Internal multiple interactions-adsorption and external zwitterionic polymer-exclusion of restricted access materials as adsorbent for offline and online extraction of neonicotinoid pesticides in Goji samples.

A method based on novel restricted access materials (RAMs) for the determination of neonicotinoid pesticides in Goji samples using offline and online solid phase extraction (SPE) coupled with high-performance liquid chromatography (LC). RAMs were synthesized using poly(chloromethylstyrene-co-divinylbenzene) (P) microspheres as substrate, styrene (St) and n-vinylpyrrolidone (NVP) were first copolymerized on the interior to construct adsorption sites, and sulfobetaine methacrylate (SBMA) was then polymerized on the exterior to form exclusion sites via two-step surface initiated-atom transfer polymerization. The prepared P@poly(St-co-NVP)@poly(SBMA) RAMs could efficiently extract neonicotinoid pesticides and automatically exclude proteins.

Triblock copolymer-grafted restricted access materials with zwitterionic polymer outer layers for highly efficient extraction of fluoroquinolones and exclusion of proteins.

High-selectivity and high-exclusion restricted access materials (RAMs) benefit the analysis of biological samples. Herein, triblock copolymer-functionalized poly(4-vinylbenzyl chloride-co-divinylbenzene) (P) microspheres were prepared via the sequential surface-initiated atom radical polymerization of hydrophobic styrene (St), ionic vinylimidazole (VIm), and zwitterionic sulfobetaine methacrylate (SBMA), affording RAMs with multiple interaction-adsorption sites and zwitterionic polymer exclusion sites on the internal and external surfaces of P. The preferential extraction of fluoroquinolones (FQs) is realized based on the hydrophobic/π-π/ion exchange interactions due to the grafted poly-St-VIm, and the zwitterionic poly-SBMA block in the triblock copolymers can efficiently exclude various proteins.

[Ligand exchange chromatographic separation of DL-amino acids based on monodisperse resin-bonded chiral stationary phase].

L-Proline chiral stationary phase for ligand exchange chromatography was prepared in the following steps. First, the particles were completely hydrolyzed. Second, the hydrolyzed particles reacted with epichlorhydrin to obtain chlorinated beads.

[Preparation of weak cation-exchange packings based on monodisperse porous poly (chloromethylstyrene-co-divinylbenzene) beads and its applications in separation of biopolymers].

Monodisperse polystyrene seed particles were prepared by dispersion polymerization of styrene in ethanol and water under a nitrogen atmosphere using benzoyl peroxide as an initiator. Then the monodisperse, porous poly (chloromethylstyrene-co-divinylbenzene) beads in the range of 6 - 15 microm were prepared by one-step swelling and polymerization method. Based on this media, a new hydrophilic weak cation exchange stationary phase (WCX) for high performance liquid chromatography was synthesized by a new chemical modification method.