Monitoring and analytics of semivolatile organic compounds (SVOCs) in indoor air

This paper reviews literature information on the behaviour of semivolatile organic compounds (SVOCs) in the indoor environment, as well as the most likely emission sources. The consecutive stages of analytical procedures used for monitoring SVOCs in indoor environments are described. The most common approaches used for collecting samples from the gas and particulate phases are mentioned. The paper discusses and compares various types of sorbents and filters applied in dynamic, passive and denudational techniques, as well as the techniques used to liberate the SVOCs, including Soxhlet, sonication and microwave extraction. The main advantages and disadvantages of each technique are discussed, together with possible future trends. The approaches commonly used during the final determination step, such as gas chromatography and liquid chromatography, are presented together with their possible drawbacks, and ways of eliminating them are suggested. The review makes brief reference to the effects of human exposure to SVOCs in house dust and discusses the main aspects of the analytical procedures used to monitor the presence of SVOCs in this medium.     

Comparison of solid phase microextraction and hollow fiber liquid phase microextraction for the determination of pesticides in aqueous samples by gas chromatography triple quadrupole tandem mass spectrometry

This work compares two miniaturised sample preparation methods, solid phase microextraction (SPME) and hollow fiber liquid phase microextraction (HF-LPME), in combination with gas chromatography coupled to tandem mass spectrometry with a triple quadrupole analyzer for the determination of 77 pesticides in drinking water. In the case of SPME, extraction temperature and time were optimized by experimental design, although other parameters, as desorption time, pH, and ionic strength, were also evaluated. The extraction and desorption solvents [octanol/dihexyl ether (75:25, v/v) and cyclohexane, respectively], as well as the extraction and desorption time, ionic strength, and pH, were studied for the HF-LPME procedure. Under the optimal conditions, recoveries (70.2–113.5% for SPME and 70.0–119.5% for HF-LPME), intra-day precision (2.1–19.4% for SPME and 4.3–22.5% for HF-LPME), inter-day precision (5.2–21.5% for SPME and 8.4–27.3% for HF-LPME), and limits of detection, between 0.1 and 28.8 ng/L for SPME and 0.2 and 47.1 ng/L for HF-LPME and overall uncertainty (9.6–25.2% for SPME and 13.3–27.5% for HF-LPME) were established for both extraction procedures. Finally, the proposed methods were successfully applied to the analysis of 41 drinking water samples, and similar results were obtained with both extraction approaches.     

四氯合钯(II)喹诺酮配合物的合成及与DNA的作用和抗增殖活性

在酸性条件下, 分别合成了四氯合钯(II)离子与2种喹诺酮(诺氟沙星, NFLX＝C16H18N3O3F; 环丙沙星, CPLX＝C17H18N3O3F)离子形成的配合物(NFLXH)2[PdCl4]•2H2O (1)和(CPLXH)2[PdCl4]•2H2O (2). 用元素分析、IR、UV以及摩尔电导测定等方法对其进行了表征. 配合物1的晶体结构经X射线单晶衍射确定, 结构参数: 三斜晶系, P-1空间群, a＝0.84561(17) nm, b＝0.94191(19) nm, c＝1.2832(3) nm; α＝111.26(3)°, β＝97.23(3)°, g＝96.38(3)°, V＝0.9312(4) nm3, Z＝1, 最后吻合因子R＝0.040, wR＝0.088. 利用紫外光谱法、荧光光谱法对配合物与小牛胸腺DNA (ct-DNA)的作用进行了研究, 研究表明, 配合物对DNA的作用模式为插入作用, 与DNA的结合常数Kb分别为: Kb(1)＝2.06×104, Kb(2)＝2.43×104. 其后测试了配合物对体外肿瘤细胞的抗增殖活性. 经采用四甲基偶氮唑蓝分析法(MTT法)测试后发现配合物1和2对人肺腺癌A549细胞、人原髓细胞白血病HL-60细胞的增殖抑制作用显著强于相应的喹诺酮分子本身, 其中配合物2对人肺腺癌A549细胞增殖有明显的抑制作用, 抑制率可高达(95.4±3.7)%, 半数抑制浓度(IC50, 72 h)为(124.5±10.3) μmol•L－1.     

一种经MCM-41负载双齿膦钯(0)配合物催化的羰基化Suzuki偶联合成二芳酮的新途径

在催化量的MCM-41负载双齿膦钯(0)配合物存在下,芳基碘化物和芳基硼酸、一氧化碳在常压下能顺利进行羰基化Suzuki偶联反应,高产率地生成了各种二芳酮化合物。MCM-41负载双齿膦钯(0)配合物具有比PdCl2(PPh3)2 更高的活性和选择性,且可回收再用10次其活性基本不变,为各种功能化二芳酮的合成提供了方便实用的新途径。     

ELECTROCHEMICAL COPOLYMERIZATION OF DIBENZOFURAN AND 3-METHYLTHIOPHENE IN BORON TRIFLUORIDE DIETHYL ETHERATE

The copolymerization of dibenzofuran(DBF)and 3-methylthiophene(MET)was successfully achieved electrochemically by direct anodic oxidation of the monomer mixtures in boron trifluoride diethyl etherate.The effects of applied polymerization potential and the monomer concentration ratios on the copolymerization were investigated by linear sweep voltammetry and cyclic voltammetry(CV).The structure of copolymer films were investigated by UV-Vis,infrared spectroscopy,thermal analysis.As-formed novel copolymers ...     

Fe_3O_4 nano-whiskers by ultrasonic-aided reduction in concentrated NaOH solution

Fe 3 O 4 nano-whiskers were synthesized via ultrasonic-aided reduction of FeCl 2 ·4H 2 O with N 2 H 4 ·H 2 O in concentrated NaOH solution. Phase identification and morphology observation were conducted by X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM) and field emission scanning electron microscopy (FE-SEM). Face scanning energy dispersive spectrum (face scanning EDS) and two-dimensional fast Fourier transform (2DFFT) for element distribution were carried out for confirming compos...     

Novel bis-betaines and betaines within [1(4)]meta-heterophane frameworks

After prior selection of betaine building blocks for the construction of quadrupolar heterophane frameworks, a convergent "3+1" synthetic strategy is reported for the synthesis of the title macrocycles composed of heterocyclic betaine subunit(s). These typify the first example of simple cyclophanes constructed out of both highly pi-excessive and highly pi-deficient heteroaromatic moieties linked in a 1,3-alternating fashion. The chemical reactivity of the quadrupolar heterophanes 1a and 1c toward electrophiles under neutral conditions corroborated their bis-betaine structure. The structural features of the bis-betaines 1, betaines 2 x PF6 and 5 x X, and the corresponding dicationic [1(4)]heterophanes 3 x 2X and 4 x 2Cl were studied by 1H and 13C NMR spectroscopy and electrospray ionization mass spectrometry, and confirmed by single-crystal X-ray diffraction analysis of macrocycles 1a and 2a x PF6.     

Carbon composite electrodes: surface and electrochemical properties

Electrodes based on particulate carbon-epoxy or silicone composites have been formed and characterised using electrochemical methods, scanning electron microscopy and scanning electrochemical microscopy. These composites are rigid, exhibit high electrical conductivity and are stable in organic solvents for prolonged periods. The bulk resistance of the Araldite-M and Araldite-CW2215 based electrodes is low, 130+/-12 and 185+/-15 ohms, respectively. In contrast, the bulk resistance of the silicone based electrodes is 1480+/-112 ohms. The uncompensated resistance of electrochemical cells where the composites act as working electrodes is significantly larger than that expected on the basis of solution resistance alone, i.e., up to 7.5 kohms in the case of the silicone composites. These results are interpreted in terms of the presence of pores within the composite material. The response times of the composite electrodes to changes in the applied potential is between 3.1 and 7.2 ms which, although almost an order of magnitude longer than a comparable glassy carbon electrode, is sufficiently rapid to give useful voltammetric data for scan rates of several V s(-1). Close to ideal reversible cyclic voltammetry is observed for ferrocene under semi-infinite diffusion control for scan rates between 0.01 and 0.1 V s(-1) at the Araldite composites. In contrast, the large resistance associated with the silicone based materials causes quasi-reversible responses to be observed over this range of scan rate. Scan rate dependent cyclic voltammetry and time resolved chronoamperometry responses observed for ferrocene in solution are consistent with those expected for a random array of microelectrodes. Scanning electron microscopy and scanning electrochemical microscopy has been used to image the shape, size and electrochemical activity of the electroactive zones. In the case of Araldite-M, the quality of the electrode surface has been probed by comparing the rate of heterogeneous electron transfer at a composite microelectrode with that found for a carbon fibre electrode. The standard heterogeneous electron transfer rate constant, k degrees , is 6.0+/-0.1 x 10(-3) cm s(-1) for the composite compared to 1.5+/-0.1 x 10(-1) cm s(-1) for the carbon fibre electrode. While the smaller rate constant found for the composite suggests a less pristine surface, k degrees is sufficiently large to support reversible, electron transfer under typical electroanalytical conditions. These fundamental measurements will underpin the development of enzyme based biosensors for use in organic solvents.     

Asymmetric 1,3-dipolar cycloaddition of N-metalated azomethine ylides to methyl (S)-2-(p-tolylsulfinyl)acrylate. Synthesis of optically pure 2,4,5-trisubstituted 2,5-dihydro-1H-pyrroles

The first 1,3-dipolar reaction of azomethine ylides with optically pure vinyl sulfoxide are reported. The presence of the sulfinyl group increase the reactivity of the acrylate moiety as a dipolarophile, and the reactions evolve with complete regio- and endo-selectivities. Nevertheless, mixtures of the two diastereoisomers 4 and 5 (75-88% de) resulting from the anti dipole/s-cis dipolarophile and syn dipole/s-trans dipolarophile approaches, respectively, are obtained. The stereoselectivity can be controlled by using THF or MeCN as solvents or by changing the reaction temperature in MeCN. After separation of the cycloadducts, optically pure 2,5-dihydro-1H-pyrroles are easily obtained by pyrolytic desulfinylation.