Effect of Hydrophobic Moieties on the Assembly of Silica Particles into Colloidal Crystals.

To boost the implementation of colloidal crystals (CCs) in separation science, the effects of the most common chromatographic reversed phases, that is, butyl and octadecyl, on the assembly of silica particles into CCs and on the optical properties of CCs are investigated. Interestingly, particle surface modification can cause phase separation during sedimentation because the assembly is highly sensitive to minute changes in surface characteristics. Solvent-induced surface charge generation through acid-base interactions of acidic residual silanol groups with the solvent is enough to promote colloidal crystallization of modified silica particles.

Preparation of open tubular capillary column covalently coated with polystyrene sulfonate with 4,4'-Azobis(4-cyanopentanoyl chloride) as polymerization initiator for electrochromatographic separation of alkaloids, sulfonamides, and peptides.

An open tubular capillary electrochromatography column covalently bonded with polystyrene sulfonate was prepared via in situ polymerization using functionalized Azo-initiator 4,4'-Azobis(4-cyanopentanoyl chloride). Scanning electron, fluorescence, and atomic force microscopy techniques showed the formation of a relatively rough layer of polymer. In addition, -CN and C = O stretching vibrations from infrared spectroscopy proved the successful immobilization of the azo-initiator through covalent bonding and X-ray photoelectron spectroscopy confirmed the elemental composition of the formed polymer layer.

[Novel submicron nonporous silica material modification with high carbon content and its application in reversed-phase pressurized capillary electrochromatography].

Submicron nonporous silica (NPS) materials feature small particle sizes, smooth surfaces, and regular shapes. They also exhibit excellent performance as a stationary phase; however, their use is limited by their low specific surface area and low phase ratio. Therefore, a novel surface modification strategy tailored for NPS microspheres was designed, involving a multi-step reaction.