Influence of the bisphenol structure on the direct synthesis of sulfonated poly(arylene ether) copolymers. I

New sulfonated poly(arylene ether sulfone) copolymers with high molecular weights were successfully synthesized with controlled degrees of disulfonation of up to 70 mol % via the direct copolymerization of sulfonated aromatic dihalides, aromatic dihalides, and one of four structurally distinct bisphenols. The disodium salts of the 3,3′‐disulfonated‐4,4′‐dichlorodiphenyl sulfone and 3,3′‐disulfonated‐4,4′‐difluorodiphenyl sulfone comonomers were synthesized via the sulfonation of 4,4′‐dichlorodiphenyl sulfone or 4,4′‐difluorodiphenyl sulfone with 30% fuming sulfuric acid at 110 °C. Four bisphenols (4,4′‐bisphenol A, 4,4′‐bisphenol AF, 4,4′‐biphenol, and hydroquinone) were investigated for the syntheses of novel copolymers with controlled degrees of sulfonation. The composition and incorporation of the sulfonated repeat unit into the copolymers were confirmed by ¹H NMR and Fourier transform infrared spectroscopy. Solubility tests on the sulfonated copolymers confirmed that no crosslinking and probably no branching occurred during the copolymerizations. Tough, ductile films were solvent‐cast that exhibited increased water absorption with increasing degrees of sulfonation. These copolymers are promising candidates for high temperature proton‐exchange membranes in fuel cells, which will be reported separately in part II of this series. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2264–2276, 2003     

Photo-oxidative degradation of bisphenol A polycarbonate and its possible initiation processes

During UV degradation of bisphenol A polycarbonate (BPA-PC), photo-Fries rearrangements and photo-oxidation reactions take place, however, in outdoor exposure conditions the photo-oxidation reaction is the most dominant one. To initiate this autocatalytic oxidation process, an initiating radical is required. In this research two possible sources for photo-initiation are explored, viz. hydroperoxides and peroxides formed by thermo-oxidation and charge transfer complexes between the polymer and oxygen. A comparison of the photodegradation rate of thermo-oxidized and undegraded polycarbonate samples was made. It was shown that the formed thermo-oxidation products in BPA-PC did not affect the photo-oxidation rate. Charge transfer complexes (CTCs) between oxygen and polycarbonate were studied by UV absorption spectroscopy at different air pressures. The concentration of CTCs increased with oxygen pressures. These CTCs absorb wavelengths in the region of terrestrial sunlight and could cause the initiation of the photo-oxidation. The influence of oxygen pressure on the photodegradation of BPA-PC was studied by irradiating the samples with a by the polymer absorbing wavelength, viz. 250 nm. The absorption of this wavelength leads to photo-Fries products. It was shown that at higher oxygen pressures the rate of the photo-Fries reaction is reduced, which was explained by quenching of the photo-Fries reaction by oxygen.     

Simultaneous determination of bisphenol A, triclosan, and tetrabromobisphenol A in human serum using solid-phase extraction and gas chromatography-electron capture negative-ionization mass spectrometry

This study aimed at optimizing and validating a sensitive method for simultaneous determination of bisphenol A (BPA), triclosan (TCS), and tetrabromobisphenol A (TBBPA) in human serum using solid-phase extraction (SPE) and gas chromatography coupled to electron-capture negative-ionization mass spectrometry (GC-ECNI/MS). Sample preparation involved denaturation of serum proteins with formic acid followed by SPE on an Oasis HLB cartridge. Fractionation was performed on Florisil from which the phenolic compounds were eluted with methanol-dichloromethane (DCM) (5:1, v/v). The phenolic fraction was further derivatized with pentafluoropropionic acid anhydride (30 min at 70 degrees C). Further liquid-liquid partitioning using hexane-DCM (4:1, v/v) and K(2)CO(3) 3% aqueous solution was used to eliminate excess reagent and acidic by-products formed during derivatization. The cleaned extract was injected into a GC-ECNI/MS system operated in selected ion monitoring mode. For thorough method validation, each step of the procedure was rigorously optimized. The method limits of quantitation for BPA, TCS, and TBBPA were 0.28 ng mL(-1), 0.09 ng mL(-1) and 0.05 ng mL(-1), respectively. Furthermore, the method was applied to 21 Belgian human serum samples. The median concentrations obtained for BPA (0.71 ng mL(-1)) and TCS (0.52 ng mL(-1)) in Belgian human serum samples were similar to previously reported data for human fluids. Slightly higher levels of TBBPA (0.08 ng mL(-1)) were found in Belgium samples compared to Norwegian serum.     

Sequential ene, Diels-Alder reactions of AF4-yne with 1,3,5-cycloheptatriene

(4,5-Dehydro)-1,1,2,2,9,9,10,10-octafluoro [2.2]paracyclophane (AF4-yne) undergoes an ene reaction with 1,3,5-cycloheptatriene, the adduct of which subsequently undergoes a further Diels-Alder reaction with a second equivalent of AF4-yne to give two stereoisomeric 2:1 adducts. A very small amount of the classic 1:1 Diels-Alder adduct also can be isolated from the reaction. Structure assignments of all products were determined by NMR through a series of H1-H1, H1-C13 one bond, and H1-C13 two and three bond correlation experiments as well as H1-H1 NOE experiments.     

基于金-银纳米异质二聚体的双酚A的表面增强拉曼光谱检测方法

构建了一种基于金-银纳米异质二聚体的表面增强拉曼光谱(SERS)检测新方法,实现对双酚A(BPA)的快速、高灵敏传感检测。以DNA分子为模板定向制备高产率的、内嵌有BPA核酸适配体序列的金-银纳米异质二聚体,利用二聚体对其表面拉曼活性分子的增强作用,从而获得强烈的SERS信号。当体系中存在BPA时,会与金纳米颗粒表面修饰的核酸适配体特异性识别,使得金-银异质二聚体解离,体系的SERS信号减弱。利用BPA的浓度与SERS信号强度的变化关系建立标准曲线,达到快速定量检测的目的。结果表明:构建的SERS方法可在30min内实现BPA的高灵敏、高特异性检测。在优化条件下,方法线性范围为0.05~10μg/L,检测限为0.038μg/L。通过实际样品的加入回收实验,证明该方法具有很好的实际应用价值。     

高效液相色谱-串联质谱法测定儿童和成人尿液中双酚A、四溴双酚A和辛基酚

采用高效液相色谱-串联质谱法定量检测人体尿液中痕量双酚A、四溴双酚A和辛基酚.将解冻后的尿样酶解,经液液萃取、旋蒸至干,甲醇定容后分析.3种目标物质在0.2～50 μg/L质量浓度范围内线性关系良好,相关系数均大于0.99,定量限(LOQ)在0.05 ～ 0.27 μg/L之间.在5,10和50 μg/L加标水平下,平均回收率为85.7％～118.6％,相对标准偏差RSD(n=3)为4.1％ ～10.5％.20组儿童与成人的尿样结果表明,尿样中均检出3种目标物,其中,四溴双酚A和辛基酚在儿童及成人尿样中的暴露浓度基本相同,但是双酚A的暴露水平具有显著性差异(儿童＞成人).     

Isotope dilution gas chromatography with mass spectrometry for the analysis of 4‐octyl phenol, 4‐nonylphenol,and bisphenol A in vegetable oils

By the combination of solid‐phase extraction as well as isotope dilution gas chromatography with mass spectrometry, a sensitive and reliable method for the determination of endocrine‐disrupting chemicals including bisphenol A, 4‐octylphenol, and 4‐nonylphenol in vegetable oils was established. The application of a silica/N‐(n‐propyl)ethylenediamine mixed solid‐phase extraction cartridge achieved relatively low matrix effects for bisphenol A, 4‐octylphenol, and 4‐nonylphenol in vegetable oils. Experiments were designed to evaluate the effects of derivatization, and the extraction parameters were optimized. The estimated limits of detection and quantification for bisphenol A, 4‐octylphenol, and 4‐nonylphenol were 0.83 and 2.5 μg/kg, respectively. In a spiked experiment in vegetable oils, the recovery of the added bisphenol A was 97.5–110.3%, recovery of the added 4‐octylphenol was 64.4–87.4%, and that of 4‐nonylphenol was 68.2–89.3%. This sensitive method was then applied to real vegetable oil samples from Zhejiang Province of China, and none of the target compounds were detected.     

Degradation of bisphenol A by <Emphasis Type="Italic">Bacillus pumilus</Emphasis> isolated from kimchi,a traditionally fermented food

Novel bisphenol A (BPA)-degrading bacterial strains, designated as BP-2CK, BP-21DK, and BP-22DK, were isolated from kimchi, a traditionally fermented food. These isolates were identified as Bacillus pumilus and efficiently degraded BPA in a medium supplemented with nutrients such as peptone, beef extract, and yeast extract. Strains BP-2CK, BP-21DK, and BP-22DK successfully degraded 25, 25, and 50 ppm of BPA, respectively, and all strains exhibited BPA-degrading activity in the presence of 10% NaCl. Accumulation of the metabolites including 4-hydroxyacetophenone, one of the intermediates produced by the other BPA-degrading bacteria, was not observed in BPA degradation by the isolated strains. These results indicate that the isolated food-derived bacteria are applicable for the construction of efficient and safer systems for the removal of BPA.     

An Electrochemical Aptamer Biosensor for Bisphenol A on a Carbon Nanofibre-silver Nanoparticle Immobilisation Platform

A nanocomposite platform of silver nanoparticles and carbon nanofibres (AgCNFs) was used to immobilise a bisphenol A specific 63-mer ssDNA aptamer to form a biosensor. The fabrication process of the biosensor was studied with electrochemical impedance spectroscopy and cyclic voltammetry in the presence of [Fe(CN)₆]^3−/4− as redox probe. The biosensor detected bisphenol A in a linear range of 0.1–10 nM, with a limit of detection of 0.39 nM using square wave voltammetry (SWV). The biosensor exhibited good selectivity in the presence of interfering species at 100-fold concentrations and was used to detect BPA in real water sample.     

A Simple and Highly Stable Porous Gold‐based Electrochemical Sensor for Bisphenol A Detection

A porous gold electrode with a uniform pore size was prepared by a simple single potential step method. It provided around 19 times more surface area than a bare gold electrode. The porous gold electrode, without any modification, exhibited good electrocatalytic activity towards the oxidation of bisphenol A (BPA). The effect of the pH and scan rate, on the porous gold electrode was studied and discussed. Under optimum conditions of the flow system, the calibration plot of BPA was linear over a wide range of concentration, from 2.0 nM to 800 nM (R²=0.999), and the detection limit was 2.0 nM (s/n=3). It was of interest that, the porous gold electrode showed an exceptional result in minimizing the fouling from the oxidation product of BPA and led to a very high operational stability of the electrode for the detection of BPA (560 consecutive times). The porous gold electrode showed good fabrication reproducibility and can be used to detect bisphenol A that leached from baby bottles and drinking water bottles. The obtained results were in good agreement with the GC‐MS method (P >0.05).