氯化铜催化二噁英生成实验及指纹特性分析

氯化铜被认为是对二■英(PCDD/F)生成促进作用最强的金属催化剂,温度和氧气含量是影响其催化二■英生成的关键因素.本文选取250～550℃间8个不同温度点及0～20%间4种不同氧气含量,系统性地研究了温度和氧气含量对含氯化铜模拟飞灰(MFA)生成二■英的影响,并通过分析指纹特性探讨二■英的生成路径和机理.结果发现,290～350℃之间二■英生成量较高,且在290℃时二■英总量达到最大值;氧气含量为10%时二■英生成量达到最高.研究二■英同分异构体分布可从分子层面为研究其生成路径和机理提供重要信息,因此,本文分析了四至八氯代PCDD/F的全部异构体的分布.结果表明,在本文所选取的温度和氧含量范围内,温度对二■英生成路径的影响高于氧气含量.最后,重点讨论了2,3,7,8位氯取代的17种有毒异构体的分布随温度和氧气的变化情况及生成路径.利用主成分分析法(PCA)证实了氯化铜催化二■英从头合成过程中存在经由氯酚路径生成的异构体,并讨论了不同工况下氯酚路径对二■英生成的影响.     

Polychlorinated dibenzo‐p‐dioxins and dibenzofurans (PCDD/Fs) in dated environmental samples,and their connection to known sources

This article investigates available environmental data from measurements of the everywhere present contaminants polychlorinated dibenzo‐p‐dioxins and dibenzofurans (PCDD/F) in dated trends in sediment, soil and herbage from locales in Europe and North America. The PCDD/F data are examined in relation to potential major PCDD/F sources based on volume: wood and coal, example of natural combustion; pentachlorophenol (PnCP), example of chlorinated aro‐matics; and polyvinyl chloride (PVC) pyrolysis, example of chlorinated aliphatic. Collected PCDD/F data of congener sums and 2, 3, 7, 8‐substituted congener (PCDD/F profiles) have been investigated with multivariate methods: principal component analysis (PCA) and partial least squares projection to latent structures model (PLS). The results show that PCDD/F data from 12 locales can be separated in one to three independent profiles. Normally one profile is related to the PCDD/F found in PnCP and another to combustion. A subtype of the ‘PnCP’ and ‘combustion’ profiles indicates PCDD/F contributions from PVC‐related combustions. The environmental profiles exhibit some differences from the suggested sources. The relatively unprotected PCDD/F related to PnCP is suggested to have passed photolytic and/or thermal dechlorinations. Lower‐chlorinated congeners in environmental profiles related to combustion appear to have been influenced by environmental distribution processes. PCDD/F data before industrial production of chlorinated organics have only limited similarity to PCDD/F in technical PnCP profiles; an average 4.6% of the PCDD/F is related to PnCP. This suggests that PnCP similarity in recent deposition profiles cannot be a result of environmental transformation. The average proportion of PnCP‐related PCDD/F profile in recent depositions is 35% with North America high (average 57%) and Europe low (average 24%).     

Temporal limitations in the use of potassium dichromate as a blood preservative for the analysis of organohalogenated contaminants including polybrominated diphenyl ethers,dioxins and PCBs

Previous studies described the use of potassium dichromate (K₂Cr₂O₇) to successfully preserve whole blood for up to 34 days at room temperature (20–22°C) for analysis of chlorinated dioxins, dibenzofurans and PCBs. Potassium dichromate has been successfully employed as a preservative for cows’ milk and in a World Health Organization study of human milk. The use of two 100?mg tablets in 40 to 100?mL of whole blood in anticoagulant was found to provide almost identical levels of dioxins, dibenzofurans, PCBs and lipids as found in frozen comparison blood at??70°C which is generally regarded as the gold standard for blood preservation. Potassium dichromate was found to be preferable to 20 and 40% ethyl alcohol for this preservation. This finding opens opportunities for preservation under field conditions in developing countries where neither electricity nor dry ice is available. Not having to use dry ice for shipping also allows more flexibility in the choice of commercial carriers for transporting blood to an analytical laboratory. It is recommended considering a number of compounds in addition to those studied in our first report and extending the time beyond 34 days in order to determine if longer storage might also be feasible. Data on polybrominated diphenyl ethers (PBDEs), as well as polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and selected polychlorinated biphenyls (PCBs) are reported. For the present study 3 and 6 months were chosen in potassium dichromate at room temperature compared to freezing at ?70°C. Data indicate that these times exceed the limits of efficacy of potassium dichromate for whole blood preservation. This was attributed to degradation of the lipid component of the blood. Since dioxins and closely related structural analogues are traditionally reported as lipid normalized blood levels, this degradation of lipids provides erroneous results. Therefore, potassium dichromate is not recommended for long-term storage beyond 34 days at room temperature. It is planned to study the time period between one and three months and higher temperature preservation for shorter time periods, simulating conditions in tropical countries, to attempt to extend further the ease and convenience of chemical preservation of blood.     

二噁英/呋喃类的PGC柱-高效液相色谱精制法

针对现行二英物质的三氧化二铝柱分离净化技术的缺陷,介绍了目前最新的二英类物质间的单离纯化技术———高效PGC(PorousGraphiticCarbon)柱-液相色谱分离方法的实际应用。通过13C-二英类物质的实际分离条件以及分析流程的研究,二英类的最终纯化技术达到自动化。对实际土壤中二英类物质的分析结果表明:单分离二英类物质组分效果良好,回收率稳定达到99%以上,自动化程度高;溶剂用量少,安全性好;排除了人为干扰,减少了操作过程的失败。      

Determination of PCBs, PCDDs and PCDFs in insulating oil samples from stored Chinese electrical capacitors by HRGC/HRMS

Homologue and congener profiles of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in commercial PCBs formulations are key information for the source identification of PCBs contamination as well as for the risk assessment caused by potential exposure. The isotope dilution technology in combination with high resolution gas chromatography-high resolution mass spectrometry (HRGC/HRMS) has made the accurate determination of such profiles possible. So far, various commercial PCB formulations except Chinese products have been successfully determined. Two PCBs containing insulating oil samples from stored Chinese electrical capacitors have been determined with the same methodology for comparability. The total concentration PCBs in two oil samples were 790 000 μg g⁻¹ and 720 000 μg g⁻¹, respectively. TriCBs, TetraCBs, and DiCBs were found to be most abundant. Concentration of dioxins contamination in two samples is 650-670 ngTEQ g⁻¹, of which 69-71 ngTEQ g⁻¹ from PCDD/Fs with the predominant congeners of 1,2,7,8-TeCDF; 2,3,7,8-TeCDF; 2,3,4,7,8-PeCDF and 1,2,3,7,8-PeCDF. The contributions of DL-PCBs in total TEQ in both samples were more than 85%. The dioxin-like toxicity in insulating oils contained in electrical capacitors could be considered receive attention as an important dioxins source if such wastes are not managed in an environmentally sound manner.     

Identification and quantification of products formed via photolysis of decabromodiphenyl ether

Background, aim, and scope  Decabromodiphenyl ether (DecaBDE) is used as an additive flame retardant in polymers. It has become a ubiquitous environmental contaminant, particularly abundant in abiotic media, such as sediments, air, and dust, and also present in wildlife and in humans. The main DecaBDE constituent, perbrominated diphenyl ether (BDE-209), is susceptible to transformations as observed in experimental work. This work is aimed at identifying and assessing the relative amounts of products formed after UV irradiation of BDE-209. Materials and methods  BDE-209, dissolved in tetrahydrofuran (THF), methanol, or combinations of methanol/water, was exposed to UV light for 100 or 200 min. Samples were analyzed by gas chromatography/mass spectrometry (electron ionization) for polybrominated diphenyl ethers (PBDEs), dibenzofurans (PBDFs), methoxylated PBDEs, and phenolic PBDE products. Results  The products formed were hexaBDEs to nonaBDEs, monoBDFs to pentaBDFs, and methoxylated tetraBDFs to pentaBDFs. The products found in the fraction containing halogenated phenols were assigned to be pentabromophenol, dihydroxytetrabromobenzene, dihydroxydibromodibenzofuran, dihydroxytribromodibenzofuran, and dihydroxytetrabromodibenzofuran. The PBDEs accounted for approximately 90% of the total amount of substances in each sample and the PBDFs for about 10%. Discussion  BDE-209 is a source of PBDEs primarily present in OctaBDEs but also to some extent in PentaBDEs, both being commercial products now banned within the EU and in several states within the USA. It is notable that OH-PBDFs have not been identified or indicated in any of the photolysis studies performed to date. Formation of OH-PBDFs, however, may occur as pure radical reactions in the atmosphere. Conclusions  Photolysis of decaBDE yields a wide span of products, from nonaBDEs to hydroxylated bromobenzenes. It is evident that irradiation of decaBDE in water and methanol yields OH-PBDFs and MeO-PBDFs, respectively. BDE-202 (2,2′,3,3′,5,5′,6,6′-octabromodiphenyl ether) is identified as a marker of BDE-209 photolysis. Recommendations and perspectives  BDE-209, the main constituent of DecaBDE, is primarily forming debrominated diphenyl ethers with higher persistence which are more bioaccumulative than the starting material when subjected to UV light. Hence, DecaBDE should be considered as a source of these PBDE congeners in the environment. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

PCDDs, PCDFs, dioxin-like PCBs and indicator PCBs in soil from five selected areas in Slovakia

There is a lack of information regarding persistent organic pollutants (POPs) in soil from Slovakia. This paper reports the concentrations of 17 polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), 12 dioxin-like polychlorinated biphenyls (dl-PCBs) and 6 indicator PCBs associated with 32 soil samples collected in 2007 from areas in the vicinity up to several kilometres from four selected industrial PCDD/F sources in Slovakia and one background area.The results show that the total WHO₁₉₉₈-PCDD/F/dl-PCB-TEQ concentrations varied from 0.34 to 18.05 pg g⁻¹ dry weight (dw) and the average total TEQ concentrations in samples collected at the Šala, Košice, Krompachy and Dubová areas were 3.18, 2.64, 7.80, and 3.19 pg g⁻¹ dw respectively. The average of the total WHO₁₉₉₈-TEQ values in three soil samples representing the background Starina area was 0.66 pg g⁻¹ dw. The predominant contaminants among 2,3,7,8-substituted PCDD/Fs, dl-PCB, and indicator PCBs was OCDD, PCB 118, and PCB 153 respectively. The major contributors to the TEQ were 2,3,4,7,8-PeCDF, PCB 126, 1,2,3,7,8-PeCDD, PCB 156 and 1,2,3,4,7,8-HxCDF + 1,2,3,4,7,9-HxCDF in descending order.     

PCDD/PCDF,chlorinated pesticides and PAH in Chinese teas

Four samples of Chinese tea (two green teas, and two brick teas) were analyzed for their concentrations of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/PCDF), chlorinated pesticides and PAH. The infusions prepared from these teas were also analyzed for PCDD/PCDF. The levels of DDT and its metabolites in tea leaves were within the safety limit of 0.2 mg/kg. Rather high levels of total PAH were obtained in brick tea (1048–1162 mg/kg), when compared with green tea (497–517 mg/kg). In terms of PCDD/PCDF, the concentrations of green tea and brick tea differed by a factor of 16, while the concentrations of all infusions were within a factor of 2. The dioxin concentrations in green tea leaves can be explained through uptake of atmospheric PCDD/PCDF. The higher concentrations in the brick tea leaves are due the longer exposure time, and to certain extent, the use of old leaves, branches and roots when making the tea, and additional components such as soil particulates through contamination. Certain Chinese populations drinking a large amount of brick tea (>3 l per day) indicated that individuals of these populations consume more tea than Europeans or North Americans result in a comparably higher intake of PCDD/PCDF. Tea consumption can attribute to up to 10% of the TDI recommended by WHO (only PCDD/PCDF considered, no PCB analyzed).     

Soxhlet extraction parameters’ influence on the recovery of polychlorinated dibenzo‐p‐dioxins and dibenzofurans (PCDD/F) from a sediment,and artifact formation of PCDD

Soxhlet extraction of polychlorinated dibenzo‐p‐dioxins/dibenzofurans (PCDD/F) from sediment was studied using a designed experimental set‐up. Three variables were studied: three solvent combinations n‐hexane/methanol, dichloromethane/acetone and toluene/methanol; two extraction times, 8 and 16 h, and addition of bulk substances (sodium carbonate). The extraction efficiency was almost identical in all extractions, with the exception of extraction where toluene/ methanol was combined with sodium carbonate. In these samples a major effect was observed, due to formation of Hx‐, Hp‐ and OCDD isomers. Composition of formed PCDD was similar to PCDD isomers found in pentachlorophenol products.     

六六六热解废渣中2,3,7,8—取代PCDDs和PCDFs的测定

采用ＨＰＬＣ和ＧＣ／ＭＳ法对六六六热解废渣中的ＰＣＤＤｓ和ＰＣＤＦｓ进行了测定，使用此种方法，于废渣中检出了所有２，３，７，８－取代的同系物。此外，还根据各ＣＤＤｓ，ＣＤＦｓ的毒性当量因子ＴＥＦｓ，计算了废渣的毒性当量ＴＥＱｓ，约为６１２－９２４μｇ／ｇ。分析表明，ＯＣＤＤ是含量最丰富的导构体，而１，２，３，４，６，７，８－ＨｐＣＤＤ，１，２，３，４，６，７，８－ＨｐＣＤＦ和１，２，３，４，７，８