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PubMed2004

Removal of chlorophenols from groundwater by chitosan sorption.

The equilibrium and kinetics of chlorophenol (CP) sorption by chitosan, poly D-glucosamine, were studied under simulated groundwater conditions. Lower temperature, from 25 degrees C to 15 degrees C and then 5 degrees C, markedly decreased the adsorption rates by a factor of 30-53% and 7-22%. Comparison between two types of chitosan, flakes and highly swollen beads, demonstrated that the maximum pentachlorophenol (PCP) uptake capacities in Langmuir and Freundlich models depend on the specific surface area of the particle. Low temperature (5 degrees C) significantly increased the PCP uptake capacity in comparison to higher temperatures (15 degrees C and 25 degrees C). PCP uptake capacity was halved at pH levels higher than 6.5, and NaCl concentrations greater than 1% blocked PCP sorption almost completely. Of five kinds of chlorophenols, i.e. 2,4,6-trichlorophenol (2,4,6-TCP), 3,4-dichlorophenol (3,4-DCP), 2,3-dichlorophenol (2,3-DCP), 2,6-dichlorophenol (2,6-DCP), 3-monochlorophenol (3-MCP), TCP had the maximum sorption efficiency on flake-type chitosan, followed by DCPs, and finally MCP (the three kinds of DCP, with the same elemental compositions, achieved similar sorption performances).

Adsorption↗
PubMed2005

Sorption of phenols onto sandy aquifer material: the effect of dissolved organic matter (DOM).

The influence of dissolved organic matter (DOM) on the sorption of four phenols, 2,4,6-trichlorophenol (2,4,6-TCP), pentachlorophenol (PCP), 2,4-dinitrophenol (2,4-DNP) and 2-methyl-4,6-dinitrophenol (2-M-4,6-DNP), onto sandy aquifer material at different pH values was investigated using flow through column experiments. The pH-dependent sorption of the chlorinated phenols 2,4,6-TCP and PCP was not significantly affected by DOM (measured as dissolved organic carbon, DOC), whereas in the case of nitrophenols a significant lower retardation was found, depending on the DOC concentration and pH value of the aqueous solution. Sorption decreases with increasing DOC concentration, which indicates a binding of these compounds by DOM. The degree of sorption reduction depends on the pH value and increases with increasing fraction of neutral species. The different behaviour of nitrophenols in comparison to the chlorophenols is assumed to be a result of specific charge-transfer interactions. A combined sorption and complex formation model was used to describe the effect of pH and DOC concentration on the sorption of nitrophenols onto aquifer material and to estimate binding coefficients of neutral nitrophenols on DOM.

Adsorption↗
PubMed2006

Homologue and isomer distribution of dioxins observed in water samples collected from Kahokugata Lagoon and inflowing rivers, Japan.

Water samples were collected at 17 sites in Kahokugata Water Basin, a closed water basin in central Japan. We determined the concentration of dioxins of the water samples. Linear relationships between toxic equivalent (TEQ) concentrations of dioxin and concentrations of suspended solid (SS) were obtained at sites in Kahokugata Lagoon and in the rivers flowing into the lagoon. Homologue composition of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) indicated that all the water samples were still strongly influenced by chlorinated herbicides, such as chloronitrofen (CNP) and pentachlorophenol (PCP) that had been widely used in rice fields. The main isomer distributions of the PCDD homologues were not significantly different among the sampling sites, while the main isomer distributions of the PCDF homologues were considerably different among the sampling sites. At a few sampling points in the downstream part of one of the rivers, high concentrations of 1,3,6,7,8-pentachloro dibenzofuran (1,3,6,7,8-PeCDF) and its related isomers (1,3,6,8-chlorine-substituted PCDFs) were traced to a dye manufacturing plant. These non-toxic isomers are usually only minor constituents in environmental water samples and are not indicators of any known dioxin sources. The dyeing discharge was found to make a contribution only in the water samples collected near the plant and the seasonal variation of the contribution might depend on the flow rate of the river.

Dioxins↗
PubMed2006

Effects of xenobiotics and steroids on renal and hepatic estrogen metabolism in lake trout.

Experiments were conducted to (1) elucidate the biochemical pathways of E2 metabolism in the lake trout (Salvelinus namaycush) kidney and liver, and (2) test the hypothesis that specific xenobiotics and endogenous steroids inhibit E2 metabolism by these tissues. Kidney and liver tissue fragments from immature lake trout were incubated in vitro in the presence of radiolabelled E2 plus various xenobiotics or steroids. E2 metabolites were identified by liquid chromatography/mass spectroscopy, and quantified by liquid scintillation spectroscopy. A major metabolite produced by both tissues was an unidentified hydroxylated estrogen metabolite (E2-OH) with a molecular mass of 288 that was not estriol (16-OH-E2), but possibly 7alpha-OH-E2 or 2-OH-E2 (catecholestrogen). Both tissues also produced estradiol-17-glucuronide (E2-17-G), estradiol-17-sulfate (E2-17-S), and estradiol-3-glucuronide (E2-3-G). Compared to the kidney, the liver produced half the amount of conjugated metabolites, but twofold more E2-OH. The following xenobiotics (at a concentration of 100 microM) inhibited the production of water-soluble (i.e., conjugated) E2 metabolites by both the kidney and liver: 4,4'-(OH)2-3,3',5,5'- tetrachlorobiphenyl (4,4'-OH-TCB), bisphenol A (BPA), tetrabromobisphenol A (TB-BPA), tetrachlorobisphenol A (TC-BPA), tribromophenol (TBP), trichlorophenol (TCP), and pentachlorophenol (PCP). The alkylphenols, 4-n-nonylphenol (NP), and 4-octylphenol (OP), and 2,2',4,4'-tetrabromodiphenyl ether (TBDE) had no significant effect on E2 metabolism by either tissue. Testosterone and 17alpha,20beta-dihydroxy-4-pregnen-3-one inhibited the production of conjugated E2 metabolites by both the kidney and liver. Cortisol and 11-ketotestosterone inhibited E2 metabolism by the liver only. The median inhibitory concentrations (IC50) for 4,4'-OH-TCB ranged from 7-32 microM in the kidney and 0.6-1.6 microM in the liver. For BPA, IC50's ranged from 40-108 microM in the kidney and 11-18 microM in the liver. Low doses (0.1 microM) of 4,4'-OH-TCB and BPA significantly increased estrogen metabolism in the kidney. The results suggest that certain estrogenic xenobiotics and endogenous steroids may inhibit the phase II conjugation of E2 by the kidney and liver of lake trout, and some of the known biological effects of these compounds are likely mediated, at least partially, by this mechanism of action.

Animals↗
PubMed2002

Characterization of tetrachlorohydroquinone reductive dehalogenase from Sphingomonas sp. UG30.

Tetrachlorohydroquinone reductive dehalogenase (PcpC) is the second of three enzymes that catalyze the initial degradation of pentachlorophenol in Sphingomonas sp. UG30 and several other bacterial strains. The UG30 PcpC shares a high degree (94%) of primary sequence identity with the well-studied PcpC from Sphingobium chlorophenolicum ATCC 39723. Significant differences, however, were observed between the two PcpC enzymes in some of their functional and kinetic properties. The temperature optimum of the UG30 PcpC is 10 degrees C higher and the pH optimum is approximately 2 units higher than the S. chlorophenolicum PcpC. In addition, the S. chlorophenolicum PcpC is subject to inhibition by the substrate tetrachlorohydroquinone (TCHQ), and this has necessitated the use of a mutant enzyme, which was not inhibited by TCHQ, for kinetic studies. In contrast, the UG30 PcpC was not inhibited by TCHQ and this may allow detailed kinetic and mechanistic studies using the wild-type enzyme.

Amino Acid Sequence↗
PubMed1992

Glutathione is the reducing agent for the reductive dehalogenation of tetrachloro-p-hydroquinone by extracts from a Flavobacterium sp.

Tetrachloro-p-hydroquinone is the first intermediate during pentachlorophenol degradation by Flavobacterium sp. strain ATCC 39723, a strict aerobe. We report here that tetrachlorohydroquinone was reductively dehalogenated to 2,3,6-trichloro-p-hydroquinone and subsequently to 2,6-dichloro-p-hydroquinone under anaerobic conditions by the cell extract from Flavobacterium. The reducing agent was identified to be the reduced form of glutathione. This is the first time glutathione has been identified as the reducing agent for reductive dehalogenation.

Anaerobiosis↗
PubMed1998

Characterization of thyroid hormone sulfotransferases.

Sulfation is an intriguing pathway of thyroid hormone metabolism since it facilitates the degradation of the hormone by the type I deiodinase (D1). This study reports the preliminary characterization of iodothyronine sulfotransferase activities of rat and human liver cytosol and recombinant rSULT1C1 and hSULT1A1 isoenzymes. All these enzyme preparations catalyzed the sulfation of--in decreasing order of efficiency--3,3'-diiodothyronine (3,3'-T2) > 3,3',5-triiodothyronine (T3) approximately 3,3',5'-triiodothyronine (rT3) > thyroxine (T4). 3,3'-T2 sulfotransferase activity was found to be higher in male than in female rat liver, which has also been shown by others for the expression of rSULT1A1 and rSULT1C1. No sulfation of iodothyronines was observed with rSULT1A1. Different phenol derivatives were found to be potent inhibitors of the sulfation of 3,3'-T2 by native and recombinant sulfotransferases, with pentachlorophenol and 2,4,6-tribromophenol being the most potent. The inhibitions exerted by the different phenols on 3,3'-T2 sulfation by rSULT1C1 correlated better with the effects observed in male than with those in female liver. A strong correlation was also observed between the inhibition profiles of human liver cytosol and hSUL1T1A1. These results suggest that: (1) rSULT1C1 is an important isoenzyme for the sulfation of thyroid hormone in male rat liver; (2) another isoenzyme with similar properties, perhaps rSULT1B1, is responsible for thyroid hormone sulfation in female rat liver and may also contribute to this process in male rat liver; and (3) hSULT1A1 is an important isoenzyme for thyroid hormone sulfation in human liver.

Animals↗
PubMed1987

In vitro cytotoxicity of organic pollutants to bluegill sunfish (BF-2) cells.

BF-2 cells, an established cell line derived from bluegill sunfish, (Lepomis macrochirus), were exposed to 18 organic toxicants, with cytotoxicity being assayed by the neutral red (NR) technique. Based on the concentration of toxicant that reduced lysosomal uptake of neutral red by 50% (NR50), the rank order of cytotoxicity was methyl mercury greater than pentachlorophenol greater than 2,3,5,6-tetrachlorophenol greater than 2,3,5-trichlorophenol greater than 2,3-dinitrotoluene greater than 2,4,6-trichlorophenol greater than 2,4-dichlorophenol greater than 2,4-dichlorotoluene greater than 6-chloro-3-hydroxytoluene greater than o-chlorotoluene greater than 4-chlorophenol greater than 2-chlorophenol, 2,4-dimethylphenol greater than 2,4-dinitrophenol greater than 4-nitrophenol greater than 3-methylphenol greater than phenol greater than toluene. Published in vivo LC50 values were identified for 11 of the 18 test agents and, with the exception of 2,4-dinitrophenol, there was a good correlation between the in vitro cytotoxicity of the test agents and their in vivo waterborne acute toxocity. The potencies of the substituted phenolics and chlorinated toluenes as determined by the in vitro cytotoxicity assay correlated strongly with their log octanol/water partition coefficients (log P). However, the toxicity of 2,3-dinitrotoluene in vitro, and apparently also in vivo, was not a function of its log P value.

Animals↗
PubMed1987

Physiological stress induced by sublethal concentrations of phenolic compounds in Notopterus notopterus: measurement of hydrolytic enzymes.

The studies on the effects of phenol (P), 2,4-dinitrophenol (DNP), pentachlorophenol (PCP) individually and in three combinations, viz., (PCP + DNP)/P (highly antagonistic), (DNP + P)/PCP (additive), and (P + DNP)/PCP (highly synergistic), at three sublethal levels (1/10, 1/15, and 1/20 of the 96-hr LC50) on the activity of hydrolytic enzymes (acid, alkaline, and glucose-6-phosphatases and 5-nucleotidase) in the brain and kidney of a fresh-water teleost, Notopterus notopterus revealed inhibition of enzyme activity after 15 and 30 days of exposure. Maximum inhibition (-89.32%) was observed in acid phosphatase activity in brain at 1/10 concentration of (P + DNP)/PCP combination after 30 days, but minimum (-3.64%) in activity of glucose-6-phosphatase in kidney at 1/20 of (PCP + DNP)/P combination after 15 days of exposure. However, biphasic effects of P, DNP, and (PCP + DNP)/P combination were observed in kidney, i.e., inhibition of enzymes activity at higher concentrations and stimulation at lower concentrations after both time intervals.

5'-Nucleotidase↗
PubMed2000

Determination of endocrine disruptors in water after derivatization with N-methyl-N-(tert.-butyldimethyltrifluoroacetamide) using gas chromatography with mass spectrometric detection.

The combined gas chromatographic determination of a number of hydroxyl-group containing endocrine disruptors, including 4-octylphenol, 4-nonylphenol, 2,4-dichlorophenol, pentachlorophenol, 4-tert.-butylbenzoic acid, bisphenol-A, 17beta-estradiol and 17alpha-ethynylestradiol, was investigated. Derivatization, required for sensitive determination of these compounds, was carried out using N-methyl-N-(tert.-butyldimethyltrifluoroacetamide). A number of parameters affecting the derivatization reaction, like temperature, time, matrix, solvent, and amount of reagent were studied in detail. Quantitative yields were obtained for real-life extracts after optimization, but the hormones were only mono-substituted. Both solid-phase extraction (SPE) and liquid-liquid extraction were studied as extraction methods, with emphasis on SPE material and effect of pH. Recoveries and RSD for analysis of surface water samples were 58-106 and 6-16% (n=4), respectively, when using SPE, and 109-117 and 6-14% (n=6) when using liquid-liquid extraction. The method developed allows routine analysis of surface water for traces of endocrine disruptors. The limits of detection of were 4-6 ng/l but higher for the hormones.

Endocrine Glands↗
PubMed2000

Solid-phase extraction of acidic herbicides.

A discussion of solid-phase extraction method development for acidic herbicides is presented that reviews sample matrix modification, extraction sorbent selection, derivatization procedures for gas chromatographic analysis, and clean-up procedures for high-performance liquid chromatographic analysis. Acidic herbicides are families of compounds that include derivatives of phenol (dinoseb, dinoterb and pentachlorophenol), benzoic acid (acifluorfen, chloramben, dicamba, 3,5-dichlorobenzoic acid and dacthal--a dibenzoic acid derivative), acetic acid [2,4-dichlorophenoxyacetic acid (2,4-D), 4-chloro-2-methylphenoxyacetic acid (MCPA) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T)], propanoic acid [dichlorprop, fluazifop, haloxyfop, 2-(4-chloro-2-methylphenoxy)propanoic acid (MCPP) and silvex], butanoic acid [4-(2,4-dichlorophenoxy)butanoic acid (2,4-DB) and 4-(4-chloro-2-methylphenoxy)butanoic acid (MCPB)], and other miscellaneous acids such as pyridinecarboxylic acid (picloram) and thiadiazine dioxide (bentazon).

Chromatography, Gas↗
PubMed2000

Potential artifact formation of dioxins in ball clay during supercritical fluid extraction.

Earlier surveys indicate that meat, fish and dairy products are the principal source of polychlorinated dibenzo-p-dioxin (PCDD) exposure in the diet. A recent finding by others of PCDDs in chickens that consumed a feed containing PCDD led to the finding of ball clay, an anti-caking agent, as the source. Supercritical fluid extraction (SFE) was studied as a means to isolate PCDDs from commercial ball clays using GC-electron capture detection (muECD) as a means to screen for these contaminants. The finding of ng/g amounts and recoveries >100% in several samples of ball clay containing octachlorodibenzo-p-dioxin (OCDD) suggested that PCDD may form artifactually as a result of analysis. Studies on pentachlorophenol (PCP) fortified ball clay were carried out by SFE and soxhlet extraction and the results compared. The values obtained by SFE were considered more problematic. The results obtained from ball clay suggest that precautions need to be exercised when using SFE to analyze for dioxins in solid samples containing chlorophenols.

Animal Feed↗
PubMed1990

Use of polymeric sorbents for the off-line preconcentration of priority pollutant phenols from water for high-performance liquid chromatographic analysis.

The use of porous polymeric minicolumns for the determination of phenols from the U.S. Environmental Priority Pollutant List was studied. For the off-line preconcentration of priority pollutant phenols from water by solid-phase extraction, minicolumns packed with 1,4-di(methacryloyloxymethyl)naphthalene-divinylbenzene copolymer and Amberlite XAD-4 were used. In order to compare the sorption properties of these polymeric sorbents, the recoveries and breakthrough volumes of phenol, p-nitrophenol, 2,4-dinitrophenol, o-chlorophenol, o-nitrophenol, 2,4-dimethylphenol, 4-chloro-m-cresol, 4,6-dinitro-o-cresol, 2,4-dichlorophenol, 2,4,6-trichlorophenol and pentachlorophenol were studied.

Acrylates↗
PubMed1997

Analytical methods for the determination of organochlorine compounds. Application to environmental samples in the Slovak Republic.

The paper deals with the isolation of chlorinated phenols, benzenes and insecticides from water, soil and vegetable samples. A review of the current procedures is presented. Solid-phase extraction on Empore extraction discs was experimentally evaluated for isolation of the compounds from surface and ground waters. For the isolation of chlorophenols from soil and vegetable samples, a method of simultaneous steam distillation/extraction was elaborated which proved to be also applicable for waste waters and sludges. Chlorinated insecticides and benzenes were extracted from soil and vegetable samples with the Soxhlet procedure. Final determinations were carried out by GC-electron-capture detection. The recoveries of the methods were well over 70%, with relative standard deviations below 14%. Samples of surface and ground waters, soil and vegetables, mostly from the vicinity of chemical and municipal waste dumping sites, were analysed. The highest contamination levels were found for chlorinated phenols in surface water from the vicinity of a former chemical waste dumping place where the concentrations of 2,6-dichlorophenol and pentachlorophenol were 4.3 and 3.9 micrograms l-1, respectively.

Benzene↗
PubMed1999

Discrimination of structural isomers of chlorinated phenols in waters using gas chromatography-mass spectrometry in the negative chemical ionization mode.

The analysis and identification of structural isomers of mono-, di- and trichlorophenols is reported. The fragmentation of the phenols was examined by GC-MS in both electron impact (EI) and negative chemical ionization (NCI) modes, using methane as reagent gas. The ability of NCI to discriminate these isomeric compounds from differences in relative intensities for selected peaks is demonstrated. 3- and 4-chlorophenols have similar retention times; however, they can still be discriminated because their negative mass spectra and rather different. In dichlorophenols, the presence of one chlorine atom in the ortho position decreases their retention time and the relative intensity of the fragment ion at m/z 140. The NCI mass spectra for trichlorophenols are different from the rest, particularly for the m/z value corresponding to the chlorine atom. Tetra- and pentachlorophenols were also studied and sequential losses of Cl observed. An automatic solid-phase extraction system can optionally be used to preconcentrate chlorophenols in waters prior to determination at legally established toxic levels.

Gas Chromatography-Mass Spectrometry↗
PubMed1999

Synthesis and analytical properties of a novel columnar metallomesogenic polymer.

A metallomesogenic side-chain polymer with copper carboxylato discotic units in stacks prepared by covalent bonding of 14-pentadecenoic acid, stearic acid and poly(methylhydrosiloxane) is described. The physico-chemical and thermal properties of both monomeric and polymeric metallomesogens were determined by elemental analysis, IR, polarizing optical microscopy, thermal gravimetric analysis and differential scanning calorimetry. The polymeric states showed a discotic lamellar phase at 50-95 degrees C and an ordered discotic hexagonal phase at 95-200 degrees C. By dynamic coating, the metallomesogenic polymer was crosslinked to the capillary wall via benzoyl peroxide. The wall-coated capillary columns (15 m x 0.25 mm I.D.) were used for the separation of phenols. Factors affecting the retention and the sample selectivity were examined. Van 't Hoff plots as a function of temperature indicated that phase transitions were occurring. Thermodynamic properties of the analytes in this system were also studied. For the determination of a mixture of 3-aminophenol, 2-chlorophenol, 2-nitrophenol, 4-nitrophenol, o-methylphenol, m-methylphenol, p-methylphenol, 2,4-dichlorophenol, 2,4-dimethylphenol, 2,4-dinitrophenol, 2,4,6-trichlorophenol, 2,4,6-trimethylphenol, 4-bromophenol, 3-methyl-4-chlorophenol, pentachlorophenol, and unsubstituted phenol, the calibration graphs for most phenols were linear over the range of 10-1000 microg ml(-1) and the mass detection limits were in the ng range based on three times standard deviation of seven measurements of the lowest peak that could be detected.

Calorimetry, Differential Scanning↗
PubMed2003

Biodegradation of toxic chemicals in Guayanilla Bay, Puerto Rico.

Studies were conducted to assess the factors that may influence the rate and extent of biodegradation of biphenyl, naphthalene, phenanthrene, pentachlorophenol (PCP) and p-nitrophenol in water samples collected from the Guayanilla Bay (18 degrees N; 67.45 degrees W), southwest of Puerto Rico. In vitro studies mediated slow degradation of biphenyl, naphthalene and phenanthrene substrates by natural microbial flora present in the Bay. Addition of KNO(3) as a source of inorganic N greatly enhanced the degradation of phenanthrene but not of naphthalene, suggesting that effects on degradation due to nutrient limitation were compound specific. The rate and extent of degradation of naphthalene and PCP were higher in water samples collected closer to the source of contamination, i.e. the petrochemical complex. The identity of a phenanthrene degrading bacterium, previously identified by conventional phenotypic method (Zaidi et al., Utilizing Nature's Advanced Materials, Oxford Unviersity Press, 1999) as Alteromonas sp., was confirmed by partial DNA sequencing of the small subunit rRNA gene.

Biodegradation, Environmental↗