-), NO2(-), Br(-), NO3(-)) and nucleotides was performed.