定位拓扑指数与多氯联苯溶解度、分配系数的定量关系

通过定义并计算多氯联苯（PCBs）及其原子的特征值，采用分子图形学技术获得了定位拓扑指数和基团对应指数．基于多元回归方法构建了对PCBs溶解度和正辛醇／水分配系数进行估算的定量结构-活性相关关系，得到了二元回归方程，估算的平均误差分别为0．12和0．34．利用方程对另外7个PCBs分子的溶解度和正辛醇／水分配系数进行预测，预测值和实验值的一致性令人满意．     

Fast isolation of hydrophobic organic environmental contaminants from exposed semipermeable membrane devices (SPMDs) prior to GC analysis

Semipermeable membrane devices (SPMD) represent a passive sampling technology that is becoming widely used for monitoring of surface waters pollution. While "classic" procedures employ dialysis to recover target compounds from exposed SPMDs, in the present study analytes were isolated from cut membrane together with sequestering medium (triolein) using hexane as an extraction solvent. This approach allowed us to reduce the time needed for accomplishment of isolation step from 48 h to only 1 h. Automated gel permeation chromatography (GPC) clean-up is employed in the following step to separate triolein from analytes fraction. Musk compounds (MCs), polychlorinated biphenyls (PCBs), brominated flame retardants (BFRs) and several other persistent organochlorine compounds (OCs) were determined in the respective fraction by GC method employing selective detectors (MSD, ECD). As shown in a series of analyses of SPMDs deployed in various aquatic ecosystems, high recoveries and good repeatability of results together with a possibility to obtain the information on the pollution of sampling site at the day of sample arrival to laboratory make this newly implemented procedure an interesting alternative to time consuming dialysis.     

多氯联苯的正辛醇-空气分配系数与气相色谱保留参数的关联

通过对19种多氯联苯（PCBs）在DB-1,DB-5和DB-1701等3种色谱柱上的气相色谱（GC）保留参数A,B值与正辛醇-空气分配系数(Koa)的相关分析,发现GC保留参数A,B与Koa存在明显的线性关系。采用了逐步回归的方法,建立了保留参数A,B与Koa的二元回归方程,相关系数的平方达到了0.99以上,标准偏差小于0.11。此外,根据实验测定的153个PCBs的GC保留参数以及定量构效关系（QSAR）研究中的56个预测值,对剩余190种PCBs的Koa值进行了预测。     

Diol sep-pak cartridges for enrichment of polychlorobiphenyls and chlorinated pesticides from water samples; determination by GC-ECD

Summary Gas chromatography of polychlorinated biphenyls and chlorinated pesticides in water samples has been performed after adsorption from a 20–200-mL sample on to a cartridge containing 100 mg diol-bonded porous silica. The PCBs are desorbed with 500 μL ethyl acetate, which is concentrated and analysed by gas chromatography with electron-capture detection (GC-ECD). The average recovery of 0.1 ng mL⁻¹ PCB congeners from distilled water and from Aniene river water is≥95% (standard deviation≤2.8). Average recoveries of 25 ng mL⁻¹ Aroclor 1254 from distilled water and from Aniene river water were, respectively, 94.4% and 92.5% (standard deviation 5.8). In the separation of PCB congeners from the chlorinated pesticides only the aldrin (40%) was eluted with the PCBs from the diol Sep-Pak cartridge by aqueous methanol. The method described is simple and reproducible.     

Extensive study on physicochemical properties of polychlorinated biphenyls in a commercial ion trap mass spectrometer,relevance in analytical and environmental chemistry

Polychlorinated biphenyls (PCBs) exist as 209 congeners, consisting of biphenyl molecules, where the number and substitution positions of halogen atoms are known to affect industrial uses, environmental transport mechanisms, distribution, fate, and toxicity. The complexity of the problem requires accurate physicochemical studies of an increasing number of congeners in order to understand the environmental and biological processes at play. This work presents a systematic study on the thermodynamic and kinetic properties of PCBs by quadrupole ion trap mass spectrometry. A clear relationship between structure and behavior of PCBs in mass spectrometry experiments has been observed. Overall data demonstrate that di‐ortho congeners show lower thermodynamic stability and higher fragmentation rate than non/mono‐ortho. Congeners follow different fragmentation mechanisms according to the number of chlorine atoms in ortho position of the biphenyl system. Experimental kinetic curves of mono/non‐ortho and di‐ortho congeners show a strong similarity with classical first‐order kinetics curves; in particular, di‐ortho congeners follow a first‐order consecutive reaction, while mono/non‐ortho follow a first‐order parallel reaction. For each studied congener, the kinetic constant of reaction (fragmentation) has been determined. Data support environmental levels and biochemical transformations described in literature. The general picture of the PCB behavior inside a quadrupole ion trap provides the basis for the development of reliable and cost‐effective analytical methods to the determination of ultra‐low level trace of PCB congeners.     

A QSRR Study on the Chromatographic Retention Indices of Hydroxylated Polychlorinated Biphenyls

Hydroxylated Polychlorinated Biphenyls (HO-PCBs) are the metabolite of polychlorinated biphenyls and have drawn much attention because they have hazard on human health and ecosystems. Molecular connectivity index calculation has been performed for 19 HO-PCB compounds. A number of statistically based parameters have been extracted. Linear relationship between chromatographic retention index (RI) and the molecular connectivity index of 15 compounds in the training set has been established by multiple linear regression method. The other 4 HO-PCBs are used as the external test set. The result shows that the parameters can be well used to express the quantitative structure-retention relationship (QSRR) of HO-PCBs. Good stability and predictive ability have been demonstrated by leave-one-out cross-validation and the external test set.     

Occurrence of organochlorine pesticides and polychlorinated biphenyls in soils and sediments from Eastern Romania

Polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs), such as DDT and analogues, hexachlorocyclohexane (HCH) isomers and hexachlorobenzene (HCB), were measured in surface soils and sediments from Eastern Romania. Thirty-nine soil samples from the forested zone, eight soil samples from a municipal waste-disposal site, and 10 sediment samples from the Bahlui River along the Iassy city were analysed using accelerated solvent extraction (ASE) and gas chromatography coupled to electron capture detection or mass spectrometry. The low mean concentrations of OCPs (11–31 and 22–84?ng?g^?1 for HCHs and DDTs, respectively) and PCBs (8–43?ng?g^?1) in soil samples from the forested zone suggest that contamination at most of these sites occurred predominantly through atmospheric transport from zones where these compounds were used and subsequently through atmospheric deposition. Contrarily, soil samples collected in the vicinity of a waste-disposal site near Iassy contained higher mean levels of PCBs (278?ng?g^?1, range 34–1132?ng?g^?1) than OCPs (6 and 101?ng?g^?1 of soil for HCHs and DDTs, respectively). The sediment samples collected along the Bahlui river throughout the Iassy city revealed higher mean levels of PCBs (59?ng?g^?1, range 24–158?ng?g^?1) compared with OCP levels (2 and 37?ng?g^?1 of soil for HCHs and DDTs, respectively). Furthermore, PCB profiles and concentrations in the sediment samples varied considerably along the river due to a wide variety of sources, such as different industries and waste sites. Although their sources are difficult to evaluate, the presence of POPs at most sites (especially at the waste-disposal site) may constitute a potential health hazard.     

Solid phase extraction with silicon dioxide microspheres for the analysis of polychlorinated biphenyls in environmental water samples prior to gas chromatography with electron capture detector

This paper describes a simple, rapid and sensitive method for the determination of polychlorinated biphenyls (PCBs) including PCB-28, PCB-52, PCB-101, PCB-138, PCB-153 and PCB-180 using silicon dioxide microspheres solid phase extraction cartridge prior to gas chromatography with electron capture detector. The experimental results indicate that there were excellent linear relationships between the peak areas and the concentrations of polychlorinated biphenyls, and the linear ranges were in the concentration range of 0.1 to 30?µg?L^?1 with the correlation coefficients in the range of 0.9962 to 0.9998. The detection limits were in the range of 0.003 to 0.019?µg?L^?1. The precisions of the proposed method were below 10% (n?=?6). The enrichment factors, described as the ratio of the slope of the calibration curves with and without extraction, were in the range of 605.2 to 1414.6. The proposed method was used to analyse the real water samples, and satisfactory spiked recoveries in the range of 80 to 117% were achieved. These results demonstrated that silicon dioxide microspheres without modification were good adsorbent for the enrichment of polychlorinated biphenyls and the developed method were of great value and would be a good alternative for the routine analysis of polychlorinated biphenyls in the future.