Preparation of boronic acid and carboxyl-modified molecularly imprinted polymer and application in a novel chromatography mediated hollow fiber membrane to selectively extract glucose from cellulose hydrolysis.

A novel boronic acid and carboxyl-modified glucose molecularly imprinted polymer were prepared through suspension polymerization, which is based on 1.0 mmol glucose as a template, 1.2 mmol methacrylamidophenylboronic acid, and 6.8 mmol methacrylic acids as monomers, 19 mmol ethyleneglycol dimethacrylate, and 1 mmol methylene-bis-acrylamide as crosslinkers. The prepared glucose-molecularly imprinted polymer had a particle size of 25-70 µm, and was thermally stable below 215°C, with a specific surface area of 174.82 m2/ g and average pore size of 9.48 nm. The best selectivity between glucose and fructose was 2.71 and the maximum adsorption capacity of glucose- molecularly imprinted polymer was up to 236.32 mg/ g which was consistent with the Langmuir adsorption model. The similar adsorption abilities in six successive runs and the good desorption rate (99.4%) verified glucose-molecularly imprinted polymer could be reused. It was successfully used for extracting glucose from cellulose hydrolysis. The adsorption amount of glucose was 2.61 mg/mL and selectivity between glucose and xylose reached 4.12. A newly established chromatography (glucose-molecularly imprinted polymer) mediated hollow fiber membrane method in time separated pure glucose from cellulose hydrolysates on a large scale, and purified glucose solution with a concentration of 3.84 mg/mL was obtained, which offered a feasible way for the industrial production of glucose from cellulose hydrolysates.

Preparation of a magnetic and recyclable superparamagnetic silica support with a boronic acid group for immobilizing Pd catalysts and its applications in Suzuki reactions.

Palladium is one of the best metal catalysts for Suzuki cross-coupling reaction to synthesize unsymmetrical biaryl compounds. However, homogeneous palladium (Pd) is limited in an industrial scale due to the high cost, separation, removal, and recovery issues. In this paper, a novel, high activity magnetic nanoparticles (Fe3O4@SiO2-APBA-Pd) catalyst was prepared by a simple, cost-effective procedure. The as-prepared functional nanoparticles (Fe3O4@SiO2-APBA) with boric acid group immobilized Pd through adding Pd(OAc)2 to Fe3O4@SiO2-APBA in absolute ethanol and maintaining for a certain time under a nitrogen atmosphere. The as-prepared catalyst was characterized by FT-IR, SEM, EDX, TEM, ICP-MS, XPS, and XRD. The results showed that the Pd (0.2-0.6 nm) was successfully anchored on the magnetic silica material with boric acid group. The amount of Pd was 0.800 mmol g-1. This magnetic nanostructure (8-15 nm) is especially beneficial as a nanocatalyst because each nanoparticle can catalyze a reaction in a certain time without steric restriction, which could effectively improve the reaction efficiency. The current nanoparticles with the Pd catalyst could be used as a novel, green, and efficient heterogeneous catalyst for Suzuki reactions. This catalyst showed promising catalytic activity and excellent yields toward 14 kinds of Suzuki coupling reactions under mild reaction conditions, which was similar to homogeneous Pd and many reported heterogeneous Pd catalysts. In addition, the turnover number (TON) and turnover frequency (TOF) for the Suzuki reaction were high. TOF and TON were 9048 h-1 and 20 250 for the Suzuki reaction of bromobenzene and phenylboronic acid. Furthermore, the nanoparticles could be easily separated by a magnet, and could be used repeatedly seven times without any significant loss in activity.

[Determination of two alkaloids in Mongolian medicine Mauleri-Dabusi-4 soup by hollow fiber liquid phase micro-extraction coupled with ultra-high performance liquid chromatography].

In this study, a method combining hollow fiber liquid phase micro-extraction (HF-LPME) and ultra-high performance liquid chromatography (UPLC) was developed for the determination of two alkaloids (piperine and piperlonguminine) in Mongolian medicine Mauleri-Dabusi-4 Soup. The parameters affecting the micro-extraction efficiency were evaluated and optimized. The optimum conditions were as follows:polyvinylidence fluoride HF (54% pore size); 10 g/L NaCl; 30 µ L octanol as extraction solvent; 173 r/min stirring rate of extraction; and 128 min extraction time. The extracted drug was detected by UPLC. The calibration curves obtained good linear relationship in the concentration ranges of 100-8500 and 8.3-5000 µg/L for piperine and piperlonguminine, respectively. The enrichment factors of the method for piperine and piperlonguminine were achieved to be 59 and 65. The limits of detection were 2.2 µg/L for piperine and 2.5 µg/L for piperlonguminine. The method was successfully applied for the determination of alkaloids in Mongolian medicine Mauleri-Dabusi-4.

[Preparation of a hydrophilic-lipophilic composite solid phase extraction material and application in food safety inspection].

A copolymer of divinylbenzene and N-vinyl pyrrolidone (DVB-NVP) was synthesized for the purpose of solid phase extraction (SPE). Its performance as an SPE resin was evaluated using six model compounds having different polarities. Aqueous samples containing those compounds were applied to SPE cartridges containing the aforementioned copolymer as well as the classic C18 and Oasis HLB for comparison, and the SPE processed samples were analyzed by using high performance liquid chromatography (HPLC) for quantitation. Then, the copolymer DVB-NVP was sulfonated to modify the surface properties. The surface modified materials were used to analyse complex samples. The results showed that DVB-NVP had high recoveries for the six compounds ranging from 95.55% to 101.08% which were better than those of the C18 and were comparable to those of Oasis HLB. In applying to real samples, the recoveries for dimethyl phthalate, diethyl phthalate and dibutyl phthalate in liquor were 102.55%, 102.99% and 102.11%, with the RSDs of 2.11%, 1.69%, 0.79% respectively. Similarly, the recoveries for clonidine and cyproheptadine in pork were 89.23% and 91.42% with the RSDs of 8.21% and 8.86%, respectively.

[Application of solid phase extraction disk in the determination of acrylamide in tap water].

A simple and fast method of solid phase extraction (SPE) disk for the determination of trace acrylamide was developed. Using this new technique along with high performance liquid chromatography (HPLC) and ultraviolet spectroscopy (UV) detection, the feasibility of SPE disk method for rapid enrichment was demonstrated in the determination of trace acrylamide in 500 mL tap water. Active carbon was chosen as the adsorbent to be incorporated into the SPE disk as it gave the best adsorption efficiency. Experimental parameters including solvent, elution volume, elution rate, breakthrough volume were optimized to give the highest efficiency of extraction. Under proper chromatographic conditions, acrylamide was easily separated from other impurities. A linear relationship between peak area and mass concentration in the range 0.05-0.5 mg/L of acrylamide was established with a correlation coefficient of 0.998. The limit of detection was 20 ng/L. The recoveries for acrylamide with different concentrations and volumes ranged from 94.12% to 100.2%. The relative standard deviations (RSDs) were 2.09%-4.51% (n=3). The recovery for acrylamide spiked into a tap water sample was 79. 96%. The method is simple, fast, sensitive and suitable for the determination of acrylamide in tap water.

Preliminary studies of a novel multifunctional wide-bore electrophoresis system.

This paper presents the results obtained from a novel multifunctional analysis platform established on the basis of wide-bore electrophoresis (WBE) and CE. The WBE­CE system integrated various analytical steps including separation, transfer, reaction, detection, and storage into a single system. During the WBE­CE process, a distinct three-electrode format was adopted to continuously separate and transfer samples between WBE and CE without the interruption of switching on-and-off the power suppliers. This continuous mode of operation also helped to eliminate the need for exactly timing the transfer of specific samples zone from WBE to CE and avoided the danger of missing specific samples. Samples representing mixtures of acids, bases, or proteins were analyzed on this system for evaluating its feasibility and applicability. The results indicated that the resolution achieved on this WBE­CE system was better than either the WBE or the CE alone. Further, samples transferred out of the WBE system could participate in online reaction, such as enzymatic reaction in the CE. Alternatively, samples from the WBE system could be transferred out and stored offline in a vial for post-transfer reaction. The results demonstrated that this WBE­CE system has the potential to be a multifunctional platform for a range of applications.

Zone electrophoresis in an inner-cooling wide-bore electrophoresis system with UV detection.

A novel, high-performance wide-bore electrophoresis (WE) system with inner-cooling has been developed. By introducing the mode of a shell and tube heat exchanger into this system to remove Joule heat generated during electrophoresis, it is feasible to extend electrophoresis from the conventional capillary (i.d. <100 microm) to a wide-bore tube (i.d. >1000 microm). The wide tube allows the loading of over 1.0 microL of the sample with an LOD of 3.0 x 10(-4) mg/mL (signal-to-noise ratio, 3:1). Satisfactory separations of model compounds have been achieved on the WE system.