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Degradation Compounds (degradation + compound)
Selected AbstractsKinetic monitoring of trisubstituted organotins in soil after sewage sludge applicationAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 9 2008S. Dubascoux Abstract Organotin compounds (OTC) are widely used for their biocidal effects in various agricultural or industrial activities, leading to their environmental presence. Among the organotin species, tributyltin (TBT) and triphenyltin (TPhT) are the most used and are generally considered the most toxic. So it is important to understand their behaviour in soils and obtain data about their persistence and phytoavailability. Many works deal with OTC speciation in various matrices, but few are concerned with OTC degradation in soil. The present study focuses on kinetic monitoring of TBT and TPhT in an agricultural soil. These compounds were introduced into the soil by the way of spiked sewage sludge, simulating agricultural practice and diffuse contamination. The influence of time and initial OTC concentration on the species preservation was evaluated. TBT concentration was shown to have a positive effect on TBT preservation. Corresponding half-lives were calculated. They were 6 ± 1 days and over 39 days for TPhT and TBT, respectively. Degradation compounds, mono- and dibutyltin, and mono- and diphenyltin, were produced by both direct and successive dealkyl and dearylation processes. Copyright © 2008 John Wiley & Sons, Ltd. [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] Loss of tocopherols and formation of degradation compounds at frying temperatures in oils differing in degree of unsaturation and natural antioxidant contentJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2002Daniel Barrera-Arellano Abstract Samples of oils of different degrees of unsaturation, namely palm olein, olive oil, high-linoleic sunflower oil, high-oleic sunflower oil, rapeseed oil and soybean oil, were heated at 180,°C for 2, 4, 6, 8 and 10,h in the presence or absence of their natural antioxidants. Also, tocopherol-stripped oils were supplemented with ,-tocopherol (500,mg,kg,1), ,-tocopherol (500,mg,kg,1) or a mixture of ,-, ,-, ,- and ,-tocopherols (250,mg,kg,1 each) and heated under the same conditions. Losses of tocopherols and formation of polymeric triacylglycerols were followed. Total polar compounds were also evaluated after 10,h of heating. Results demonstrated that tocopherols were lost very rapidly, in the expected order, with ,-tocopherol being the least stable. Polymeric and polar compound formation during heating was inhibited to a variable extent, being more dependent on the natural content and type of tocopherols than on the degree of unsaturation of the oil. For example, polymeric and polar compound contents in soybean oil were significantly lower than those found in high-linoleic sunflower oil. However, the expected influence of the degree of unsaturation was evident when oils were unprotected or possessed identical initial antioxidant contents. Finally, levels of degradation compounds after 10,h of heating were not dependent on the remaining content of antioxidants. © 2002 Society of Chemical Industry [source] Behaviour of sulcotrione and mesotrione in two soilsPEST MANAGEMENT SCIENCE (FORMERLY: PESTICIDE SCIENCE), Issue 1 2008Hančne Chaabane Abstract The behaviour of sulcotrione, a recently introduced triketone herbicide, in various soil types was studied under laboratory conditions. In particular, degradation and sorption processes were examined on Ghent and Perpignan soils. Kinetics showed that the degradation of sulcotrione was influenced by biotic and/or abiotic factors. Half-lives ranged between 45 and 65 days. Among the degradation compounds identified were 1,3-cyclohexanedione (CHD) and 2-chloro-4-mesyl benzoic acid (CMBA), previously described as hydrolysis products, and, under special conditions, a derivative of phenylheptanoic acid (PHD). This new degradation product suggested that sulcotrione could follow two possible pathways in the soil, as in water. During the sorption study, a moderate retention of sulcotrione and CMBA relative to CHD and PHD, which were highly adsorbed whatever the soil type, was reported. Experiments carried out under the same conditions for sulcotrione and mesotrione, another triketone herbicide recommended in maize culture, made it possible to compare the two triketones and to conclude that they exhibited relatively similar behaviour in the soil, i.e. that their leaching potential needs to be properly addressed and risks evaluated. Copyright © 2007 Society of Chemical Industry [source] High-performance liquid chromatography with electrospray ionisation mass spectrometry and diode array detection in the identification and quantification of the degradation products of calix[4]arene crown-6 under radiolysisRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 13 2004C. Lamouroux The extraction of 135Cs from high-activity liquid waste, arising from reprocessing of spent nuclear fuel, can be achieved by using calix[4]arene crown-6 compounds. The radiolytic degradation of di(n-octyloxy)calix[4]arene crown-6 (octMC6), in aliphatic or aromatic solvent in contact with 3 M nitric acid, was studied by high-performance liquid chromatography directly coupled to electrospray ionisation mass spectrometry (LC/ESI-MS). More than 50 distinct degradation products were observed, and about 30 of these were identified. These compounds can be assigned to three categories, namely, products of reactions involving radical cleavage or addition, of oxidation reactions, or of aromatic substitution reactions. The major product, corresponding to substitution by an NO2 group, was quantified by external standard calibration using a purified synthetic sample. Despite the observation of all these degradation compounds, octMC6 appears to be remarkably stable under these drastic conditions, combining hydrolysis (HNO3 3,M) and an extreme exposure to radiolysis (106,Gy). Less than 35% degradation of octMC6 was observed in aromatic solvent under these conditions. Copyright © 2004 John Wiley & Sons, Ltd. [source] | ||||||||||