To study the potential effects of the relative hydrophilic nitrogen containing polycyclic aromatic hydrocarbons (NPAH) in the aquatic environment, zebra mussels (Dreissena polymorpha) were exposed to the model compound acridine (benzo[b]quinoline). In a short-term experiment, the filtration rate of the mussels (1.5–2.0 cm) was measured after 48 h of exposure to different acridine concentrations in the water. In a chronic experiment (10 weeks), filtration rate was measured after 48 h and subsequently once a week, while mortality was monitored daily. Every other day, water and toxicant were renewed and mussels were fed algae (Scenedesmus acuminatus; 20 000 cells ml−1). Filtration rates were calculated from the decrease in algal concentration. After 48 h of exposure, a clear dose-response relationship was observed for filtration rate, from which the concentration reducing filtration to 50% of that of the controls (EC50) was calculated to be 0.96 mg acridine 1−1. During chronic exposure, adverse effects on filtration rate were comparable to those after 48 h, but at the highest acridine concentrations tested, mortality increased rapidly. However, after 4 weeks mortality ceased, coinciding with the disappearance of acridine from the water, in spite of the 48 h water and toxicant renewal. Meanwhile, a metabolite appeared on the HPLC chromatograms, identified as 9(10H)-acridone. The metabolism of acridine seems to have been induced or enhanced, leading to lower toxicant concentrations and diminishing effects on the mussels. There were indications that the mussels, periphyton and bacteria (growing on the walls of the aquaria and on the mussels) all contributed to the breakdown of acridine. Information on transformation of NPAHs in aquatic communities and on the toxicity of metabolites is essential for assessing the ecological risk of these compounds.

A microsomal assay with the enzyme cytochrome P450 offers a good experimental model to study the principles of the metabolism of polychlorinated dibenzofurans, -dibenzo-p-dioxins and -biphenyls (PCDFs, PCDDs, PCBs). To study the phenolic metabolites on a gas chromatograph with mass spectrometric or electron-capture detection, some clean-up is necessary to remove coextracted phospholipids and other interferences. In this study, two solid-phase clean-up columns were studied: Florisil and alumina B, as well as a destructive column: an acidic:basic impregnated silica column (ABSC). The elution profile and recovery of a methoxytetrachlorodibenzofuran (methoxy-TCDF) and a dimethoxytetrachlorobiphenyl (dimethoxy-TCB) were determined using pentane or dichloromethane as eluent. For comparison, a TCB and a TCDD were assessed as well. Both Florisil and alumina B yielded satisfactory results for all compounds. The ABSC showed low recoveries for the dimethoxy-TCB. Next both solid-phases were applied on the extract from microsomal assays with PCDFs and PCDDs. A successive combination of Florisil and alumina B resulted in samples sufficiently purified to allow for low concentration analysis. In addition attention was focused on several derivatisation methods. Methylation with methyl iodide and diazomethane and acetylation in an aqueous phase and an organic phase were studied. For the purpose of the present study the method with methyl iodide suited best.

Effects of four benzoquinoline isomers on the filtration rate of the zebra mussel ( Dreissena polymorpha ) were analyzed, to study the effect of minor differences in chemical structure on adverse biological effects. Filtration rates were measured after 48 h of exposure to different concentrations of acridine, phenanthridine, benzo[ f ]quinoline, and benzo[ h ]quinoline in the water. The 50% effective concentration (EC50) values for filtration rate of the four isomers differed significantly. Effects increased in the order benzo[ f ], ‐[ h ], ‐[ b ], and ‐[ c ]quinoline, and the difference between the most toxic isomer and the least toxic isomer amounted to a factor of 30. Attempts were made to relate these differences in toxicity to the structure of the isomers. Size‐ or topology‐related molecular descriptors provided insufficient resolution to distinguish between the benzoquinoline isomers, and none of the electronic descriptors separately provided a significant correlation with the observed effects. In an alternative approach, molecular shape, accessibility, and minimum agent–macromolecule distance were used to represent repulsive and attractive forces between the benzoquinoline isomers and biological membranes. This approach could tentatively explain the observed effects and is supported by a high correlation between the EC50 data and the reversed‐phase C18‐HPLC behavior of the benzoquinolines ( k 0 ), which is likely to be governed by similar processes.

Semi-empirical molecular modelling calculations of ring rotational energy barriers were carried out for 96 tetrachlorobenzyltoluenes (TCBTs) to provide insight in the possible coplanarity of these compounds, which is required for dioxin-type toxicity. Comparative calculations were performed for the structurally related polychlorinated biphenyls (PCBs) and polychlorinated diphenylethers (PCDEs). On account of this comparison PCBs, PCDEs and TCBTs were divided into groups of different energy barriers. PCDEs and TCBTs were classified into the same relatively high energy barrier groups. Using the criterion of fitting within a 3 * 10 Angstrom geometry and using structure activity relationships, our results indicate that two out of the 91 coplanar TCBTs can interact with the dioxin (Ah) receptor.

The metabolism of polychlorinated biphenyls, dibenzo-p-dioxins and dibenzofurans (PCBs, PCDDs, PCDFs) can be studied well with a cytochrome P450 containing microsomal assay. In the present study, the residues of microsomal assays were extracted with organic solvents to determine the metabolites of the studied compounds with GC-ECD and GC-MS. Extracts of microsomal assays contained a matrix which interferes with these type of measurements. The matrix was hard to remove completely with solid phase adsorption chromatography. To overcome the problem of the interfering compounds, clean-up properties of a gel permeation chromatography system were studied for this specific matrix. The clean-up was firstly studied with model compounds and two different mobile phases. Thereupon the most appropriate mobile phase was applied to the extracts of a microsomal assay. Acetone and cyclohexane-dichloromethane (CH-DCM, 1:1, v/v) were compared as mobile phases. The elution profiles of several lipids and some organohalogen compounds (OHCs) were determined. The mixture CH-DCM yielded the best separation between lipids and the OHCs. The results were discussed with a theoretical evaluation on the basis of interactions between solute, solvent and stationary phase. Recoveries were assessed for the GPC procedure and appeared to be good (98–100% for the column itselt and 80–100% for the sample transfer from vial to column). The GPC was integrated in the clean-up of the extract of a microsomal PCDF metabolism assay yielding satisfactory results.

The toxicity of three two-ring and five three-ring azaarenes to the green alga Scenedesmus acuminatus and its relationship with molecular structure was investigated.Indole, quinoline, isoquinoline, and carbazole did not inhibit the growth rate of S. acuminatus in 96-h batch culture assays up to 10 mg/L.Chlorophyll-a content appeared to be a more sensitive response parameter than growth for five of six compounds.This parameter showed a relationship with hydrophobicity-related molecular descriptors like molecular surface area.Four benzoquinoline isomers showed notably different effects on growth rate and chlorophyll-a content.Median effect concentration (EC50) values obtained for growth rate were acridine, 0.32 mg/L; benzo[f]quinoline, 1.55 mg/L; phenanthridine, 5.24 mg/L; and benzo[h]quinoline, 6.65 mg/L.Similar differences existed in their EC50 values for chlorophyll-a content.The differences in toxicity between these isomers correlates with two electronical molecular descriptors, viz. the ionization potential and the homo-lumo gap.Several modes of action are put forward and their relative importance discussed.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTFishing for quality in environmental analysis. Interlaboratory study on non- and mono-ortho chlorinated biphenylsPim de Voogt, Peter Haglund, Lars B. Reutergaardh, Cynthia de Wit, and Fredrik WaernCite this: Anal. Chem. 1994, 66, 5, 305A–311APublication Date (Print):March 1, 1994Publication History Published online22 September 2008Published inissue 1 March 1994https://pubs.acs.org/doi/10.1021/ac00077a002https://doi.org/10.1021/ac00077a002research-articleACS PublicationsRequest reuse permissionsArticle Views51Altmetric-Citations17LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts