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Transformation Products (transformation + products)
Selected AbstractsA review of in situ measurement of organic compound transformation in groundwater,,PEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 4 2001Sharon K Papiernik Abstract Laboratory assessments of the rate of degradation of organic compounds in groundwater have been criticized for producing unrepresentative results. The potential for organic compounds to be transformed in groundwater has been measured using in situ methods, which avoid problems of attempting to duplicate aquifer conditions in the laboratory. In situ assessments of transformation rates have been accomplished using transport studies and in situ microcosms (ISMs); a review of these methods is given here. In transport studies, organic solutes are injected into an aquifer and the concentrations are monitored as they are transported downgradient. The change in mass of a solute is determined by the area contained under the breakthrough curve (plot of concentration versus time). ISMs isolate a portion of the aquifer from advective flow and act as in situ batch reactors. Experiments using ISMs involve removing water from the ISM, amending it with the solutes of interest, re-injecting the amended water, and monitoring the solute concentrations with time. In both transport and ISM studies, the loss of organic solutes from solution does not allow a distinction to be made between sorptive, abiotic and biotic transformation losses. Biological activity can be chemically suppressed in ISMs and the results from those experiments used to indicate sorption and abiotic loss. Transformation products may be monitored to provide additional information on transformation mechanisms and rates. Published in 2001 for SCI by John Wiley & Sons, Ltd [source] Roxarsone and transformation products in chicken manure: Determination by capillary electrophoresis-inductively coupled plasma-mass spectrometryELECTROPHORESIS, Issue 7-8 2005Charlita G. Rosal Abstract The determination of the animal feed additive roxarsone (3-nitro-4-hydroxyphenylarsonic acid) and six of its possible transformation products (arsenite, arsenate, monomethylarsonate, dimethylarsinate, 3-amino-4-hydroxyphenylarsonic acid, and 4-hydroxyphenylarsonic acid) in chicken manure was investigated using capillary electrophoresis-inductively coupled plasma-mass spectrometry (CE-ICP-MS). Initial method development was conducted using ultraviolet (UV) detection for ruggedness and time efficiency. Separation of these seven arsenic species was effected using a 20,mM phosphate buffer at pH 5.7. The CE-ICP-MS limits of detection in terms of As for each of the species was in the low µg·L,1 range, corresponding to absolute detection limits in the range 20,70,fg As (based on a 23,nL injection). Overall, the method developed in this study provides high selectivity and low limits of detection (1,3,µg·L,1 or low-ppb, based on As), uses small sample volume (low nL), and produces minimal wastes. [source] Environmental concentrations of methoprene and its transformation products after the treatment of Altosid® XR Briquets in the city of Richmond, British Columbia, CanadaENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2010Jen-ni Kuo Abstract Water runoff from catch basins treated with Altosid® XR Briquets for mosquito larvae control was sampled at 10 storm drainage pump stations along the outskirts of the city of Richmond, British Columbia, Canada after rainfall events in 2006 to determine the residual concentrations of methoprene and transformation products: citronellic acid, methoprene acid, and 7-methoxycitronellic acid. Runoff of prior-to-treatment, posttreatment, and 150-d-after-treatment was collected. No residues were detected in the prior-to-treatment samples. However, methoprene was detected in posttreatment, and citronellic acid was detected in posttreatment and one 150-d-after-treatment sample. The detected environmental concentrations of methoprene (0.04,0.14,µg/L) and methoprene acid (0.07,µg/L) at pump stations were below known/reported toxicity values to aquatic organisms. However, concentrations detected inside the storm drainage system in catch basins (methoprene 122,µg/L, methoprene acid 1.74,µg/L) and inspection chambers (methoprene 622,µg/L, methoprene acid 20,µg/L, citronellic acid 0.05,µg/L) are known to be toxic to invertebrates, have chronic early-life-stage fish effects, and exceeded the Draft Interim Ontario Water Quality Objective and the numerical benchmarks for protection of amphibians (1.6,µg/L), invertebrates (10,µg/L), and fish (80,µg/L). The limited detection in the present study may have resulted from significant absorption of methoprene to sample bottle walls, substance decay during sample storage before methoprene extraction, flushing of briquettes from catch basins following heavy rainfall, and the burial of briquettes under thick layers of debris. Environ. Toxicol. Chem. 2010;29:2200,2205. © 2010 SETAC [source] Toxicological characterization of 2,4,6-trinitrotoluene, its transformation products, and two nitramine explosivesENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2007Judith Neuwoehner Abstract The soil and groundwater of former ordnance plants and their dumping sites have often been highly contaminated with the explosive 2,4,6-trinitrotoluene (2,4,6-TNT) leading to a potential hazard for humans and the environment. Further hazards can arise from metabolites of transformation, by-products of the manufacturing process, or incomplete combustion. This work examines the toxicity of polar nitro compounds relative to their parent compound 2,4,6-TNT using four different ecotoxicological bioassays (algae growth inhibition test, daphnids immobilization test, luminescence inhibition test, and cell growth inhibition test), three genotoxicological assays (umu test, NM2009 test, and SOS Chromotest), and the Ames fluctuation test for detection of mutagenicity. For this study, substances typical for certain steps of degradation/transformation of 2,4,6-TNT were chosen for investigation. This work determines that the parent compounds 2,4,6-TNT and 1,3,5-trinitrobenzene are the most toxic substances followed by 3,5-dinitrophenol, 3,5-dinitroaniline and 4-amino-2-nitrotoluene. Less toxic are the direct degradation products of 2,4,6-TNT like 2,4-dinitrotoluene, 2,6-dinitrotoluene, 2-amino-4,6-dinitrotoluene, and 4-amino-2,6-dinitrotoluene. A weak toxic potential was observed for 2,4,6-trinitrobenzoic acid, 2,4-diamino-6-nitrotoluene, 2,4-dinitrotoluene-5-sulfonic acid, and 2,6-diamino-4-nitrotoluene. Octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine and hexahydro-1,3,5-trinitro-1,3,5-triazine show no hint of acute toxicity. Based on the results of this study, we recommend expanding future monitoring programs of not only the parent substances but also potential metabolites based on conditions at the contaminated sites and to use bioassays as tools for estimating the toxicological potential directly by testing environmental samples. Site-specific protocols should be developed. If hazardous substances are found in relevant concentrations, action should be taken to prevent potential risks for humans and the environment. Analyses can then be used to prioritise reliable estimates of risk. [source] Toxicity and fate of two munitions constituents in spiked sediment exposures with the marine amphipod Eohaustorius estuariusENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 11 2005Gunther Rosen Abstract The lethal toxicity of the explosive compounds 14C-labeled 2,4,6-trinitrotoluene (TNT) and nonradiolabeled hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) to the estuarine amphipod Eohaustorius estuarius was investigated in 10-d spiked sediment exposures. The 10-d median lethal concentration (LC50) was determined using the sum molar initial concentration of TNT, ami-nodinitrotoluenes (ADNTs), and diaminonitrotoluenes (DANTs), as determined by high-performance liquid chromatography (HPLC), and collectively referred to as HPLC-TNT*. Despite expectations of higher toxicity in sandy sediment (Yaquina Bay [YB], OR, USA) compared to relatively fine-grained sediment (San Diego Bay [SDB], CA, USA), LC50 values were similar: 159 and 125 ,mol/kg, for YB and SDB sediments, respectively. When expressed as the sum of TNT and all its degradation products (14C-TNT*), LC50s were approximately two times the corresponding LC50s determined by HPLC. The HPLC-TNT* fraction likely corresponds to the most bioavailable and toxic transformation products. The concentrations of 14C-TNT* in tissues were substantially higher than those for HPLC-TNT*, suggesting that compounds other than TNT and its major aminated transformation products were prevalent. Critical body residues were similar for exposures to SDB (11.7 ,mol/kg) and YB sediments (39.4 ,mol/kg), despite marked differences in the nature of compounds available for uptake in the exposure media. The critical body residues for E. estuarius are lower than those reported for other aquatic invertebrates (83,172 ,mol/kg). Unlike observations for TNT, RDX was only loosely associated with SDB sediment, with near complete recovery of the parent compound by chemical analysis. Exposure to RDX did not result in significant mortality even at the highest measured sediment concentration of 10,800 ,mol/kg dry weight, nor tissue concentrations as high as 96 ,mol/kg wet weight. The lack of RDX lethal effects in this study is consistent with results reported for other invertebrate species. [source] Mutagenicity of nitroaromatic degradation compoundsENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2003Ranjit S. Padda Abstract The mutagenicity of 2,4-dinitrotoluene (24DNT), and 2,6-dinitrotoluene (26DNT), and their related transformation products such as hydroxylamine and amine derivatives, which are formed by Clostridium acetobutylicum, were tested in crude cell extracts using Salmonella typhimurium TA100. A previous publication already reported the mutagenic activities of 2,4,6-trinitrotoluene (TNT) and its related hydroxylamine derivatives in this test system. A time course of the mutagenicity during the anaerobic transformation of TNT, 24DNT, and 26DNT was also investigated under the same conditions to compare with the results from the pure compounds. The monohydroxylamino intermediates 2-hydroxylamino-4-nitrotoluene (2HA4NT), 4-hydroxylamino-2-nitrotoluene (4HA2NT) and 2-hydroxylamino-6-nitrotoluene (2HA6NT) formed during anaerobic transformation of dinitrotoluenes were proven to be mutagenic in the Ames test using Salmonella typhimurium TA100. This study reports that 4HA2NT is the most stable derivative, whereas 2HA4NT and 2HA6NT are less stable and these intermediates are mutagenic in the Ames test. Both 24DNT and 26DNT and their final metabolites 2,4-diaminotoluene (24DAT) and 2,6-aminotoluene (26DAT) appeared nonmutagenic. In a time-course study of TNT degradation, the temporal sample containing 85% of 2,4-dihydroxylamino-6-nitrotoluene (24HA6NT) is most mutagenic. These observations suggest that the bioremediation approach for treatment of 24DNT and 26DNT should be carried past the hydroxylamino intermediate. [source] Trichlorofluoroethene: A reactive tracer for evaluating reductive dechlorination in large-diameter permeable columnsGROUND WATER MONITORING & REMEDIATION, Issue 2 2005Jennifer A. Field Trichlorofluoroethene (TCFE) was used as a reactive tracer to determine the in situ rate of reductive dechlorination in treatment zones impacted by three large-diameter permeable columns (LDPCs) that were installed at a trichloroethene (TCE),contaminated site. The LDPCs were part of a pilot study to evaluate the effectiveness of hydrogen, lactate, and zero-valent iron for remediating TCE-contaminated ground water. The rate of TCFE reductive dechlorination was determined for each LDPC by means of push-pull tests conducted in each treatment layer. In addition, the distribution of TCFE's lesser chlorinated transformation products was determined. The rates of TCFE reductive dechlorination ranged from 0.05/d to 0.20/d and corresponded to half-lives ranging from 3.5 to 13.9 d. cis -Dichlorofluoroethene was the dominant transformation product detected in all the tests, which is consistent with the findings from pilot tests conducted in the LDPCs prior to the TCFE push-pull tests. cis -Chlorofluoroethene (CFE) and 1,1-CFE also were detected and indicate the potential for vinyl chloride to form under all treatment regimes. Significant production of fluoroethene (FE), the analog of ethene, was observed for only one of the hydrogen treatments. Unambiguous and sensitive detection of the lesser chlorinated products, such as CFE and FE, is possible because TCFE and its transformation products are not found in the background ground water at contaminated sites. Good agreement between the rates and transformation product profiles for TCFE and TCE in both field and laboratory experiments indicates the suitability of TCFE as a surrogate for predicting the rates of TCE reductive dechlorination. [source] Ring transformations of heterocyclic compounds.JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 2 20022,4,6-Triarylpyrylium perchlorates 1 react with methyleneindolines 3in situ generated from the corresponding methylindolium salts 2, which are spiro-fused with a cycloalkane, benzanellated cycloalkene or a heterocyclic system. These diastereoselective 2,5-[C4+C2] pyrylium ring transformations are carried out in the presence of triethylamine/acetic acid in boiling ethanol to give the dispiroindolines 4 with a trans configuration of the more bulky substituents at the cyclohexadiene ring. By the same type of transformation the dispiro compounds 7/10 with an additional fused benzene ring are obtained from the pyrylium salt 1a and 6/9, the benzo-fused analogues of 3. Spectroscopic data of the transformation products as well as their mode of formation are discussed. [source] Ring transformations of heterocyclic compounds.JOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 2 2002The synthesis of pyrido[1,2- a]indolium perchlorates 8,11 from 2,4,6-triarylpyrylium perchlorates 1 and 2-methyl-3H -indoles 6,9 in the presence of a basic condensing agent (anhydrous sodium acetate, piperidine acetate, triethylamine/acetic acid, triethylamine) in ethanol by a 2,4-[C3+C2N] pyrylium ring transformation is reported. Spectroscopic data of the transformation products and their mode of formation are discussed. [source] Investigating the presence of pesticide transformation products in water by using liquid chromatography-mass spectrometry with different mass analyzers,JOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 2 2008Félix Hernįndez Abstract Many pesticide transformation products (TPs) can reach environmental waters as a consequence of their normally having a higher polarity than their parent pesticides. This makes the development of analytical methodology for reliable identification and subsequent quantification at the sub-microgram per liter levels necessary, as required under current legislation. In this paper we report the photodegradation of several pesticides frequently detected in environmental waters from the Spanish Mediterranean region using the high-resolution and exact-mass capabilities of hybrid quadrupole time-of-flight mass spectrometry (QTOF MS) hyphenated to liquid chromatography (LC). Once the main photodegradation/hydrolysis products formed in aqueous media were identified, analytical methodology for their simultaneous quantification and reliable identification in real water samples was developed using on-line solid-phase extraction (SPE)-LC-tandem MS with a triple-quadrupole (QqQ) analyzer. The methodology was validated in both ground and surface water samples spiked at the limit of quantification (LOQ) and 10 × LOQ levels, i.e. 50 and 500 ng/l, obtaining satisfactory recoveries and precision for all compounds. Subsequent analysis of ground and surface water samples resulted in the detection of a number of TPs higher than parent pesticides. Additionally, several soil-interstitial water samples collected from the unsaturated zone were analyzed to explore the degradation/transformation of some pesticides in the field using experimental plots equipped with lisimeters. Several TPs were found in these samples, with most of them having also been detected in ground and surface water from the same area. This paper illustrates the extraordinary potential of LC-MS(/MS) with QTOF and QqQ analyzers for qualitative/structural and quantitative analysis, respectively, offering analytical chemists one of the most powerful tools available at present to investigate the presence of pesticide TPs in water. Copyright © 2007 John Wiley & Sons, Ltd. [source] Mass spectrometry of the photolysis of sulfonylurea herbicides in prairie watersMASS SPECTROMETRY REVIEWS, Issue 4 2010John V. Headley Abstract This review of mass spectrometry of sulfonylurea herbicides includes a focus on studies relevant to Canadian Prairie waters. Emphasis is given to data gaps in the literature for the rates of photolysis of selected sulfonylurea herbicides in different water matrices. Specifically, results are evaluated for positive ion electrospray tandem mass spectrometry with liquid chromatography separation for the study of the photolysis of chlorsulfuron, tribenuron-methyl, thifensulfuron-methyl, metsulfuron-methyl, and ethametsulfuron-methyl. LC,MS/MS is shown to be the method of choice for the quantification of sulfonylurea herbicides with instrumental detection limits ranging from 1.3 to 7.2,pg (on-column). Tandem mass spectrometry coupled with the use of authentic standards likewise has proven to be well suited for the identification of transformation products. To date, however, the power of time-of-flight MS and ultrahigh resolution MS has not been exploited fully for the identification of unknown photolysis products. Dissipation of the herbicides under natural sunlight fit pseudo-first-order kinetics with half-life values ranging from 4.4 to 99 days. For simulated sunlight, radiation wavelengths shorter than 400,nm are required to induce significant photolytic reactions. The correlation between field dissipation studies and laboratory photolysis experiments suggests that photolysis is a major pathway for the dissipation of some sulfonylurea herbicides in natural Prairie waters. © 2009 Wiley Periodicals, Inc., Mass Spec Rev 29:593,605, 2010 [source] Characterization of atenolol transformation products on light-activated TiO2 surface by high-performance liquid chromatography/high-resolution mass spectrometryRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 1 2009Claudio Medana No abstract is available for this article. [source] Biotransformation of the triketone herbicide mesotrione by a Bacillus strain.RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 17 2006Metabolite profiling using liquid chromatography/electrospray ionization quadrupole time-of-flight mass spectrometry The metabolic pathway involved in the biotransformation of the herbicide mesotrione by the bacterial strain Bacillus sp. 3B6 was investigated by a reliable liquid chromatography/electrospray ionization quadrupole time-of-flight mass spectrometry (LC/ESI-QTOF-MS) method. The LC/ESI-MS method, both in positive and negative mode, with the assistance of MS2 fragments and isotopic pattern analyses, allowed us to identify five metabolites. This work constitutes the first complete monitoring of mesotrione degradation kinetics. Among the transformation products found by both techniques, one was formed by intramolecular cyclization between a hydroxylamine and a keto function, which is quite a rare biological reactivity process. For each identified metabolite, a fragmentation pathway is proposed for negative and positive mode. Copyright © 2006 John Wiley & Sons, Ltd. [source] Formation of Furfural in Catalytic Transformation of Levoglucosan over Mesoporous MaterialsCHEMCATCHEM, Issue 5 2010M. Käldström Abstract Catalytic transformations of levoglucosan (1-6-anhydro-,- D -glucopyranose) and furfural were carried out in a fixed-bed reactor at 573,K over mesoporous materials. Proton forms of MCM-41, MCM-48, SBA-15, and platinum form of MCM-48 catalysts were tested in the reaction, whereas H-Beta and quartz sand were used as reference materials. The yield of the transformation products was substantially influenced by the catalyst structures. Oxygenated species were the main liquid products, consisting mainly of aldehydes and furfural. The formation of furfural was the highest over MCM-41 catalyst followed by SBA-15, MCM-48, and H-Beta catalyst. All catalysts were to some extent deactivated due to coke formation. However, it was possible to successfully regenerate the spent catalysts without changing the structure. [source] | |||||||||||||