Polychlorinated Organic Compounds Research Articles

Characterization of Compound-Specific Chlorine Isotopologue Distributions of Polychlorinated Organic Compounds by GC-HRMS for Source Identification.

Distributions of chlorine isotopologues are potentially a fingerprint feature of organochlorines. However, the exact distributions remain little known. This study measured compound-specific chlorine isotopologue distributions of six polychlorinated organic compounds (POCs) for source identification. Complete chlorine isotopologues of POCs were detected by gas chromatography coupled to high-resolution mass spectrometry. The measured relative abundances (Ameas), theoretical relative abundances (Atheo), and relative variations between Ameas and Atheo (ΔA) of chlorine isotopologues were determined. These ΔA values were applied to characterize differences in isotopologue distribution patterns, and the ΔA patterns directly illustrated the distribution characteristics. Perchloroethylene (PCE) and trichloroethylene (TCE) from two manufacturers were chosen as model analytes to develop and validate the analytical method, including precision, concentration dependency, and temporal drift. The ΔA values of isotopologues of the PCE and TCE chemicals were from -82.5 to 19.9‰ with standard deviations (SDs) of 0.3-16.9‰. In addition, the ΔA values of the first three isotopologues (with 0-2 37Cl atoms) were from -15.5 to 19.9‰ with SDs of 0.3-1.6‰, showing sufficient precisions. No concentration dependency and temporal drift of ΔA were observed. The method has been successfully applied to source identification for PCE and TCE in commercial chemicals and plastic materials, and four polychlorinated biphenyls in chemicals and sediments, demonstrating that the ΔA values and ΔA patterns were discernable for POCs from different sources. This study demonstrates that compound-specific chlorine isotopologue distributions of POCs are differentiable and measurable, proposing a novel approach to perform fingerprinting analysis for the distributions, which is anticipated to facilitate source identification for organochlorine pollutants.

Are chlorine isotopologues of polychlorinated organic pollutants binomially distributed? Theoretical evaluation, numerical simulation, experimental evidences and implications for chlorine isotope analysis and source identification

Relative abundances of chlorine isotopologues of polychlorinated organic compounds (POCs) are commonly recognized to comply with binomial distribution. This study investigated whether chlorine isotopologue distributions of polychlorinated organic pollutants are binomial and evaluated implications of the distributions to relevant analytical and environmental research by theoretical derivation, numerical simulation and experiment. Chlorine kinetic isotope effects and equilibrium isotope effects vary in stepwise chlorination reactions, leading to inconsistent chlorine isotope ratios on different reaction positions of products, which results in non-binomial chlorine isotopologue distributions of the products. After physical changes and dechlorination, chlorine isotopologues of POCs are unlikely binomially distributed. The experimental results demonstrated that the chlorine isotopologue distributions of perchloroethylene, trichloroethylene, methyl-triclosan, and 2,3,7,8-tetrachlorodibenzofuran in standards and four polychlorinated biphenyls in both standard solutions and sediments were non-binomial. The patterns of chlorine isotope ratios derived from pairs of neighboring chlorine isotopologues of POCs from different sources were different, implying different isotopologue distributions, which might cause biases in compound-specific isotope analysis of chlorine (CSIA-Cl) and source identification. A complete-isotopologue scheme for isotope ratio calculation is recommended to CSIA-Cl for obtaining accurate data. Gas chromatography-double focusing magnetic-sector high resolution mass spectrometry is a promising instrument for CSIA-Cl that uses the complete-isotopologue scheme due to its excellent sensitivity, selectivity and ruggedness. This study yields new insights into chlorine isotopologue distributions of polychlorinated organic pollutants and proposes practicable solutions to improve CSIA-Cl that uses gas chromatography-mass spectrometry and facilitate source identification of polychlorinated organic pollutants.

Forms and pathways of migration and transformation of hazardous chemicals in the environment

The forms of existence, pathways of migration, and mechanisms of transformation of polychlorinated organic compounds (POCs) and polyaromatic hydrocarbons (PAHs) in the aqueous medium are analyzed. For 2,4,5-trichlorophenol, as an example, a free-radical mechanism of the formation of polychlorinated dibenzofurans and dibenzodioxins during the direct photolysis of POCs has been established. For benzo[a]pyrene, as an example, the role of OH radicals in the oxidation of PAHs sorbed on organomineral sorbents by singlet oxygen has been revealed. The role of monosulfide complexes of Fe(II) and 1: 1 monothiolate complexes of Cu(I) in the formation of a quasi-reducing state of the natural aquatic environment, toxic for aerobic organisms with intensive water exchange, has been elucidated, a state in which copper ions become biologically inaccessible.

MODIFIED ANT COLONY OPTIMIZATION ALGORITHM AND ITS APPLICATION IN VARIABLE SELECTION OF QSAR OF POLYCHLORINATED ORGANIC COMPOUNDS

A modified ant colony optimization (ACO) algorithm was used for the selection of the variables that result in the best-fitted models for the bioconcentration factor (BCF) of polychlorinated organic compounds (PCOCs). The fitness function of the modified ACO is discussed in detail and a new expression for the fitness function is presented. The modified ACO is applied in quantitative structure–activity relationships of selected PCOCs for predicting BCFs and the best-fitting models by the ACO were obtained. The convergence velocity was acceptable.

Evaluation of Organic Environmental Pollutants Detected in Human Milk

Human milk is an important food source for infant because it contains a large number of nutritional substances, growth and immune factors. However, human milk may be contaminated with environmental pollutants when mothers are exposed to these pollutants. In particular, lipophilic organic pollutants are likely to accumulate in milk fat. Therefore, the determination of the organic pollutants levels in human milk is necessary to estimate the health risks of these pollutants to milk-fed infants. For this purpose, a lot of reports for the measurements of environmental pollutants in milk samples have been published. In this review, we summarized the concentrations of harmful organic environmental pollutants such as polychlorinated organic compounds (PCOCs), polybrominated compounds, perfluorinated compounds (PFCs), polycyclic aromatic hydrocarbons (PAHs) and endocrine disrupting phenols in human milk samples. Also, we described the noteworthy results of several evaluative studies such as time trend and regional difference of pollutant levels.

PARTITION PROPERTIES OF 18 POLYCHLORINATED ORGANIC COMPOUNDS (PCOCs): CORRELATION WITH MOLECULAR STRUCTURAL DESCRIPTORS

The capacity factors (k′) were determined by reversed phase high-performance liquid chromatography (RP-HPLC) on C18 column for 18 polychlorinated organic compounds (PCOCs). Quantum chemical parameters and linear solvation energy descriptors were calculated for the tested chemicals and used to develop quantitative structure property relationships (QSPR). Results demonstrated that the quantum chemical parameters could be used to predict k′ and n-octanol/water partition coefficients (Kow) for the test compounds, and the RP-HPLC was a simple and reliable method for prediction of Kow.

PARTITION PROPERTIES OF 18 POLYCHLORINATED ORGANIC COMPOUNDS (PCOCs): CORRELATION WITH MOLECULAR STRUCTURAL DESCRIPTORS

The capacity factors (k′) were determined by reversed phase high-performance liquid chromatography (RP-HPLC) on C18 column for 18 polychlorinated organic compounds (PCOCs). Quantum chemical parameters and linear solvation energy descriptors were calculated for the tested chemicals and used to develop quantitative structure property relationships (QSPR). Results demonstrated that the quantum chemical parameters could be used to predict k′ and n-octanol/water partition coefficients (Kow) for the test compounds, and the RP-HPLC was a simple and reliable method for prediction of Kow.

Trace analysis of dissolved polychlorinated organic compounds in the water of the Yangtse River (Nanjing, China)

Eighteen organochlorine contaminants from the water samples of the Yangtse River have been qualitatively and quantitatively analyzed. The analysis of polychlorinated organic compounds (PCOCs) extracted by C18 Solid Phase Extract (SPE) was performed using HP6890 gas chromatograph coupled by ECD detector. The analytical results demonstrate that the analytical methods are reliable based on the fact that most of the recoveries for the targeted compounds are 60–90%. Most of the concerned contaminants, i.e. chlorinated pesticides and PCBs were found in the water samples of the Yangtse River, but their concentration was very low, <2.97 ng l −1, which is far less than 1 μg l −1 — the standard of drinking water of China. It is apparent that the PCOCs were in high concentration during the dry season, and in low concentration during the rainy season. The situation of PCOCs contamination in the water of the Yangtse River in 1999 was greatly improved in comparison with 10 years ago.

Progressive study and robustness test of QSAR model based on quantum chemical parameters for predicting BCF of selected polychlorinated organic compounds (PCOCs)

Systematic analyses on the effects of chemical structures of 31 polychlorinated organic compounds (PCOCs) on their bioconcentration behavior in rainbow trout ( Oncorhynchus mykiss) were conducted using quantitative structure–activity relationship (QSAR) techniques. The cluster analyses of individual variables as well as the quality control chart of QSAR model implies the existence of outliers, while the simulation model excluding such samples showed an extreme robustness even if it was tested with different methods. Furthermore, the quantum chemical parameters entering into QSAR model were used to describe the bioconcentration pathways, and the results indicated that bioconcentration behaviors of selected compounds were complicated processes involving permeation stages as well as bio-chemical reaction stages.

Polychlorinated organic compounds in Yangtse River sediments

Polychlorinated organic compounds (PCOCs) were analyzed in Yangtse River sediments. The results show that the concentrations of PCOCs in Yangtse River sediments followed the order of DDTs > HCB > HCHs > PCBs. High PCOCs concentrations were detected in sediments from station Y02a and Y02b, which are located in the main input of the Yangtse River (Nanjing section). Results also show that the PCOCs values were highly correlated with organic carbon content and heavy metal contamination.

Polychlorinated organic compounds (PCOCs) in waters, suspended solids and sediments of the Yangtse River

The contamination levels of polychlorinated organic compounds (PCOCs) in waters, suspended solids and sediments of the Yangtse River (Nanjing part) were analyzed in this paper. Their concentrations determined by GC/MS were very low in comparison with those in European River. The average concentration of total HCH (α-HCH, β-HCH, γ-HCH) was much higher than that of other PCOCs in all waters, which made up 65% of total amount of PCOCs. Due to the complete dilution and mixture of pollutants in the mighty Yangtse River, the content of PCOCs at each sampling station demonstrated very similar spatial pattern for waters and suspended solids. Since the small suspended solid (<0.7 μm) passed through the filter was also considered as dissolved part, the dominant parts of HCHs, PCA and PCBs were found in dissolved phase with percentage proportion of 85–94%, 72–85% and 61–78%, respectively. For DDTs, HCB and PeCB, their contents in dissolved phase were slightly higher than in particulate phase. The contents of PCOCs in sediments were also very low and varied with high fluctuation at different sampling points, indicating the heterogeneous deposition. HCB and its metabolite (PeCB) presented the highest contamination levels among PCOCs in sediments.

Polychlorinated organic compounds (PCOCs) in the Yangtse River water samples using SPE and GC/ECD.

Polychlorinated organic compounds (PCOCs) in the Yangtse River water samples using SPE and GC/ECD.

Polychlorinated organic compounds in the Arctic cod liver: trends and profiles

Polychlorinated organic compounds (POCs) have been measured in Arctic cod liver from Vestertana Fjord for a period of 1987–1998. Significant decrease was observed for DDD ( p=0.043), α-HCH ( p=0.001), and γ-HCH (lindane; p=0.001). Contents of DDE, 2,3,7,8-tetrachlorodibenzofuran, PCBs, chlordanes, chloronaphthalenes, hexachlorobenzene and polychlorodiphenyl ethers had no significant trend. Contents of three hexa- and two heptachlorodibenzofurans and octachlorodibenzofuran increased slightly from 1987 to 1994, but then at very high rate from 1994 to 1998. Trends of HCHs, profiles of PCBs and levels of chlordanes are in accordance with atmospheric long range transport. The hexa-, hepta- and octachlorodibenzofurans observed are major impurities in chlorophenol formulation Ky-5, which has been used as wood preservative and as fungicide/slimicide in industrial processes. Their profile in Vestertana cod was similar to that observed in Ky-5 contaminated fish.

Factors that influence the level of contamination of human milk with poly-chlorinated organic compounds

Polychlorinated organic compounds (POCs) accumulate in tissues with a high fat content. Nursed babies are exposed to POCs through the fat in human milk. Exposure levels are estimated to exceed those considered acceptable as a lifelong daily dose. Nevertheless, mothers are still positively advised as to breast-feeding. In 1988, a survey on contamination of human milk with POCs was carried out in The Netherlands. Levels of ten different organochlorine pesticides (OCPs), eight polychlorinated biphenyl (PCB) congeners, and seventeen polychlorinated dibenzodioxin (PCDD) and -dibenzofuran (PCDF) congeners were determined by use of gaschromatographic techniques with either electron-capture or mass-spectrometric detection. Information on some factors potentially influencing the level of contamination of human milk was obtained by questionnaires. The estimated response amounted to 71 percent. Regression analysis was used to investigate associations between determining factors and specific contaminants. It appeared that maternal age was positively associated with POC concentrations. Traditional omnivorous diet was associated with lower concentrations of POCs when compared to all other types of diet. The post-pregnancy Quetelet Index [by definition calculated as weight/(length)2] and the cumulated period of previous breast-feeding were negatively associated with POC concentrations. In conclusion, chemical behavior and environmental distribution patterns of the POCs measured in this study, if translated to factors of human exposure, are in accordance with the study results. Exposure levels will decrease if emissions can be further reduced. Still, in the near future, maternal age will probably rise (Vermunt 1992; Netherlands Central Bureau of Statistics 1992), whereas the duration of lactation in expected to decline. Consequently, there might be an increase in average POC-concentrations in human milk in the forthcoming years.

Factors that Influence the Level of Contamination of Human Milk with Poly-chlorinated Organic Compounds

Factors that Influence the Level of Contamination of Human Milk with Poly-chlorinated Organic Compounds