Simultaneous determination of bisphenol A and alkylphenol in plant oil by gel permeation chromatography and isotopic dilution liquid chromatography-tandem mass spectrometry

A simple analytical method was developed for the simultaneous analysis of bisphenol A (BPA), nonylphenol (NP) and octylphenol (OP) in plant oil. The target compounds were extracted by cyclohexane/ethyl acetate (1:1), purified by gel permeation chromatography (GPC), and analyzed by liquid chromatography-electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) in the negative ion mode. An isolator column was attached in front of the injection valve of the LC to separate background contaminants. Recovery studies were performed at three fortification levels. Mean recoveries were from 92.9% to 119.0%, with an acceptable coefficient of variation (4.4-18.5%, n=6). The limits of quantification of the method were 2, 2 and 0.5 μg/kg for BPA, NP and OP, respectively. This method can be applied for screening and confirming target compounds in plant oil.     

Neutral and cationic chiral NCN pincer nickel(II) complexes with 1,3-bis(2'-imidazolinyl)benzenes: synthesis and characterization

Chiral 1,3-bis(2'-imidazolinyl)benzenes 1a-e easily undergo direct nickelation at the C2 position of the central benzene ring via the C-H bond activation in the reaction with anhydrous NiCl(2) giving neutral NCN pincer nickel(II) complexes 2a-e in 40-87% yields. Treatment of the nickel pincers 2a or 2c with AgBF(4) in CH(3)CN-CH(2)Cl(2) afforded the cationic nickel pincers 3a or 3c in good yields. All the complexes were characterized by elemental analysis, (1)H, (13)C NMR, and IR spectra. Molecular structures of the neutral complexes 2a, 2b and 2c as well as the cationic complex 3c have been determined by X-ray single-crystal diffraction. The cationic nickel pincers 3 are found to be effective catalysts for the Michael addition of ethyl 2-cyanopropionate to methyl vinyl ketone in the presence of i-Pr(2)NEt base with a catalyst loading of 5 mol% even at -78 °C, producing the adduct in >99% yield after 24 h albeit with no ee.     

系列双核Ln(III)配合物的晶体结构和磁性

合成了分子式为[Ln~2(phen)~2L],phen=C~1~2H~8N~2[ALn=Nd,L=(CH~3COO)~4(ONO~2)~2,BLn=Sm,L=(C~6H~5COO)~6,CLn=Eu,L=(C~6H~5COO)~6]3种同双核配合物。用X射线四圆衍射仪测定了3种化合物的结构。在化合物A分子中,2个Nd(III)原子由4个CH~3COO^-基团桥联,以phen和ONO~2^-为端基,构成了一个具有C~2对称性的双核分子。配合物B和C具有完全相同的结构,它们是以4个苯甲酸根为桥,2个phen和2个C~6H~5COO^-为端基的中心对称双核分子,其中6个苯甲酸根的成键状态可分为3种状况。在3种化合物中,每个Ln均为9配位,呈不规则多面体。Ln-Ln距离,A为0.397nm,B和C均为0.405nm。测定了各配合物的变温磁化率,通过对磁性质研究,发现化合物A在低温下具有反铁磁物质行为,并由理论拟合,求得了磁参数g,J值。     

Study on the anti‐sulfur‐poisoning characteristics of platinum–acetylide–phosphine complexes as catalysts for hydrosilylation reactions

A series of platinum–acetylide–phosphine complexes were synthesized and their anti‐sulfur‐poisoning characteristics investigated. In comparison with Speier's and Karstedt's catalysts, the platinum–acetylide–phosphine complexes exhibited both higher catalytic activity and selectivity for the β‐adduct for the hydrosilylation reactions under the same conditions. Furthermore, the complexes also exhibited a strong ability to resist to sulfur‐poisoning. This indicated that the alkyne ligands containing the silyl group had a strong impact on the hydrosilylation reaction. Copyright © 2014 John Wiley & Sons, Ltd.     

A core-shell magnetic mesoporous silica sorbent for organic targets with high extraction performance and anti-interference ability

C(18)-functionalized mesoporous silica shell was successfully fabricated on the surface of an Fe(3)O(4)/SiO(2) core to obtain an Fe(3)O(4)/SiO(2)/SiO(2)-C(18) magnetic microsphere. The microsphere exhibited high extraction efficiency to organic targets and strong anti-interference ability to natural organic matter. It could be easily isolated from water solution after extraction.     

Highly sensitive sensor for detection of NADH based on catalytic growth of Au nanoparticles on glassy carbon electrode

In this work, an electrochemical dihydronicotinamide adenine dinucleotide (NADH) sensor based on the catalytic growth of Au nanoparticles (Au NPs) on glassy carbon electrode was developed. Catalyzed by Au NPs immobilized on pretreated glassy carbon electrode, the reduction of AuCl₄ ^? in the presence of hydroquinone and cetyltrimethyl ammonium chloride led to the formation of enlarged Au NPs on the electrode surface. Spectrophotometry and high-resolution scanning electronic microscope (SEM) analysis of the sensor morphologies before and after biocatalytic reaction revealed a diameter growth of the nanoparticles. The catalytic growth of Au NPs on electrode surface remarkably facilitated the electron transfer and improved the performance of the sensor. Under optimal conditions, NADH could be detected in the range from 1.25?×?10^?6 to 3.08?×?10^?4 M, and the detection limit was 2.5?×?10^?7 M. The advantages of the proposed sensor, such as high precision and sensitivity, fast response, low cost, and good storage stability, made it suitable for on-line detection of NADH in complex biological systems and contaminant degradation processes.

Influence of ZrO2 on Carbon Monoxide Oxidation Over Pd/Al2O3

The influence of ZrO₂ on the properties of Al₂O₃ and performances of Pd/Al₂O₃ catalyst in CO oxidation have been investigated. TPD results show that the activity enhanced is due to the increase of the adsorptive capacity of CO and the activation of C=O bond after the introduction of ZrO₂.     

Simultaneous determination of carbohydrates and organic acids in beer and wine by ion chromatography

The simultaneous determination of mono-organic acids and carbohydrates by ion chromatography with both conductometric and pulsed amperometric detection is described. The carbohydrates, such as mannitol, arabinose, glucose, fructose, lactose, sucrose, raffinose, and maltose, as well as monoorganic acids including acetate, glycolate, formate, pyruvate, and fluoride are separated as anions by ion-exchange chromatography with 0.080 mol/L sodium hydroxide eluent at 1 mL/min within 12 min. Carbohydrates are determined by pulsed amperometric detection and mono-organic acids are determined by suppressed conductivity detection. The species in beverages are determined.