Poly(aryl ether ketone)s with (3‐methyl)phenyl and (3‐trifluoromethyl)phenyl side groups

New bisphenol monomers, (3‐methyl)phenylhydroquinone and (3‐trifluoromethyl)phenylhydroquinone, were prepared in a two‐step synthesis. A series of poly(aryl ether ketone)s were derived from these bisphenols via a nucleophilic aromatic substitution polycondensation with various bisfluoro compounds. The polycondensation proceeded quantitatively in tetramethylene sulfone in the presence of anhydrous potassium carbonate and afforded the polymers with inherent viscosities of 0.63–0.91 dL/g. The fluorinated polymers showed lower glass‐transition temperatures and higher thermal‐decomposition temperatures than the corresponding nonfluorinated polymers. The solubility of the polymers was improved by the introduction of bulky pendant groups. All the polymers formed transparent, strong, and flexible films, with tensile strengths of 86.4–102.0 MPa, Young's moduli of 2.28–3.03 GPa, and elongations at break of 14–42%. All the polymers had low dielectric constants of 2.70–2.83 at 1 MHz. Compared with the methylated polymers, the trifluoromethylated polymers exhibited lower water sorption, which was attributed to the stronger hydrophobicity of the fluorine‐containing groups. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3392–3398, 2002     

Biomonitoring: an appealing tool for assessment of metal pollution in the aquatic ecosystem

Wide occurrence of aquatic metal pollution has caused much attention. Biomonitoring offers an appealing tool for the assessment of metal pollution in aquatic ecosystem. The bioindicators including algae, macrophyte, zooplankton, insect, bivalve mollusks, gastropod, fish, amphibian and others are enumerated and compared for their advantages and disadvantages in practical biomonitoring of aquatic metal pollution. The common biomonitoring techniques classified as bioaccumulation, biochemical alterations, morphological and behavior observation, population- and community-level approaches and modeling are discussed. The potential applications of biomonitoring are proposed to mainly include evaluation of actual aquatic metal pollution, bioremediation, toxicology prediction and researches on toxicological mechanism. Further perspectives are made for the biomonitoring of metal pollution in aquatic ecosystem.     

离子型表面活性剂自组装体系在化学中的应用

本文介绍了离子型表面活性剂在氧化物表面自组装体系的原理及特点,离子型表面活性剂分子从溶液中自发地吸附到氧化物表面形成单分子胶束、双分子胶束和混合胶束,该体系对许多疏水性有机化合物以及经螯合有机基团的金属离子具有很强的吸附富集作用,本文根据不同自组装体系的结构分类详述了它们在分析化学和环境化学中应用研究,并且展望了该技术的应用前景。     

Cetyltrimethylammonium bromide-coated titanate nanotubes for solid-phase extraction of phthalate esters from natural waters prior to high-performance liquid chromatography analysis

As a novel nanomaterial, titanate nanotube has attracted considerable attention recently. However, most of the research work is focused on the preparation of this nanomaterial, and there is lack of information about its application in the fields of environmental monitoring and analytical chemistry. The purpose of our study is to investigate the feasibility of titanate nanotubes as an adsorbent for solid-phase extraction of several phthalate esters. The titanate nanotubes in this study were prepared by alkaline hydrothermal method. The cationic surfactant cetyltrimethylammonium bromide (CTAB)-titanate nanotube system was adopted based on hemimicelles/admicelles formed on the mineral oxide surface. It was shown in the batch experiment that the highest adsorption of phthalate esters onto the CTAB-titania and -titanate nanotube system occurred when the CTAB was varied from 100 to 200mgg(-1) titania or 80 to 300mgg(-1) titanate nanotube separately. According to the fluorescent spectra of a molecular probe, N-phenyl-1-naphthylamine, and the binding constant of solute in CTAB admicelles, the CTAB-titanate nanotube admicelles was more hydrophobic than CTAB-titania admicelles. Consequently, CTAB-titanate nanotube admicelles system was suitable for concentrating phthalates esters in water. An admicelle column was prepared with 100mg of titanate nanotubes by passing through 100mgg(-1) titanate nanotube of CTAB. And excellent collection yields were obtained for all the analytes when the sample volume was up to 1000mL. Under the optimal conditions, the detection limits found for di-n-propyl-phthalate, di-n-butyl-phthalate, di-cyclohexyl-phthalate, and di-n-octyl-phthalate were 39, 19, 35 and 20ngL(-1), respectively. The developed method was successfully applied to the analysis of several real water samples and satisfactory recoveries were achieved. All the results indicated the application potential of titanate nanotubes as solid-phase extraction adsorbents to pre-treat water samples.     

Evaluation of carbon nanotubes as a solid-phase extraction adsorbent for the extraction of cephalosporins antibiotics, sulfonamides and phenolic compounds from aqueous solution

The adsorptive potential of carbon nanotubes (single-walled carbon nanotubes and multi-walled carbon nanotubes) for solid-phase extraction of three groups of highly polar compounds (namely cephalosporins antibiotics, sulfonamides and phenolic compounds) was tested in this article. The analytes were strongly retained by the carbon nanotubes. And acceptable recoveries were obtained with the addition of ammonium acetate into eluents. The effects of solution pH on the recoveries of the antibiotics and phenolic compounds were examined. To check the retention abilities of three groups of compounds on carbon nanotubes, fixed amount of each analyte was added to different volumes (up to 500 mL) of aqueous solution, and then extracted by the sorbents. Comparative studies showed that the carbon nanotubes were much superior to C₁₈ for the extraction of the highly polar analytes. For the cephalosporins antibiotics and sulfonamides, the carbon nanotubes showed stronger retention capability than graphitized carbon blacks, but for some of the phenolic compounds graphitized carbon blacks seemed to be more suitable, indicating different retention mechanisms of these analytes. To further assess the enrichment ability of carbon nanotubes for highly polar compounds, the solid-phase extraction method of multi-walled carbon nanotubes packed cartridge was well developed, and the sulfonamides were used as model compounds. Under the optimal procedures, the detection limits of sulfonamides were in the range of 27-38 ng L⁻¹. The spiked recoveries from several real water samples obtained for sulfathiazole and sulfadiazine ranged from 55% to 79% and 72% to 92%, respectively, while the recoveries of sulfapyridine and sulfamethazine were in the range of 85-102%.     

高分辨气相色谱-高分辨质谱测定活性污泥中的多溴联苯醚

建立了利用高分辨气相色谱-高分辨质谱定量测定多溴联苯醚(PBDEs)的方法,参与了测定PBDEs的国际比对实验,实验结果表明该法是可行的。对不同地区（北京、山东临沂、上海）的3个污水处理厂的活性污泥进行了索氏提取、多层复合硅胶柱分离,然后用所建立的方法测定了19种多溴联苯醚单体的含量。结果表明,北京某污水处理厂的活性污泥中PBDEs的总量高于其他两者。     

用亲水性的C16硅胶反相色谱柱分离测定血清样品中的雌激素

将亲水性较强的C16硅胶反相色谱柱应用于血清样品中β-雌二醇、雌三醇、雌酮和17α-乙炔基雌二醇的分离。实验对分离条件进行了优化,得到的最佳色谱条件是：柱温40℃,流速1mL／min,以40％乙腈水溶液作等度洗脱。在此条件下．4种雌激素可在大约26min内实现基线分离,得到的4个色谱峰峰型对称。分离后的4种雌激素用紫外检测器在200nm处进行测定,方法对β-雌二醇、雌三醇、雌酮和17α-乙炔基雌二醇的检出限分别为0．024、0．015、0．012和0．016mg/L;校正曲线的线性范围为2-3个数量级,相关系数为0．998以上。方法应用于血清样品的测定,β-雌二醇、雌三醇、雌酮和17α-乙炔基雌二醇的标准加入回收率分别为96．3％、103．7％、100．1％和95．2％。     

卵黄蛋白原的分离测定及其在环境内分泌干扰物质筛选中的应用

环境内分泌干扰物的存在直接威胁野生动物的生存和人类的健康，对其作用机制及筛选方法的研究，已经成为环境科学研究的热点领域。近年来，卵黄蛋白原作为环境内分泌干扰物的“生物标志物”，得到了较深入的研究。本文讨论了卵黄蛋白原的分离测定方法及其在内分泌干扰物筛选中应用的最新进展，为建立更有效的卵黄蛋白分离测定方法及发展新的环境内分泌干扰物筛选技术提供参考。     

Actinide metals with multiple bonds to carbon: synthesis, characterization, and reactivity of U(IV) and Th(IV) bis(iminophosphorano)methandiide pincer carbene complexes

Treatment of ThCl(4)(DME)(2) or UCl(4) with 1 equiv of dilithiumbis(iminophosphorano) methandiide, [Li(2)C(Ph(2)P═NSiMe(3))(2)] (1), afforded the chloro actinide carbene complexes [Cl(2)M(C(Ph(2)P═NSiMe(3))(2))] (2 (M = Th) and 3 (M = U)) in situ. Stable PCP metal-carbene complexes [Cp(2)Th(C(Ph(2)P═NSiMe(3))(2))] (4), [Cp(2)U(C(Ph(2)P═NSiMe(3))(2))] (5), [TpTh(C(Ph(2)P═NSiMe(3))(2))Cl] (6), and [TpU(C(Ph(2)P═NSiMe(3))(2))Cl] (7) were generated from 2 or 3 by further reaction with 2 equiv of thallium(I) cyclopentadienide (CpTl) in THF to yield 4 or 5 or with 1 equiv of potassium hydrotris(pyrazol-1-yl) borate (TpK) also in THF to give 6 or 7, respectively. The derivative complexes were isolated, and their crystal structures were determined by X-ray diffraction. All of these U (or Th)-carbene complexes (4-7) possess a very short M (Th or U)═carbene bond with evidence for multiple bond character. Gaussian 03 DFT calculations indicate that the M═C double bond is constructed by interaction of the 5f and 6d orbitals of the actinide metal with carbene 2p orbitals of both π and σ character. Complex 3 reacted with acetonitrile or benzonitrile to cyclo-add C≡N to the U═carbon double bond, thereby forming a new C-C bond in a new chelated quadridentate ligand in the bridged dimetallic complexes (9 and 10). A single carbon-U bond is retained. The newly coordinated uranium complex dimerizes with one equivalent of unconverted 3 using two chlorides and the newly formed imine derived from the nitrile as three connecting bridges. In addition, a new crystal structure of [CpUCl(3)(THF)(2)] (8) was determined by X-ray diffraction.     

Determination of methyltin compounds in urine of occupationally exposed and general population by in situ ethylation and headspace SPME coupled with GC-FPD

A method for the determination of methyltin compounds in human urine samples was developed using headspace solid-phase microextration (HS-SPME) coupled with gas chromatographic separation and flame photometric detection. Three methyltin compounds, monomethyltin (MMT), dimethyltin (DMT), and trimethyltin (TMT) were in situ ethylated by sodium tetraethylborate (NaBEt₄) for SPME and GC-FPD analysis. Under the optimized condition, the detection limits of MMT, DMT, and TMT were 8.1, 2.5 and 5.6 ng Sn L⁻¹, and the relative standard deviations were 11.0%, 7.3% and 4.0%, respectively. Methyltin compounds in thirteen urine samples from occupationally exposed population and two from general population were analyzed by the proposed method. The concentrations of total methyltin in the tested urine samples of occupationally exposed population ranged from 26.0 to 7892 ng Sn L⁻¹, and the average level is higher than those of the two non-occupationally exposed individuals. The methyltins in urine were adjusted by osmolality in order to enhance the comparability of different urine samples and the feasibility of this correction method was validated.