The Experts below are selected from a list of 7413 Experts worldwide ranked by ideXlab platform
Francesc Ventura - One of the best experts on this subject based on the ideXlab platform.
-
stir bar sorptive extraction thermal desorption gas chromatography mass spectrometry an effective tool for determining persistent organic pollutants and Nonylphenol in coastal waters in compliance with existing directives
Marine Pollution Bulletin, 2010Co-Authors: Juan Sanchezavila, Francesc Ventura, Jordi Quintana, Roma Tauler, Carlos M Duarte, Silvia LacorteAbstract:A multi-residual method based on stir bar sorptive extraction coupled with thermal desorption-gas chromatography-mass spectrometry (SBSE-TD-GC-MS) has been developed to measure 49 organic pollutants (organochlorine pesticides, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, polybrominated diphenyl ethers and Nonylphenol) in seawater. Using 100ml of water, the method exhibited good linearity, with recoveries between 86% and 118% and relative standard deviation between 2% and 24% for almost all compounds. The method was applied to determine target contaminants in Catalonian seawater, including coastal areas, ports and desalination plant feed water. Overall individual compound levels oscillated between 0.16 and 597 ng l(-1); PAHs and nonylpenol were the compounds found at the highest concentrations. The method provided LODs between 0.011 and 2.5 ng l(-1), lower than the Environmental Quality Standards (EQS) fixed by Directive 2008/105/EC. In compliance with the directive, this method can be used as a tool to survey target compounds and is aimed at protecting coastal ecosystems from chemical pollution.
-
estrogenic potential of halogenated derivatives of Nonylphenol ethoxylates and carboxylates
Environmental Toxicology and Chemistry, 2004Co-Authors: Natalia Garciareyero, Birgit Fischer, Mira Petrovic, Alfredo Diaz, Francesc Ventura, Damia Barcelo, Vanessa Requena, Peterdiedrich Hansen, Benjamin PinaAbstract:Halogenated derivatives of Nonylphenol and of its alkylates are generated during drinking water disinfection and treatment procedures. In this paper we analyze the potential of these compounds to interact with the estrogen receptor and to activate hormone-regulated gene promoters. We used the recombinant yeast assay (RYA) and the human breast cancer cell MCF7 proliferation assay for both estrogenic and antiestrogenic activities and the enzyme-linked receptor assay to examine in vitro binding to the receptor. Many Nonylphenol derivatives were very weak estrogens in our functional tests when compared to Nonylphenol while retaining a substantial affinity for the estrogen receptor in vitro. Antiestrogenicity tests demonstrated that brominated Nonylphenol and most of the carboxylated compounds studied here behaved as estrogenic antagonists in the RYA. We also detected an increased cytotoxicity for the carboxylated derivatives in both yeast and mammalian cells. We conclude that derivatization may mask the apparent estrogenicity of Nonylphenol, but the resulting compounds still represent a potential hazard since they are still able to bind the estrogen receptor and to influence the physiological response to estrogens. Our results also illustrate the advantage of combining different methods to assay estrogenicity of unknown substances.
-
low nanogram per liter determination of halogenated Nonylphenols Nonylphenol carboxylates and their non halogenated precursors in water and sludge by liquid chromatography electrospray tandem mass spectrometry
Journal of the American Society for Mass Spectrometry, 2003Co-Authors: Mira Petrovic, Alfredo Diaz, Damia Barcelo, Francesc VenturaAbstract:A new LC-MS-MS method for quantitative analysis of Nonylphenol (NP), Nonylphenol carboxylates (NPECs), and their halogenated derivatives: brominated and chlorinated Nonylphenols (BrNP, ClNP), brominated and chlorinated Nonylphenol carboxylates (BrNPE1C and ClNPE1C) and ethoxycarboxylates (BrNPE2C and ClNPE2C) in water and sludge has been developed. Electrospray negative ionization MS-MS was applied for the identification of above mentioned compounds. Upon collision-induced dissociation, their deprotonated molecules gave different fragments formed by the cleavage of the alkyl moiety and/or (ethoxy)carboxylic moiety. For halogenated compounds a highly diagnostic characteristic pattern of isotopic doublet signals was obtained and fragmentation yielded, in addition to above mentioned ions, [Br]− and [Cl]−, respectively. Quantitative analysis was done in the multiple reaction monitoring (MRM) mode, using two specific combinations of a precursor-product ion transitions for each compound. Additionally, for halogenated compounds two specific channels for each transition reaction, corresponding to two isotopes, were monitored and the ratio of their abundances used as an identification criterion. The method has been validated in terms of sensitivity, selectivity, accuracy, and precision and was applied to the analysis of water and sludge samples from drinking water treatment plant (DWTP) of Barcelona (Catalonia, NE Spain). Halogenated NP and NPECs were detected in prechlorinated water in concentrations up to 315 ng/L, BrNPE2C being the most abundant compound. In the DWTP effluent non-halogenated compounds were detected at trace levels (85, 12 and 10 ng/L for NP, NPE1C, and NPE2C, respectively), whereas concentration of halogenated derivatives never exceeded 10 ng/L. Nonylphenol, brominated and chlorinated NPs were found in flocculation sludge in concentrations of 150, 105, and 145 µg/kg, respectively. Acidic polar metabolites were found in lower concentrations up to 20 µg/kg.
-
simultaneous determination of halogenated derivatives of alkylphenol ethoxylates and their metabolites in sludges river sediments and surface drinking and wastewaters by liquid chromatography mass spectrometry
Analytical Chemistry, 2001Co-Authors: Mira Petrovic, Alfredo Diaz, Francesc Ventura, Damia BarceloAbstract:A quantitative solid-phase extraction-liquid chromatography/mass spectrometry (SPE-LC/MS) method is described for the simultaneous analysis of halogenated byproducts of alkylphenolic compounds and their degradation products formed during chlorine disinfection in the presence of bromide ions. Compounds analyzed include brominated and chlorinated Nonylphenol ethoxylates (XNPEOs); octylphenol ethoxylates (XOPEOs); Nonylphenols (XNP); nonylphenoxycarboxylates (XNPECs) and their precursors nonionic surfactants, alkylphenol ethoxylates (APEOs); and their metabolites formed during sewage treatment, alkylphenoxycarboxylates (APECs) and alkylphenols (APs). Target compounds were concentrated from water samples using a C18 SPE procedure. Extracts were analyzed using reversed phase LC/MS. The performances of both atmospheric pressure chemical ionization (APCI) and electrospray (ESI) interfaces were compared. ESI offered better sensitivity and specificity for a higher range of oligomers. Detection limits (LODs) for wa...
Klaus Guenther - One of the best experts on this subject based on the ideXlab platform.
-
Determination of Endocrine-Disrupting Nonylphenols and Nonylphenol Carboxylates by High-Performance Liquid Chromatography-Tandem Mass Spectrometry: Levels in German Food after Restriction
2021Co-Authors: Nasser Al Rashed, Klaus GuentherAbstract:Nonylphenols (NPs) and Nonylphenol carboxylates (NPECs) are products of the biodegradation of Nonylphenol ethoxylates (NPEOs), which is a widely used group of nonionic surfactants. These compounds are persistent, toxic, and exhibit estrogenic activity. Global scientific and public discourse has revealed the consequences of long-term dietary exposure to these endocrine disrupters. Since 2005, the utilization and sale of NPEOs and NPs have been regulated in some industrial applications by Directive 2003/53/EC of the European Union (EU). The objective of this investigation was to assess the NPs and NPECs concentration levels in foodstuffs following the implementation of the EU directive. Using a method based on high-performance liquid chromatography combined with tandem mass spectrometry (HPLC-MS), NPs and NPECs were determined in the same German food basket that was examined before the restriction. NPs were detected in 22 of the 24 food samples, whereas NPECs were below the limit of detection. The concentrations of NPs on a fresh weight basis varied between 0.1 and 6.3 μg kg−1. Based on the data of food consumption rates in Germany and the concentrations of NPs in the food samples, the daily NP intake for an adult was determined to be 2.7 µg day−1, which is one-third of the value found in the 2002 study. However, our findings revealed that NPs remain ubiquitous in foods at relevant concentrations, which highlights the need for further examinations in particular the isomer-specific aspects. This is especially important as Nonylphenol is found in human blood in many studies.
-
endocrine disrupting nonyl and octylphenol in infant food in germany considerable daily intake of Nonylphenol for babies
Chemosphere, 2011Co-Authors: Torsten Raecker, Bjoern Thiele, Roswitha M Boehme, Klaus GuentherAbstract:Abstract Nonylphenol and octylphenol are persistent endocrine disrupters that are priority substances of the European Union Water Framework Directive. Their presence in the environment has caused increasing concern about their impact to human health. Infants are more sensitive to hormonal impacts of environmental chemicals than adults. The results of the present study indicate that Nonylphenol is ubiquitous in foodstuffs for babies and toddlers commercially available in Germany, while octylphenol could only be determined in 80% of all food samples. The daily intakes based on consumption studies in μg Nonylphenol kg −1 body weight per day for high consumers in the baby category (0.23–0.65 μg kg −1 bw d −1 ) were relatively high. This could lead to a higher risk especially for babies.
-
a novel metabolic pathway for degradation of 4 Nonylphenol environmental contaminants by sphingomonas xenophaga bayram ipso hydroxylation and intramolecular rearrangement
Journal of Biological Chemistry, 2005Co-Authors: Frederic L P Gabriel, Walter Giger, Klaus Guenther, Andy Heidlberger, Daniel Rentsch, Hanspeter E KohlerAbstract:Several Nonylphenol isomers with alpha-quaternary carbon atoms serve as growth substrates for Sphingomonas xenophaga Bayram, whereas isomers containing hydrogen atoms at the alpha-carbon do not. Three metabolites of 4-(1-methyloctyl)-phenol were isolated in mg quantities from cultures of strain Bayram supplemented with the growth substrate isomer 4-(1-ethyl-1,4-dimethyl-pentyl)-phenol. They were unequivocally identified as 4-hydroxy-4-(1-methyl-octyl)-cyclohexa-2,5-dienone, 4-hydroxy-4-(1-methyl-octyl)-cyclohex-2-enone, and 2-(1-methyl-octyl)-benzene-1,4-diol by high pressure liquid chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy. Furthermore, two metabolites originating from 4-n-Nonylphenol were identified as 4-hydroxy-4-nonyl-cyclohexa-2,5-dienone and 4-hydroxy-4-nonyl-cyclohex-2-enone by high pressure liquid chromatography-mass spectrometry. We conclude that Nonylphenols were initially hydroxylated at the ipso-position forming 4-alkyl-4-hydroxy-cyclohexa-2,5-dienones. Dienones originating from growth substrate Nonylphenol isomers underwent a rearrangement that involved a 1,2-C,O shift of the alkyl moiety as a cation to the oxygen atom of the geminal hydroxy group yielding 4-alkoxyphenols, from which the alkyl moieties can be easily detached as alcohols by known mechanisms. Dienones originating from nongrowth substrates did not undergo such a rearrangement because the missing alkyl substituents at the alpha-carbon atom prevented stabilization of the putative alpha-carbocation. Instead they accumulated and subsequently underwent side reactions, such as 1,2-C,C shifts and dihydrogenations. The ipso-hydroxylation and the proposed 1,2-C,O shift constitute key steps in a novel pathway that enables bacteria to detach alpha-branched alkyl moieties of alkylphenols for utilization of the aromatic part as a carbon and energy source.
-
differential degradation of Nonylphenol isomers by sphingomonas xenophaga bayram
Applied and Environmental Microbiology, 2005Co-Authors: Frederic L P Gabriel, Walter Giger, Klaus Guenther, Hanspeter E KohlerAbstract:Sphingomonas xenophaga Bayram, isolated from the activated sludge of a municipal wastewater treatment plant, was able to utilize 4-(1-ethyl-1,4-dimethylpentyl)phenol, one of the main isomers of technical Nonylphenol mixtures, as a sole carbon and energy source. The isolate degraded 1 mg of 4-(1-ethyl-1,4-dimethylpentyl)phenol/ml in minimal medium within 1 week. Growth experiments with five Nonylphenol isomers showed that the three isomers with quaternary benzylic carbon atoms [(1,1,2,4-tetramethylpentyl)phenol, 4-(1-ethyl-1,4-dimethylpentyl)phenol, and 4-(1,1-dimethylheptyl)phenol] served as growth substrates, whereas the isomers containing one or two hydrogen atoms in the benzylic position [4-(1-methyloctyl)phenol and 4-n-Nonylphenol] did not. However, when the isomers were incubated as a mixture, all were degraded to a certain degree. Differential degradation was clearly evident, as isomers with more highly branched alkyl side chains were degraded much faster than the others. Furthermore, the C9 alcohols 2,3,5-trimethylhexan-2-ol, 3,6-dimethylheptan-3-ol, and 2-methyloctan-2-ol, derived from the three Nonylphenol isomers with quaternary benzylic carbon atoms, were detected in the culture fluid by gas chromatography-mass spectrometry, but no analogous metabolites could be found originating from 4-(1-methyloctyl)phenol and 4-n-Nonylphenol. We propose that 4-(1-methyloctyl)phenol and 4-n-Nonylphenol were cometabolically transformed in the growth experiments with the mixture but that, unlike the other isomers, they did not participate in the reactions leading to the detachment of the alkyl moiety. This hypothesis was corroborated by the observed accumulation in the culture fluid of an as yet unidentified metabolite derived from 4-(1-methyloctyl)phenol.
Damia Barcelo - One of the best experts on this subject based on the ideXlab platform.
-
estrogenic potential of halogenated derivatives of Nonylphenol ethoxylates and carboxylates
Environmental Toxicology and Chemistry, 2004Co-Authors: Natalia Garciareyero, Birgit Fischer, Mira Petrovic, Alfredo Diaz, Francesc Ventura, Damia Barcelo, Vanessa Requena, Peterdiedrich Hansen, Benjamin PinaAbstract:Halogenated derivatives of Nonylphenol and of its alkylates are generated during drinking water disinfection and treatment procedures. In this paper we analyze the potential of these compounds to interact with the estrogen receptor and to activate hormone-regulated gene promoters. We used the recombinant yeast assay (RYA) and the human breast cancer cell MCF7 proliferation assay for both estrogenic and antiestrogenic activities and the enzyme-linked receptor assay to examine in vitro binding to the receptor. Many Nonylphenol derivatives were very weak estrogens in our functional tests when compared to Nonylphenol while retaining a substantial affinity for the estrogen receptor in vitro. Antiestrogenicity tests demonstrated that brominated Nonylphenol and most of the carboxylated compounds studied here behaved as estrogenic antagonists in the RYA. We also detected an increased cytotoxicity for the carboxylated derivatives in both yeast and mammalian cells. We conclude that derivatization may mask the apparent estrogenicity of Nonylphenol, but the resulting compounds still represent a potential hazard since they are still able to bind the estrogen receptor and to influence the physiological response to estrogens. Our results also illustrate the advantage of combining different methods to assay estrogenicity of unknown substances.
-
low nanogram per liter determination of halogenated Nonylphenols Nonylphenol carboxylates and their non halogenated precursors in water and sludge by liquid chromatography electrospray tandem mass spectrometry
Journal of the American Society for Mass Spectrometry, 2003Co-Authors: Mira Petrovic, Alfredo Diaz, Damia Barcelo, Francesc VenturaAbstract:A new LC-MS-MS method for quantitative analysis of Nonylphenol (NP), Nonylphenol carboxylates (NPECs), and their halogenated derivatives: brominated and chlorinated Nonylphenols (BrNP, ClNP), brominated and chlorinated Nonylphenol carboxylates (BrNPE1C and ClNPE1C) and ethoxycarboxylates (BrNPE2C and ClNPE2C) in water and sludge has been developed. Electrospray negative ionization MS-MS was applied for the identification of above mentioned compounds. Upon collision-induced dissociation, their deprotonated molecules gave different fragments formed by the cleavage of the alkyl moiety and/or (ethoxy)carboxylic moiety. For halogenated compounds a highly diagnostic characteristic pattern of isotopic doublet signals was obtained and fragmentation yielded, in addition to above mentioned ions, [Br]− and [Cl]−, respectively. Quantitative analysis was done in the multiple reaction monitoring (MRM) mode, using two specific combinations of a precursor-product ion transitions for each compound. Additionally, for halogenated compounds two specific channels for each transition reaction, corresponding to two isotopes, were monitored and the ratio of their abundances used as an identification criterion. The method has been validated in terms of sensitivity, selectivity, accuracy, and precision and was applied to the analysis of water and sludge samples from drinking water treatment plant (DWTP) of Barcelona (Catalonia, NE Spain). Halogenated NP and NPECs were detected in prechlorinated water in concentrations up to 315 ng/L, BrNPE2C being the most abundant compound. In the DWTP effluent non-halogenated compounds were detected at trace levels (85, 12 and 10 ng/L for NP, NPE1C, and NPE2C, respectively), whereas concentration of halogenated derivatives never exceeded 10 ng/L. Nonylphenol, brominated and chlorinated NPs were found in flocculation sludge in concentrations of 150, 105, and 145 µg/kg, respectively. Acidic polar metabolites were found in lower concentrations up to 20 µg/kg.
-
simultaneous determination of halogenated derivatives of alkylphenol ethoxylates and their metabolites in sludges river sediments and surface drinking and wastewaters by liquid chromatography mass spectrometry
Analytical Chemistry, 2001Co-Authors: Mira Petrovic, Alfredo Diaz, Francesc Ventura, Damia BarceloAbstract:A quantitative solid-phase extraction-liquid chromatography/mass spectrometry (SPE-LC/MS) method is described for the simultaneous analysis of halogenated byproducts of alkylphenolic compounds and their degradation products formed during chlorine disinfection in the presence of bromide ions. Compounds analyzed include brominated and chlorinated Nonylphenol ethoxylates (XNPEOs); octylphenol ethoxylates (XOPEOs); Nonylphenols (XNP); nonylphenoxycarboxylates (XNPECs) and their precursors nonionic surfactants, alkylphenol ethoxylates (APEOs); and their metabolites formed during sewage treatment, alkylphenoxycarboxylates (APECs) and alkylphenols (APs). Target compounds were concentrated from water samples using a C18 SPE procedure. Extracts were analyzed using reversed phase LC/MS. The performances of both atmospheric pressure chemical ionization (APCI) and electrospray (ESI) interfaces were compared. ESI offered better sensitivity and specificity for a higher range of oligomers. Detection limits (LODs) for wa...
Alaa El-din H. Sayed - One of the best experts on this subject based on the ideXlab platform.
-
Protective effect of Nigella sativa on 4-Nonylphenol-induced nephrotoxicity in Clarias gariepinus (Burchell, 1822)
The Science of the total environment, 2017Co-Authors: Ahmed Kotb, Mahmoud Abd-elkareem, Nasser S. Abou Khalil, Alaa El-din H. SayedAbstract:Abstract The aim of this study was to examine the protective effects of Nigella sativa ( N. sativa ) on 4-Nonylphenol-induced nephrotoxicity in Clarias gariepinus . 30 fishes were divided into five groups: control, 4-Nonylphenol-treated, 1% N. sativa treated, 2.5% N. sativa treated, and 5% N. sativa treated. N. sativa and 4-Nonylphenol were given for 3 weeks. 4-NP and 4-NP- N. sativa treated fishes were compared with the control group. Kidney histology, immunochemistry, and electron microscope were assessed after 4-NP exposure. In the African catfish, 4-NP is mainly excreted through the kidney causing nephrotoxicity. Our results showed that 4-NP administration significantly disturbed the kidney structure and function. 4-NP treated fishes showed dilated glomerular vessels, fewer glomerular cells content, decreased expressions of glomerular proteins, and increased level of autophagy compared to control group ( P N. sativa has different immunological and pharmacological effects such as anti-apoptotic and anti-oxidant, therefore, the administration of N. sativa with 4-Nonylphenol significantly minimize the nephrotoxic effect of 4-NP and maintain the normal kidney structure and function. Our novel study demonstrated for the first time that N. sativa could protect the kidney against 4-NP induced-nephrotoxicity.
-
antioxidant and antiapoptotic activities of calotropis procera latex on catfish clarias gariepinus exposed to toxic 4 Nonylphenol
Ecotoxicology and Environmental Safety, 2016Co-Authors: Alaa El-din H. Sayed, Nadia H. Mohamed, M. A. Ismail, Wael M Abdelmageed, Ahmed Am ShoreitAbstract:Calotropis procera L. is known as medicinal plant. The Phytochemical analyzes of its latex revealed that it possessed antioxidants, namely terpenes, phenolic compounds and cardenolides, flavonoids and saponins, while tannins, alkaloids and resin were absent in moderate to high concentration. In the present study, the role of latex of Calotropis procera as antioxidant and antiapoptotic was reported. To carry out this aim, fishes were exposed to 100 µg l(-1) 4-Nonylphenol as chemical pollutant. The enzymes, superoxidase dismutase, catalase, acetlycholinstrase (AchE), glutathione s-transferase, cortisol, G6PDH) and apoptotic cells increased significantly (p<0.05) accompanied by irregular disturbance of (Na(+), K(+)) ions in the presence of 4-Nonylphenol. On the other hand, these enzymes, ions, and apoptotic cells decreased normally and significantly (p<0.05) in the presence of latex. Total phenol content, total capacity antioxidant, reducing power decrease significantly (p<0.05) in the presence of 4-Nonylphenol and increase normally in the presence of latex. Latex was used for the first time to protect catfish after 4-Nonylphenol exposure. Our study confirms that crude latex of Calotropis procera possessed antioxidant and antiapoptotic activities against the toxicity of 4-Nonylphenol.
-
Effects of 4-Nonylphenol on blood cells of the African catfish Clarias gariepinus (Burchell, 1822).
Tissue & cell, 2011Co-Authors: A.a. Mekkawy, Usama M. Mahmoud, Alaa El-din H. SayedAbstract:In the present work, the destructive effects of the 4-Nonylphenol on one of the most economically important Nile fishes, namely African catfish (Clarias gariepinus) were studied. Apoptosis, erythrocytes alterations, micronucleus test and blood parameters count were used as biological indicators to detect those effects. After exposure to sublethal concentrations of 4-Nonylphenol (0, 0.05, 0.08 and 0.1mg/l), apoptotic red blood cells with many malformations and micronucleated erythrocytes were recorded. Decrease in the blood parameters such as red blood cells (RBCs), hemoglobin (Hb), package cell volume (PCV), mean corpuscular hemoglobin concentration (MCHC), platelets, white blood cells (WBCs), lymphocytes, basophils, monocytes and increase in mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), neutrophils, eosinophils indicated the negative effects of 4-Nonylphenol. It was concluded that, the 4-Nonylphenol caused genotoxicity in erythrocytes with many malformations in shape and number indicated with other blood parameters.
Walter Giger - One of the best experts on this subject based on the ideXlab platform.
-
a novel metabolic pathway for degradation of 4 Nonylphenol environmental contaminants by sphingomonas xenophaga bayram ipso hydroxylation and intramolecular rearrangement
Journal of Biological Chemistry, 2005Co-Authors: Frederic L P Gabriel, Walter Giger, Klaus Guenther, Andy Heidlberger, Daniel Rentsch, Hanspeter E KohlerAbstract:Several Nonylphenol isomers with alpha-quaternary carbon atoms serve as growth substrates for Sphingomonas xenophaga Bayram, whereas isomers containing hydrogen atoms at the alpha-carbon do not. Three metabolites of 4-(1-methyloctyl)-phenol were isolated in mg quantities from cultures of strain Bayram supplemented with the growth substrate isomer 4-(1-ethyl-1,4-dimethyl-pentyl)-phenol. They were unequivocally identified as 4-hydroxy-4-(1-methyl-octyl)-cyclohexa-2,5-dienone, 4-hydroxy-4-(1-methyl-octyl)-cyclohex-2-enone, and 2-(1-methyl-octyl)-benzene-1,4-diol by high pressure liquid chromatography-mass spectrometry and nuclear magnetic resonance spectroscopy. Furthermore, two metabolites originating from 4-n-Nonylphenol were identified as 4-hydroxy-4-nonyl-cyclohexa-2,5-dienone and 4-hydroxy-4-nonyl-cyclohex-2-enone by high pressure liquid chromatography-mass spectrometry. We conclude that Nonylphenols were initially hydroxylated at the ipso-position forming 4-alkyl-4-hydroxy-cyclohexa-2,5-dienones. Dienones originating from growth substrate Nonylphenol isomers underwent a rearrangement that involved a 1,2-C,O shift of the alkyl moiety as a cation to the oxygen atom of the geminal hydroxy group yielding 4-alkoxyphenols, from which the alkyl moieties can be easily detached as alcohols by known mechanisms. Dienones originating from nongrowth substrates did not undergo such a rearrangement because the missing alkyl substituents at the alpha-carbon atom prevented stabilization of the putative alpha-carbocation. Instead they accumulated and subsequently underwent side reactions, such as 1,2-C,C shifts and dihydrogenations. The ipso-hydroxylation and the proposed 1,2-C,O shift constitute key steps in a novel pathway that enables bacteria to detach alpha-branched alkyl moieties of alkylphenols for utilization of the aromatic part as a carbon and energy source.
-
differential degradation of Nonylphenol isomers by sphingomonas xenophaga bayram
Applied and Environmental Microbiology, 2005Co-Authors: Frederic L P Gabriel, Walter Giger, Klaus Guenther, Hanspeter E KohlerAbstract:Sphingomonas xenophaga Bayram, isolated from the activated sludge of a municipal wastewater treatment plant, was able to utilize 4-(1-ethyl-1,4-dimethylpentyl)phenol, one of the main isomers of technical Nonylphenol mixtures, as a sole carbon and energy source. The isolate degraded 1 mg of 4-(1-ethyl-1,4-dimethylpentyl)phenol/ml in minimal medium within 1 week. Growth experiments with five Nonylphenol isomers showed that the three isomers with quaternary benzylic carbon atoms [(1,1,2,4-tetramethylpentyl)phenol, 4-(1-ethyl-1,4-dimethylpentyl)phenol, and 4-(1,1-dimethylheptyl)phenol] served as growth substrates, whereas the isomers containing one or two hydrogen atoms in the benzylic position [4-(1-methyloctyl)phenol and 4-n-Nonylphenol] did not. However, when the isomers were incubated as a mixture, all were degraded to a certain degree. Differential degradation was clearly evident, as isomers with more highly branched alkyl side chains were degraded much faster than the others. Furthermore, the C9 alcohols 2,3,5-trimethylhexan-2-ol, 3,6-dimethylheptan-3-ol, and 2-methyloctan-2-ol, derived from the three Nonylphenol isomers with quaternary benzylic carbon atoms, were detected in the culture fluid by gas chromatography-mass spectrometry, but no analogous metabolites could be found originating from 4-(1-methyloctyl)phenol and 4-n-Nonylphenol. We propose that 4-(1-methyloctyl)phenol and 4-n-Nonylphenol were cometabolically transformed in the growth experiments with the mixture but that, unlike the other isomers, they did not participate in the reactions leading to the detachment of the alkyl moiety. This hypothesis was corroborated by the observed accumulation in the culture fluid of an as yet unidentified metabolite derived from 4-(1-methyloctyl)phenol.
-
estrogenic metabolites of alkylphenol polyethoxylates in secondary sewage effluents and rivers
Water Science and Technology, 2000Co-Authors: Marijan Ahel, Eva Molnar, S Ibric, Walter GigerAbstract:Degradation products of nonionic surfactants of the Nonylphenol polyethoxylate type (NPnEO) were reported recently to be estrogenic to fish at low microgram per litre concentrations. These estrogenic metabolites, including Nonylphenol (NP), Nonylphenol monoethoxylate (NP1EO) and Nonylphenol diethoxylate (NP2EO) as well as their corresponding carboxylic acids (NP1EC and NP2EC), were measured during 1997 and 1998 in sewage effluents and ambient waters in Switzerland in order to assess the effects of risk reduction measures introduced in 1986. Lipophilic metabolites (NP+NP1EO+NP2EO) were found in the examined secondary sewage effluents mostly at concentrations from 1 to 5 μg/L, while elevated levels were found in those sewage treatment plants which receive industrial effluents from textile finishing plants. The concentrations of the lipophilic Nonylphenolic compounds in rivers ranged mainly from 0.05 to 0.3 μg/L with NP being most abundant. The total concentration of the nonylphenoxy carboxylic acids was significantly higher than that of the lipophilic metabolites. Despite a significant decrease of the environmental exposure levels of all Nonylphenolic compounds subsequent to the introduction of risk reduction measures, the total concentration of estrogenic metabolites often exceeded the predicted no effect concentration (PNEC) of 0.33 μg/L proposed in a risk assessment report to the European Union.
-
behaviour of alkylphenol polyethoxylate surfactants in the aquatic environment iii occurrence and elimination of their persistent metabolites during infiltration of river water to groundwater
Water Research, 1996Co-Authors: Marijan Ahel, Christian Schaffner, Walter GigerAbstract:Abstract The behaviour of various persistent metabolites derived from Nonylphenol polyethoxylate (NPnEO) surfactants was studied during infiltration of river water to groundwater at two field sites situated in the northern part of Switzerland (Glatt River and Sitter River). Nonylphenol (NP), Nonylphenol monoethoxylate (NP1EO), Nonylphenol diethoxylate (NP2EO), nonylphenoxy acetic acid (NP1EC) and nonylphenoxy(ethoxy) acetic acid (NP2EC) were observed in the two investigated rivers at relatively high concentrations with average values of the individual types of Nonylphenolic compounds ranging from 1.8 to 25 μg/l. The average concentrations of NP, NP1EO and NP2EO in groundwater were significantly lower (range NP1EO > NP > PCP > NP1EC = NP2EC.
-
behaviour of alkylphenol polyethoxylate surfactants in the aquatic environment i occurrence and transformation in sewage treatment
Water Research, 1994Co-Authors: Marijan Ahel, Walter Giger, Markus KochAbstract:Abstract Specific analytical techniques were used to study the behaviour of alkylphenol polyethoxylate surfactants (APnEO) in several full-scale mechanical-biological sewage treatment plants in the Glatt Valley, Switzerland. Both parent compounds and the major metabolic products were quantified. Untreated sewage and primary effluents contained considerable amounts of surfactant-derived Nonylphenolic compounds (3.0–9.6% of the dissolved organic carbon). Parent Nonylphenol polyethoxylates (nEO = 3–20) were efficiently eliminated during biological treatment. However, the overall rate of biodegradation was limited due to the formation of biorefractory metabolites, including Nonylphenol (NP), Nonylphenol mono- and diethoxylate (NP1EO, NP2EO) and nonylphenoxy carboxylic acids (NPEC). The abundance of a particular metabolite was very dependent on the treatment conditions. Studies of the mass flows of Nonylphenolic compounds in sewage treatment plants indicated that their fate was determined not only by microbial transformation, but also by physicochemical processes.
