Minjie Hu

Ampholine-functionalized hybrid organic-inorganic silica material as sorbent for solid-phase extraction of acidic and basic compounds.

A novel sorbent for solid-phase extraction (SPE) was synthesized by chemical immobilization of ampholine on hybrid organic-inorganic silica material. The ampholine-functionalized hybrid organic-inorganic silica sorbent is consisted of aliphatic amine groups, carboxyl groups and long carbon chains, allowing for extraction of both acidic and basic compounds. The retention properties of the developed sorbent were evaluated for 1-hydroxy-2-naphthoic acid (HNA), 1-naphthoic acid (NA), 3-hydroxybenzoic acid (HBA), benzoic acid (BA), sorbic acid (SA), vanillic aldehyde (VA), butyl 4-hydroxybenzoate (BHB), propyl 4-hydroxybenzoate (PHB), ethyl 4-hydroxybenzoate (EHB), and methyl 4-hydroxybenzoate (MHB). The results show that such a sorbent has three types of interaction, i.e., electrostatic interaction, hydrophobic interaction, and hydrogen bonding, exhibiting high extraction efficiency towards the compounds tested. The adsorption capacities of the analytes ranged from 0.61 to 6.54μgmg(-1). The reproducibility of the sorbent preparation was evaluated at three spiking concentration levels, with relative standard deviations (RSDs) of 1.0-10.5%. The recoveries of ten acidic and basic compounds spiked in beverage Coca-Cola(®) sample ranged from 82.5% to 98.2% with RSDs less than 5.8%. Under optimum conditions, the ampholine-functionalized hybrid organic-inorganic silica sorbent rendered higher extraction efficiency for acidic compounds than that of the commercially available ampholine-functionalized silica particles, and was comparable to that of the commercial Oasis WAX and Oasis WCX.

Synthesis and Characterization of Copolymerized Vinyl/phenylsilsesquioxane Microspheres

Copolymerized vinyl/phenylsilsesquioxane microspheres were prepared by the sol-gel polymerization method from phenyltrimethoxysilane (PTMS) and vinyltrimethoxysilane (VTMS). The microsphere size was from 0.8 μm to 2.7 μm. Effects of the reaction parameters, such as NH4OH concentration, the ratio of oil to water (O/W) and monomer ratio on microsphere size, shape and distribution were investigated. The results indicate that the preferred preparation conditions are NH4OH concentration in 0.02 ∼ 1.28 wt%, ratio of O/W from 1/3 to 1/50 in hydrolytic co-condensation reaction. With the increasing of NH4OH concentration and PTMS/VTMS ratio and decreasing of O/W ratio, the microsphere size is decreased. Finally, FT-IR measurement was used to characterize the structure of the copolymerized vinyl/phenylsilsesquioxane microspheres.

Copolymerization of norbornene, styrene, and naleic anhydride catalyzed by Fe(acac)3−Al(i-Bu)3

Copolymerization of norbornene (NB), styrene (ST), and maleic anhydride (MA) catalyzed by Fe(acac)3-Al(i-Bu)3 has been investigated at different conditions and Fe/Al ratios in the catalyst. The copolymer composition has been investigated by using 13C NMR, FTIR, and gel permeation chromatography. Results demonstrate that the Fe(acac)3-Al(i-Bu)3 catalysts are effective for the copolymerization of NB, ST, and MA at mild conditions.