Novel estimation of lipophilic behaviour of polychlorinated biphenyls (original) (raw)
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Chemosphere, 1995
Abstract The ability of the Characteristic Root Index (CRI) to predict the n-octanol/water partition coefficients (Kow) of polychlorinated biphenyls (PCBs) has been demonstrated. The CRI for 58 congeners were calculated from the roots of the characteristic polynomial obtained from a square matrix comprising all possible orders of valence connectivity index — except zero order — for a congener as the entry. The correlation proposed for the estimation of Kow of PCBs based on the CRI model contains only one variable and predicts log Kow with high regression coefficient (r=0.998) and may be regarded satisfactory for environmental applications. Copyright © 1995 Published by Elsevier Ltd.
Chemosphere, 1994
The ability of the UNIFAC group-contribution model to accurately predict aqueous solubility (S), 1octanol/water partition coefficient (Kow) and Henry's law constant (HLC) for polychlorinated biphenyls PCBs) was evaluated by comparing experimental values of S, Kow and HLC with those estimated using UNIFACderived activity coefficients. Five different sets of interaction parameters tables were evaluated along with two previously published regression equations designed to correct for systematic errors. The best estimates of S, Kow and HLC were obtained using vapor-liquid equilibrium (VLE)-based parameter table published in 1982 by Gmehling et al., with modified values for aromatic chlorine and water interaction parameters. 657 Literature Cited
Solubility of polychlorinated biphenyls in water/alcohol mixtures. 1. Experimental data
Environ Sci Technol, 1994
The solubilities of 4-monoch1orobipheny1, 2,4,6-trichlorobiphenyl, and 2,2',4,4',6,6'-hexachlorobiphenyl in mixtures of water and n-alcohols were measured using batch equilibrium techniques. The n-alcohols have carbon numbers ranging from one to eight. Measurements were made over a wide range of alcohol concentrations. The presence of methanol, ethanol, and l-propanol enhances the aqueous solubility of the solutes, and the degree of enhancement increases with increasing hydrophobicity of both solute and alcohol. Deviations from a log-linear relationship were observed. Partially water-miscible alcohols (l-butanol, l-pentanol, l-hexanol, l-heptanol, and l-octanol), when saturated in water, tend to exert smaller effects on the solubility of solutes as the alkyl chain of the alcohols becomes longer. Equations were obtained through regression of the experimental solubility with the volume fraction of alcohol. These equations can be used to predict the solubility of the PCB congeners in mixtures of water and alcohols.
Chemosphere, 1992
A novel method is presented for the analysis of coplanar (i.e. non-ortho substituted) polychlorinated biphenyls (PCBs) in environmental samples. The new procedure combines methylene chloride extraction, gel permeation and Florisil chromatography. Recovery efficiencies and resolution of the Florisil column method are reported and compared to the carbon column method. It is shown that both the Florisil column and the Carbon column techniques give comparable results with recovery efficiencies for PCBs 77, 126 and 169 of nearly 100%. Excellent resolution and reproducibility for quantitative analysis of coplanar PCBs are obtained in complex PCB mixtures. The Florisil method is considerably simpler than the carbon column technique and better suited for routine analysis.
Application of correlation analysis for identification of polychlorinated biphenyls
Journal of Chromatography A, 1996
The analytical process was optimized for the determination of individual PCBs in a commercial mixture, Delor 104, and in soil samples contaminated by PCBs. The optimal analytical conditions for the GC-MS system with a DB-5 capillary column involved a temperature program evaluated in terms of information content I(S) and information flow l(S)/t and an identification procedure based on the correlation analysis of the measured and published relative retention r~2 data.
Meta-heuristics on quantitative structure-activity relationships: study on polychlorinated biphenyls
Journal of Molecular Modeling, 2010
A genetic algorithm was developed and assessed in order to select pairs of proper structural descriptors able to estimate and predict octanol-water partition coefficients of polychlorinated biphenyls (PCBs). The molecular descriptors family was calculated for a sample of 206 PCBs. The problem of searching for the proper descriptors in order to identify structure-activity relationships was translated in genetic terms. The following parameters were imposed in the genetic algorithm (GA) search: sample size − 12, number of variables in multivariate linear regression − 4, imposed adaptation requirements − 3 criteria, maximum number of generations − 50,000, selection strategy − tournament, probability of parent/child mutation − 0.05, number of genes implied in the mutation − 2, optimization parameter - determination coefficient, optimization score - minimum in the sample, and optimization objective - maximum. The highest determination coefficient was obtained in the generation 17,277. Twenty-one evolutions were studied until the optimum solution was obtained. The model identified by the implemented genetic algorithm proved not to be statistically different from the model identified through complete search (ZSteiger = 1.37, p = 0.0861). According to this GA model, the relationship between the structure of PCBs and octanol-water partition coefficients was of geometric and topological nature as previously revealed by the complete search. The genetic algorithm proved its ability to identify two pairs of molecular descriptors able to characterize the relationship between the structure of PCBs and the octanol-water partition coefficient.
Modern approaches in separation, identification and quantification of polychlorinated biphenyls
Current Opinion in Environmental Science & Health, 2020
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