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91.
Air sampling of aromatic hydrocarbons in the presence of ozone by solid-phase microextraction 总被引:3,自引:0,他引:3
Effects of ozone on air sampling of standard gas mixtures of aromatic hydrocarbons were tested using solid-phase microextraction (SPME). Standard concentrations of ozone ranging from 10 ppb (v/v) to 6400 ppm (v/v) were generated using an in-house built ozone generator based on corona discharge. Effects of temperature, discharge voltage, and oxygen flow on the ozone generation were tested. The working dc voltage had the greatest effect on generated ozone concentration and was proportional to the ozone concentration. Generation temperature and oxygen flow rate were inversely proportional to ozone concentrations. Produced ozone was mixed with standard benzene, toluene, ethylbenzene, and xylenes (BTEX) gas at less than 100 ppb (v/v). Air samples were collected with poly(dimethylsiloxane) (PDMS) 100 microm SPME fibers and analyzed by gas chromatography (GC)-flame ionization detection (FID) and GC-MS. Significant reductions of BTEX concentrations were observed. In addition, some products of BTEX-ozone-oxygen reactions were identified. SPME worked well as a rapid sampler for BTEX and BTEX-ozone-oxygen reaction products. No significant deterioration of the PDMS coating and no significant reduction of absorption capacity were observed after repeated exposure to ozone. 相似文献
92.
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. 相似文献
93.
Jacek Lipok Tomasz Cierpicki Paweł Kafarski 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6-7):1657-1660
Alternaria sp. isolated from the surface of carrot ( Daucus carota ) seeds appeared to be able to degrade amino-(4-methoxyphenyl)-methanephosphonic acid using it as a sole source of carbon, nitrogen, and phosphorus for growth. 相似文献
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97.
Vladislav S. Olkhovsky Vittoria Petrillo Jacek Jakiel Wiesław Kantor 《Central European Journal of Physics》2008,6(1):122-127
The particle tunneling through a 3-D rectangular potential barrier has been studied. The simplest model for multiple internal
reflections has been assumed. The explicit expression for all the transmission and reflection probability amplitudes have
been derived, as well as the tunneling and reflection phase times.
相似文献
98.
Jacek Tabor 《Journal of Differential Equations》2002,180(1):171-197
99.
Jacek Cichon Andrzej Jasinski Anastasis Kamburelis Przemyslaw Szczepaniak 《Proceedings of the American Mathematical Society》2002,130(6):1833-1842
In this paper we discuss various questions connected with translations of subsets of the real line. Most of these questions originate from W. Sierpinski. We discuss the number of translations a single subset of the reals may have. Later we discuss almost invariant subsets of Abelian groups.
100.
Ciucanu I Kaykhaii M Montero L Pawliszyn J Szubra J 《Journal of chromatographic science》2002,40(6):350-354
A novel method for the continuous monitoring of thermooxidative degradation products of polystyrene by membrane extraction with sorbent interface (MESI) and gas chromatography (GC) is developed. The results are compared with solid-phase microextraction-GC, which can extract gases, vapors, and aerosols. The volatile and semivolatile degradation products are identified by mass spectrometry. The membrane used in the MESI-GC analysis shows a high permeation for volatile aromatic hydrocarbons; a low permeation for corresponding volatile aldehydes; and no permeation for less volatile alcohols, acids, and degradation products with a high molecular weight, thus reducing significantly the number of compounds detected from MESI-GC. Sensitivity of the method depends on the time of trapping, which is limited by the breakthrough of the trap. By heating the trap at fixed intervals of time, consecutive gas chromatograms are obtained. 相似文献