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51.
52.
Moreno Frías M Jiménez Torres M Garrido Frenich A Martínez Vidal JL Olea-Serrano F Olea N 《Biomedical chromatography : BMC》2004,18(2):102-111
A study was undertaken to determine the extent of organochlorine pesticide (OP) and polychlorinated biphenyl (PCB) contamination in infant formula milk and in the human milk, fat and serum of women from an agricultural area in Southern Spain. A procedure is proposed that simultaneously detects trace levels of lindane, endosulfan-ether, vinclozolin, aldrin, endosulfan-lactone, endosulfan-alpha, 4,4'DDE, 2,4'DDT, endosulfan-beta, 4,4'DDT, kepone, endosulfate-sulfate, methoxychlor, mirex, 2,3,4 PCB, 2,2',4,5 PCB, 2,3,4,5 PCB and 2,2',3,3',6,6'PCB. After liquid-liquid or solid-liquid extraction, the extract of the sample was cleaned by high performance liquid chromatography (HPLC) and the fi rst eluted fraction was analysed by gas chromatography (GC) with mass spectrometry (MS) detector in tandem mode. To evaluate the validity of the method the following parameters were studied: linearity, detection limits, quantification limits, specificity, percentage recovery and precision. A study of the uncertainty associated with the analytical method was also carried out. 相似文献
53.
随机选择空白的和经过印刷的新闻纸和复印纸 ,粉碎后用溶剂提取并经多步色谱柱纯化 ,采用同位素稀释、高分辨气相色谱 /高分辨质谱 (HRGC/HRMS)联用技术分析了其中的二含量。结果表明 :新闻纸中二的总量高于复印纸 ,但是毒性当量却低于复印纸 ;经过印刷的新闻纸和复印纸中二的含量均高于空白的新闻纸和复印纸 ;新闻纸和复印纸中相同二异构体的含量是不同的。空白的和经过印刷的新闻纸中二毒性当量分别为 0 4 8ng/kg和 0 6 1ng/kg,而空白的和经过印刷的复印纸中二毒性当量分别为 0 74ng/kg和 0 79ng/kg。所有样品中添加的13 C标记的 2 ,3,7,8位取代的二回收率均在 4 9 82 %至 131 34%之间。 相似文献
54.
定位拓扑指数与多氯联苯溶解度、分配系数的定量关系 总被引:3,自引:0,他引:3
堵锡华 《武汉大学学报(理学版)》2007,53(2):151-154
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. 相似文献
55.
多氯联苯系列化合物的热力学性质和稳定性的密度泛函理论研究 总被引:9,自引:1,他引:8
在B3LYP/6-31G*水平上计算了218个多氯联苯系列化合物(PCB), 得到分子总能量(ET)、焓(H°)、熵(S°)、自由能(G°)、零点振动能(EZPV)、恒容热容(CV°)和热能校正值(Eth), 研究了这些参数与氯原子的取代数目及取代位置的关系.氯原子置换在不同的位置使ET, H°和G°数值增加的顺序为: 2(6)位>>3(5)位>4位, 即置换在2(6)位最不稳定; 两个氯原子在同一苯环比分别处于两个苯环的ET, H°和G°增大, 增加的顺序为: 邻位>>间位>对位, 即相互处于邻位最不稳定. 每增加1个氯原子, S°增大约30 J•(mol•K)-1, Eth减小约22.2 kJ•mol-1, EZPV减小约25.5 kJ•mol-1, CV°增大约16 J•(mol•K)-1. 根据异构体自由能的相对大小, 从理论上求得异构体的相对稳定性顺序. 相似文献
56.
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 总被引:2,自引:0,他引:2
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。 相似文献
57.
58.
《Journal of mass spectrometry : JMS》2017,52(12):837-847
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. 相似文献
59.
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. 相似文献
60.
Qingxiang Zhou Wei Wu Junping Xiao 《International journal of environmental analytical chemistry》2013,93(8):894-905
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. 相似文献