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Di-region theory, the theory for the mechanism of carcinogenesis, has been extendedsuccessfully on the quantitative Structure-carcinogenic activity relationship (QSCAR) of 63aromatic amines. A quantitative equation for the QSCAR of aromatic amines has been estab-lished by the mechanism conception of the specialized di- functional alkylation between thenitrenium ion of the amino group and the epoxide of the aromatic ring. The agreementbetween calculation and experiment comes up to 98%. Thus, it can now express the puzzlingvariation of the carcinogenicity of aromatic amines, as a comprehensible structure-chemicalreactivity relationship. 相似文献
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伊敏煤田伍牧场矿区煤中多环芳烃分布特征 总被引:6,自引:2,他引:6
伊敏煤田伍牧场矿区储藏着丰富的煤层,有从褐煤至瘦煤连续变化的系列煤样。对该煤系样品索氏抽提物中芳烃馏分进行GC/MS分析,取得从萘系至m/e496分子量的一个系列的芳烃分布数据。煤中多环芳 鉴定是通过气相色谱的保留指数,质量色变和质谱多个方面考证而定出本系列样品中57个化合物的同系物。 相似文献
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本文研究云南宝秀盆地一个钻孔不同深度的泥炭和褐煤抽出物芳烃馏分中多环芳烃的组成。用GC和GC/MS鉴别了它们的组份,结果表明,从双环和三环单芳构化、双芳构化、三芳构化到四环双芳构化、三芳构化及四芳构化和五环单、双芳构化、三芳构化、四芳构化以及C环开裂的萜类化合物均有不同含量的存在,这说明在煤化过程早期芳构化就进行到相当的深度,也说明云南陆源高等植物,尤其是喜温树类的造煤物种为宝秀盆地提供了特殊的芳构化有机组成系列。 相似文献
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A new sampling method of ambient air analysis using carbonized fibrous resin as a sorbent for polycyclic aromatic hydrocarbons(PAHs) was reported.The physical and chemical properties of the carbonized fibrous resins were measured.The sample pretreatment with ultrasonic extraction and subsequent clean-up elution through a silica gel column was optimized.The suitable ultrasonic extraction conditions were selected as follows:resin weight was 1.5g,ultrasonic extraction time 20min,volume of extraction solvent 100 ml and extraction operation times 2-3.The concentrated extractable organic matter was submitted to next step of clean-up procedure of adsorption chromatography on silica gel column/n-hexane and a mixture of dichloromethene:n-hexane solution 2:3(v/v).The PAHs fractions in the real samples from Changzhou,China were particularly analyzed using GC-MS data system and the data of mass spectra,retention times and scan numbers of the real samples were compared with that of the standards of 16 PAHs listed by the US EPA as “priority pollutants” of the environment. The pretreatment of samples of ambient air with carbonized fibrous resin as a sorbent for PAHs is proved to be reliable and might be used for the procedure of the determination of PAHs in atmospheric environment. 相似文献
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LING Daren LIU Bing WU Guoqi Department of Applied Chemistry Jiangsu Institute of Petrochemical Technology Changzhou China 《Chinese Journal of Reactive Polymers》2002,(1)
1. INTRODUCTION When investigating contaminated sites it is often essential to determine specific pollutants in a large number of ambient air samples. Amongst these sites, polycylic aromatic hydrocarbons (PAHs) are a major class of compounds that hav… 相似文献
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GC-MS法测定焦化厂气溶胶中多环芳烃 总被引:2,自引:0,他引:2
利用气相色谱-质谱(GC-MS),电子轰击离子化(EI)法测定焦化厂气溶胶中多环芳烃的含量。超声波抽提气溶胶样品,用GC-MS的选择离子监测(SIM)方式测定EPA提出的优先监测的16种多环芳烃的含量。该法的检出限为0.167pg·m~(-3),PAHs的回收率为85.1%~110.5%,相对标准偏差为4.62%~19.4%。应用该法测定气溶胶中PAHs获得满意的结果。 相似文献
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Abstract— –Triplet states of several large polycyclic aromatic hydrocarbons together with their lifetimes have been determined both in fluid solution and in the solid state using a spectrophoto-metric technique.
Excited states and lifetimes of some solid charge transfer complexes between the hydrocarbons and chloranil have been examined.
The assignment of the1 B b states of some of the hydrocarbons have been made from the energies of the triplet states. 相似文献
Excited states and lifetimes of some solid charge transfer complexes between the hydrocarbons and chloranil have been examined.
The assignment of the
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—Aromatic hydrocarbons incorporated into cetyltrimethylammonium chloride (CTACl) or sodium dodecylsulphate (SDS) micelles are efficiently quenched and photobleached by carbon tetrachloride. Similar results were obtained employing chloroform, but the efficiency of this compound as a quencher is nearly 103 times smaller than that of carbon tetrachloride.
Bimolecular quenching constants, with the quencher concentration given in moles per liter of micellar pseudophase, have been evaluated and compared with those obtained in homogeneous solutions. For slow processes, the values obtained would indicate that the polarity sensed by the probe depends both upon the probe and the surfactant. For diffusionally controlled processes (i.e. quenching of biphenyl), bimolecular quenching constants are considerably smaller in the micellar pseudophase. For these processes the pseudo-first-order quenching rate constants are larger in SDS than in CTACl micelles. This effect is partly due to the smaller size of the SDS micelle but also is a consequence of a lower "microviscosity" of these micelles. 相似文献
Bimolecular quenching constants, with the quencher concentration given in moles per liter of micellar pseudophase, have been evaluated and compared with those obtained in homogeneous solutions. For slow processes, the values obtained would indicate that the polarity sensed by the probe depends both upon the probe and the surfactant. For diffusionally controlled processes (i.e. quenching of biphenyl), bimolecular quenching constants are considerably smaller in the micellar pseudophase. For these processes the pseudo-first-order quenching rate constants are larger in SDS than in CTACl micelles. This effect is partly due to the smaller size of the SDS micelle but also is a consequence of a lower "microviscosity" of these micelles. 相似文献
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2-戊酮、芳香醛与芳香胺的Mannich反应邹君华,易林(西南师范大学化学系,重庆630715)关键词Mannich反应,芳香醛,芳香胺,2-戊酮80年代以前,一般认为芳香胺与甲醛及含有α-氢的酮不能发生Mannich反应 ̄[1,2,3],相应的Ma... 相似文献
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Abstract— The rates of the photosensitized immobilization of the nauplii of the crustacean Artemia salina were measured as a function of irradiation time and the amount of light absorbed by the sensitizers. The nauplii were incubated in the dark in dilute solutions of the sensitizers for periods of 2 and 22 h prior to irradiation. Nineteen carcinogenic and 22 noncarcinogenic polycyclic aromatic hydrocarbons were used as sensitizers. Relative photodynamic activities (RPA) were determined from the rates of immobilization using benz[ c ]acridine as a standard (RPA = 1). High RPA was restricted to carcinogenic compounds with 4 and 5 fused rings, compounds with 6 or more fused rings had low RPA regardless of their carcinogenic activities. The correlation of RPA with carcinogenic activity was excellent ( P = 0.006 and 0.009 for the 2 and 22 h dark incubations, respectively). It is suggested that carcinogenesis by polycyclic aromatics may result from sublethal photodynamic effects. 相似文献
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Abstract— The energies of the lowest excited singlet, Es, and triplet, Et, states, and singlet-triplet splitting energies, ΔEs,t, were determined on 18 carcinogenic and 31 noncarcinogenic polycyclic aromatics. A highly significant correlation was found between carcinogenic activity and the energy of the excited singlet state. Compounds with an Es < 312 kJ/mol were 4.8 times more likely to be carcinogens than those compounds with Es 312 kJ/mol (P= 0.015). Compounds whose singlet energies fell within the narrow range of 297 ≤Es≤ 310 kJ/mol were 22.8 times more likely to be carcinogens than those compounds which fell outside this range (P= 0.00006). A significant correlation between carcinogenic activity and Et energies was not found, while the correlation involving ΔEs,t energies was intermediate between the Es and Et correlations. The phosphorescence lifetimes, τp, of the 18 carcinogenic aromatics and 27 of the noncarcinogenic aromatip were determined, and were shown not to be correlated with carcinogenic activity. When either the Et or ΔEs,t energies were plotted as a function of Es it was found that the carcinogens tended to form in an elliptical cluster. Compounds whose Es and Et energies placed them within the ellipse were 9.7 times more likely to be carcinogens than those compounds which fell outside the ellipse (P= 0.002), while with the Es, ΔEs,t ellipse, compounds which fell inside were 20.6 times more likely to be carcinogens than those which fell outside (P= 0.0004). Es, Et, ΔEs,t and τp values were also determined on 12 carcinogenic and 4 noncarcinogenic alkyl substituted benz[a]anthracenes. There was no significant difference between the carcinogens and noncarcinogens and the “elliptical” correlation predicted both the carcinogens and noncarcinogens to be carcinogenic. The results suggest that either some property(ies) of the lowest excited singlet state, but not its energy, or some molecular property(ies) which runs parallel to singlet state energies may be important in determining carcinogenic activity in polycyclic aromatics. 相似文献
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利用一步紫外激光脱附和电离的飞行时间质谱法,测定了几种芳香烃分子:苯并[e]芘、荧蒽、肉桂酸和2,5-二羟基苯甲酸的质谱。实验结果发现,苯并[e]芘发生有效的“软”电离,属于双光子电离过程。而荧蒽需吸收三个光子才能电离。对2,5-二羟基苯甲酸和肉桂酸,在紫外脉冲激发作用下除了自身电离外,还发生了分子离子反应。 相似文献
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The Meso-region theory of polycyclic aromatic hydrocarbon (PAH) carcinogenesis predicts that the development of pronounced carcinogenicity depends on the introduction of a good leaving group on alkyl side-chains attached to the exceptionally reactive meso-anthracenic or L-region positions of PAHs. Thus, the first step in carcinogenesis by methylated PAHs such as 7,12-dimethylbenz[a]anthracene (DMBA) would be the hydroxylation of the L-region methyl groups, particularly the 7-methyl group. The second would be the formation of a metabolite, e.g. a sulfate ester, which is expected to be a good leaving group capable of generating a highly reactive benzylic carbocation. 7-Hydroxymethyl-12-methylbenz[a]anthracene (7-HMBA) is a metabolite of DMBA, and sulfation of 7-HMBA to a 7-sulfoxymethyl metabolite (7-SMBA) is a known Phase II metabolic process designed to facilitate excretion, but actually enabling more destructive side-reactions. These side-reactions occur with generation of an electrophilic 7-methylene carbonium ion, and/or by in vivo halide exchange to provide neutral side-products more capable of entering cells, especially those of DMBA target tissues. Electrospray ionization mass spectrometry (MS) enabled us to visualize 7-SMBA as an intact m/z 351 conjugate anion by negative mode, and as a released m/z 255 carbonium ion by positive mode. Upon prolonged refrigeration, 7-SMBA accumulated an m/z 383 photooxide, which appeared capable of re-evolving the starting material as visualized by tandem quadrupole MS, or MS/MS. The 7-SMBA carbonium ion provided interpretable fragments when studied by fragment ion MS/MS, including those representing the loss of up to several protons. Subtle differences in this property were encountered upon perturbing 7-SMBA, either by warming it at 37 degrees C for 2 h or by substituting the initial sulfoxy group with an iodo group. Side-reactions accounting for such proton losses are proposed, and are of interest whether they occur in the mass spectrometer, in solution or both; these proposals include acidity at the 12-methyl position and cyclization between the 12-methyl group and the adjacent C-1 position. It is also suggested that such side-reactions may comprise one route to relieving steric strain arising between the 12-methyl group and the angular benzo ring of 7-SMBA. 相似文献
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In this research,static adsorption of three polycyclic aromatic hydrocarbons(PAHs),naphthalene,acenaphthene,and fluorene,from aqueous solutions onto hypercrosslinked polymeric adsorbent within the temperature range of 288-308 K is investigated.Several isotherm equations are correlated with the equilibrium data,and the experimental data is found to fit the Polanyi-Dubinin-Manes model best within the entire range of concentrations,providing evidence that pore-filling is the dominating sorption mechanism for PAHs.The study shows that the molecular size of adsorbates has distinct in-fluence on adsorption capacity of hypercrosslinked polymeric adsorbent for the PAHs;the larger the adsorbate molecular size,the lower the adsorption equilibrium capacity.Based on the Polanyi-Dubinin-Manes model,the molecular size of adsorbates was introduced to adjust the adsorbate molar volume.Plots of qv vs.(σε /Vs) are collapsed to a single correlation curve for different adsorbates on hypercrosslinked polymeric resin. 相似文献