A method to separate polychlorinated biphenyls (PCBs) by using high-performance liquid chromatography (HPLC) was developed. The HPLC column was packed with Amoco PX-21 activated carbon dispersed on octadecylsilane (ODS). The separation was carried out by gradient elution with n-hexane–dichloromethane and toluene in the forward direction followed by reversed elution with toluene. The results show that this HPLC method is useful for the separation of PCBs according to the number of substituted ortho chlorine atoms attached to the biphenyl structure. Average recoveries for a number of individual di-ortho PCBs, mono-ortho PCBs, and non-ortho PCBs in three selected elution windows were 97, 92, and 96%, respectively. Clophen A50, a herring sample, and a cod liver oil sample were fractionated on the column and the analytical results are compared with data from the literature. The method presented here is useful for quantitative separations of mono-ortho PCBs as well as non-ortho PCBs which have been assigned toxic equivalency factors by the World Health Organisation.

The concentrations and fluxes of polychlorinated naphthalenes (PCNs) were measured in surface sediments, and settling particulate matter collected in sediment traps, at two coastal and two offshore sampling stations in the Gulf of Bothnia, northern Baltic Sea, Sweden. The PCN concentrations (of tetra- to hepta-chloro congeners) in the surface sediments ranged from 0.27 to 2.8 ng/g dry weight and were of the same order of magnitude as background concentrations reported previously in Europe. The PCN fluxes in the southern basin (0.93 and 0.86 mug/m(2)/year) of the Gulf of Bothnia were higher than those in the northern basin (0.58 and 0.49 mug/m(2)/year); they were also higher near the coast than in the open sea. These PCN fluxes are similar to the pre-industrial levels determined from lake sediments in northwest England. The PCN homologue distribution changed from a relatively even distribution in samples collected near the coast, to TeCNs dominating in the samples from the open sea. This indicates that higher chlorinated PCNs are deposited and retained in sediments to a higher degree near the coast. The total annual deposition of PCNs in sediments in the Gulf of Bothnia was estimated to be 91 kg/year. (C) 2003 Elsevier Ltd. All rights reserved.

The congener-specific analysis of polychlorinated biphenyls (PCBs) by HRGC/LRMS as part of a multi-residue method is described. The results displayed SDs, in general <30%, for replicate samples from the same sampling location. Results for 68 PCB congeners, resolved on a PTE-5 or DB-5 column, in benthic fauna (amphipods (Monoporeia affinis), isopods (Saduria entomon) and fourhorn sculpins (Oncocottus quadricornis)) and sediments are presented for three coastal locations in the Bothnian Sea and two in the Bothnian Bay. The benthic fauna is suitable for monitoring environmental contaminants since it is stationary and it provides the staple diet of many fish and other predators. Sediments also give the contaminant loads of particular matter. Total PCB levels in the Bothnian Sea increased from north to south for sediments (∼ 1600–8500 ng g−1 extractable organic material), amphipods (∼ 400–1000 ng g−1 lipids) and isopods (700–2400 ng g−1 lipids). The levels in the Bothnian Bay were higher than in the most northerly location in the Bothnian Sea for sediments, amphipods and isopods. The trend for the sculpin samples from the different locations was, however, not so evident. A chemometrical comparison of the distribution of the PCB congeners at the different sampling sites using principal component analysis (PCA), revealed that PCB congener patterns differ between the Bothnian Bay and the Bothnian Sea.

The ethoxyresorufin O-deethylase (EROD) induction of 20 polychlorinated dibenzofurans (PCDFs) was examined in the H4IIE rat hepatoma cell bioassay. The selection of the compounds tested was based on a multivariate chemical characterization laying the groundwork for covering the whole chemical series of PCDFs. The EROD induction potency was found to vary in ED50 values from 25 to 100,000,000 pg/mg, i.e., nearly seven orders of magnitude. The response of the bioassay was calibrated against the 2,3,7,8-tetrachlorodibenzo-p-dioxin, enabling the corresponding toxic equivalency factors (TEFs) to be calculated. In order to establish a quantitative structure-activity relationship (QSAR) for the TEF values, 37 physicochemical descriptor variables were used to chemically characterize the 87 tetra- to octachlorinated PCDFs. Using partial least-squares modeling on a training set of 10 congeners, a QSAR model with sound predictive power was obtained. The QSAR model was validated with a validation set of additional 10 congeners. The predicted TEFs indicate that a large number of congeners are potent EROD inducers.

A multivariate characterization of the 136 tetra- to octa-chloro-substituted dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) is reported. By principal component analysis (PCA) of a battery of physicochemical descriptors, an overview of similarities and differences between congener groups and substitution patterns is obtained. Available data for two biochemical end points, the induction of the enzymes aryl hydrocarbon hydroxylase (AHH) and ethoxy resorufin O-deethylase (EROD), were used to construct quantitative structure-activity relationships (QSARs) using partial least-squares projections with latent variables (PLS). By applying the principles of statistical experimental design to the orthogonal scores from the PCA, a set of PCDD and PCDF congeners is proposed for further biological and toxicological evaluations.

The UV spectra of all the 87 tetra- to octachlorinated dibenzofurans (PCDFs) have been examined. The UV spectra reveal similarities and differences between homologue groups and substitution patterns. Two characteristic absorption maxima are seen in the range of 270 – 350 nm. The first maximum is located in the 290 – 305 nm region and the second maximum in the 315 – 335 nm region. The molar extinction coefficients of the main band vary between 10 and 43 mM−1 cm−1. Bathochromic shifts of both bands were observed with increasing number of chlorine atoms attached to the dibenzofuran ring systems. The 2,3,7,8-substitution pattern exhibits a characteristic maximum at 305 – 309 nm. The UV-spectral properties are useful for identification of individual congeners in the structural analysis of the PCDFs. The data may also aid in the use as physicochemical parameters in modelling of structure-activity relationships.

The structural and physico-chemical variation among the PCDDs and PCDFs were studied with a multitude of descriptor variables using principal component analysis. The principal properties obtained in these analysis were used as design variables in a 2(4)-factorial design resulting in sets of representative structures. These well balanced training sets of congeners are proposed for use in further chemical and biological monitoring or to be used as structure indicator compounds in complex mixtures.