Selected PCB Congeners Research Articles

Gas chromatographic separation of PCB atropisomers on cyclodextrin stationary phases

Gas chromatographic study on chiral separation of PCBs was performed in a series of capillary columns coated with 0.1-μm film of modified cyclodextrin (CD) stationary phases. The preparation of columns included the investigation into the effect of the content of cyclodextrin derivative in polysiloxane, the type of polysiloxane and temperature of analysis on the quality of separation and retention of atropisomers of 15 selected PCB congeners. The separation properties towards PCBs of stationary phase heptakis(2,3-di-O-methyl-6-O-tert-butyl-dimethylsilyl)-β-CD dissolved in SE-30, SE-54, and OV-1701, were compared with those of 6-monokis-octamethylene-permethyl-β-CD anchored to polydimethylsiloxane polymer (ChirasilDex column, Chrompack, Middelburg, The Netherlands) and octakis(2,6-di-O-methyl-3-O-pentyl)-γ-CD in OV-1701 (MEGA, Legnano (MI), Italy). The correctness of quantitative enantiomer ratio determination was assesed by splitless analysis of PCBs reference solutions in concentration of 1.25–125 ng/ml (PCBs 45 and 91) and 2.5–250 ng/ml (PCB 95) (the PCB congeners are numbered according to IUPAC). Chirality 10:540–547, 1998. © 1998 Wiley-Liss, Inc.

LOCALIZED ENRICHMENT OF PCB LEVELS IN STREET DUST DUE TO REDISTRIBUTION BY WIND

As part of a project to identify PCB sources in combined sewer overflows discharging to the Buffalo River, NY, nine street and two unpaved aggregate parking lot dust and dirt samples were collected and analyzed for selected PCB congeners and total PCBs. Without exception, the dust and dirt samples had greater concentrations associated with the higher-chlorinated homologue groups. PCB-congeners 153, 138, 101, 118, and 180 contributed >50% of the total PCBs mass in each sample, suggesting contamination with Aroclors 1254 and 1260. Total PCB concentrations for the dust and dirt samples ranged between 90 and 1700 ng g-1. Samples with the highest concentrations were located across the street and downwind from an industrial lot that had been remediated for PCB contamination in 1988. The industrial lot had been contaminated with Aroclors 1254 and 1260, indicating that contaminated soil had been locally redistributed through natural and vehicle-generated wind. Calculations based on the particle size of the street dust confirm the possibility of wind-induced redistribution. Street and aggregate lot dust and dirt potentially contribute to Buffalo River PCBs loadings through combined sewer overflows and stormwater runoff. Best management practices such as more frequent street sweeping may be useful in reducing these loadings.

Distribution of selected PCB congeners in the Babcock Street sewer district: a multimedia approach to identify PCB sources in combined sewer overflows (CSOs) discharging to the Buffalo River, New York.

To evaluate sources of PCBs in combined sewer overflows (CSOs) to the Buffalo River, New York, combined sewage, sanitary flow, atmospheric wet and dry depositions, and street dust samples were collected from the Babcock Street sewer district and analyzed. Total PCB concentrations (sum of the PCB congeners quantitated) in particulate and dissolved phases of sanitary flow were 101-269 ng g-1 dry weight and <0.2 ng L-1, respectively. PCBs in the atmospheric dry and wet deposition samples were close to the method detection limit (a few pg/cm2 day-1 and <0.2 ng L-1, respectively). Average concentrations of total PCBs were noticeable in both dissolved (64 ng/l-1) and particulate (907 ng g-1 dry weight) phases in CSOs. Total PCBs in aggregates of street dust samples were between 53 and 1,700 ng g-1 dry weight, with the highest concentrations at sites nearest an industrial area that was previously remediated for PCB contamination. PCB congeners 153, 138, 101, 118, and 180 contributed >50% of the total PCB load in street dust samples. PCB congener composition in the particulate phase of CSOs reflects the congener pattern of the street dusts. In this context, it can be suggested that the local contaminated street dusts are one of the potential sources of PCBs in CSOs, which is a source of PCBs to the Buffalo River.

Effects of PCB contamination on the reproduction of the DAB Limanda limanda L. under laboratory conditions

The effect of PCB contamination on the reproduction of female dab was studied under laboratory conditions. Females were contaminated during gonad maturation by multiple oral administration of capsules containing the technical PCB mixture Clophen A40. PCB contamination resulted in increased levels in the eggs, with concentrations of selected PCB congeners of 35 to 86 μg·g −1 lipid for PCB-exposed fish, 10 μg·g −1 lipid for eggs from fish fed with mussel meat and fish fed with shrimp. A statistically significant dose-effect relationship was found between the PCB content of the eggs and the PCB dose ingested by the fish. For eggs from the PCB-treated fish the mean fertilization rate was 61% and mean hatching 45%, compared to 67% fertilization and 59% hatching for eggs from untreated fish. Rate of development and survival of the eggs and mortality of the larvae after hatching were mainly related to incubation temperature. No statistically significant differences between untreated and PCB-treated fish could be found in egg production, egg quality, fertilization rate, hatching rate and survival of larvae.

The Distribution of 42 PCBs, Including Three Coplanar Congeners, in the Food Web of the Western Basin of Lake Erie

Non-ortho substituted PCBs, IUPAC numbers 77, 126, and 169, along with 39 other PCB congeners were quantified in samples of Lake Erie sediment and biota during the summer of 1991. Many PCB congeners were found at elevated levels, and biomagnification was apparent in all congeners but was more predominant in congeners with relatively high octanol-water partition coefficients (log K ow > 6.0). PCA analysis suggested that most PCB congeners had similar distributions in the Lake Erie food web, although congeners with very high Kows and coplanar congeners IUPAC # 77, 126, and 169 were found to have different distributions. Non-parametric statistics were used to determine if significant differences in concentration of selected PCB congeners existed among species and among tissues. Congener 126 was found primarily in benthic fish and top predators, whereas there was no significant differences in the concentrations of congener 77 in fish species of the benthic and pelagic food web. Congener 169 was found at very low concentrations in the food web of Lake Erie. There were also significant differences in concentrations of coplanar PCBs among liver, egg, and muscle tissues, but trends were not consistent among all the species examined. As significant differences were observed in the distribution of PCB congeners in the Lake Erie food web “total PCB” might not be an adequate estimation of the toxicological hazards associated with PCB accumulation. It is evident that the dynamics of individual congeners, in particular the coplanar PCBs, need to be accurately assessed in order to predict the environmental hazard of PCBs.

Polychlorinated biphenyls and organochlorine pesticides in marine sediments and seawater along the coast of Alicante, Spain

In this paper we present the results obtained in a sampling programme carried out from 1989–1990, whose aim was to study the presence of organochlorine compounds in marine sediments and seawater along the coast of Alicante, Spain. There have been identified DDTs, HCHs, HCB, cyclodienic pesticides and derivatives and PCBs (Aroclor type commercial mixtures and selected PCB congeners). The analytical method consists of 3 phases, i.e. extraction, cleanup and analysis through capillary gas chromatography with electron capture detection. The amount of material used for extraction was 1 kg of sediment samples and 50 l of seawater samples. The levels of organochlorines in sediments are low. Concentration ranges were as follows: PCB total, 0.05–9.69 ng g −1, sum of DDTs, 0.01–0.3 ng g −1, Hexachlorobenzene (HCB), 0.01–0.12 ng g −1, and smaller values for other compounds. In the dissolved phase of seawater there were identified HCHs in concentrations ranging from 1.3–2 ng l −1.

Acute toxicity of PCB congeners toDaphnia magna andPimephales promelas

The acute toxicity (EC50/LC50) of commercial PCB mixtures has been reported to range from 2.0 to 283 ug/L. Because PCBs are very hydrophobic most biological studies have utilized a carrier solvent to facilitate introduction of PCBs into aqueous solution. As a result, biological effects are often reported at exposure concentrations exceeding water solubility. The purpose of this work was to evaluate the comparative toxicity of selected PCB congeners without carrier solvents. These tests were conducted on early life stages of two sensitive freshwater organisms, Daphnia magna and Pimephales promelas.

Aqueous solubility and Henry's law constant data for PCB congeners for evaluation of quantitative structure-property relationships (QSPRs)

Aqueous solubilities and Henry's Law Constants (HLCs) were measured for selected PCB congeners for evaluation of quantitative structure-property relationships (QSPRs) relating chlorine substitution pattern to the chemical parameter. Experimental results were consistent with previously published values. Aqueous solubilities (as solids at 25°C, column generation technique) determined for 26 congeners ranged from 1.08×10 −5 to 9.69×10 −10 mol/L and generally decreased with molecular weight. Values converted to subcooled liquids are also reported. HLCs (25°C, gas purge technique) determined for 20 congeners ranged from 0.3×10 −4 to 8.97×10 −4 atm·m 3/mol. Measured HLCs were not correlated with molecular weight, but increased with degree of orthochlorine substitution within a molecular weight class. Vapor pressures calculated from the product of solubility (mol/m 3) and HLC (atm·m 3/mol) data, generally decreased with molecular weight and increased with increasing degree of ortho- chlorine substitution. Currently available QSPRs were found to be ineffective for predicting solubilities, HLCs and vapor pressures when compared to experimentally determined results. An empirical data fitting approach based on coefficients related to chlorine substitution patterns appears promising.

Reversed phase liquid chromatography of PCBs as a basis for the calculation of water solubility and log K ow for polychlorobiphenyls

Water solubility (Sw) and log Kow values have been determined for 154 possible polychlorobiphenyls using the retention indices obtained by RP-HPLC and structurally selected PCB congeners with known log Kow values for the regression lines. The water solubility data are melting point corrected.

The role of small, low density particles on the partition of selected PCB congeners between water and suspended matter (North Sea area)

The dissolved and particulate suspended concentrations of five PCB congeners (with 3–7 chlorine atoms) in the Southern Bight (North Sea) are interpreted in terms of an equilibrium partitioning model. K d values for riverine/coastal samples generally increase with chlorine number of the congeners (K d = 10 4–10 6). Values are more than an order of magnitude larger at the low suspended matter concentrations offshore (< 1 mg·dm −3). This is interpreted in terms of the presence of different SPM fractions with different contents of PCB: a fraction consisting of low size/density particles carrying high contents of PCBs, dominates at low SPM concentrations. The contribution of particulate forms to the total PCB concentration per unit volume may, therefore, be significant even at low SPM concentrations.