Determination Of Transformation Products Research Articles

Fate of phthalate esters in landfill leachate under subcritical and supercritical conditions and determination of transformation products

The hypothesis of this study is that the complex organic load of landfill leachate could be reduced by supercritical water oxidation (SCWO) in a single stage, but this operation could lead to the formation of some undesired by-products of phthalate esters (PAEs). In this context, the fate of selected PAEs, butyl benzyl phthalate (BBP), di-2-ethylhexyl phthalate (DEHP) and di-n-octyl phthalate (DNOP), was investigated during the oxidation of leachate under subcritical and supercritical conditions. Experiments were conducted at various temperatures (250–500 °C), pressures (10–35 MPa), residence times (2–18 min) and dimensionless oxidant doses (DOD: 0.2–2.3). The SCWO process decreased the leachate’s chemical oxygen demand (COD) from 34,400 mg/L to 1,120 mg/L (97%). Removal efficiencies of DEHP and DNOP with longer chains were higher than BBP. The DEHP, DNOP and BBP compounds were removed in the range of −35 to 100%, −18 to 92%, and 28 to 36%, respectively, by the SCWO process. Many non-target PAEs were qualitatively detected in the raw leachate apart from the selected PAEs. Besides, 97% of total PAEs including both target and non-target PAEs was mineralized at 15 MPa, 300 °C and 5 min. Although PAEs were highly mineralized during SCWO of the leachate, aldehyde, ester, amide and amine-based phthalic substances were frequently detected as by-products. These by-products have transformed into higher molecular weight by-products with binding reactions as a result of complex SCWO process chemistry. It has also been determined that some non-target PAEs such as 1,2-benzenedicarboxylic acid bis(2-methylpropyl)ester and bis(2-ethylhexyl) isophthalate can transform to the DEHP. Therefore, the suggested pathway in this study for PAEs degradation during the SCWO of the leachate includes substitution and binding reactions as well as an oxidation reaction.

Anaerobic biodegradation of dipyrone: Determination of transformation products by LC-HRMS and ecotoxicity assessment using target organisms and QSAR model

The degradation of dipyrone (metamizole) was studied for the first time under mesophilic anaerobic conditions using a synthetic wastewater similar to that found in anaerobic digestion (AD) treatment plants. Dipyrone concentration effect (250–25,000 µg L−1) was evaluated in short term batch and long-term semi-continuous operation. After 48 days, biogas production and biodegradability were reduced in the batch AD by 17.7% and 18.8%, respectively, regardless of the dipyrone concentration. However, additions of 1000 µg L−1 to the long-term AD system stimulated biogas production and increased organic matter removal by 68% and 30%, respectively. Although removals of the main metabolite 4-MAA (N-methyl-4-aminoantipyrine) and other transformation products were observed in the batch tests after 48 days, a continuous accumulation of dipyrone by-products in the long-term AD reflected its recalcitrant nature. The occurrence of these metabolites coincided with an increased toxicity of the AD effluent to Aliivibrio fischeri of 79% bioluminescent bacteria-inhibition observed immediately after the addition of the dipyrone, while the germination of Lactuca sativa seeds and growth of Raphidocelis subcaptata were stimulated by the same conditions. The toxicity of by-products was mainly attributed to hydrazinic group according to predictions elaborated by ECOSAR software. The results showed that long term exposure to dipyrone main by-product 4-MAA, as a consequence of build up into environment over continuous discharges of effluents, can significantly affect freshwater organisms.

Anaerobic Biodegradation of Dipyrone: Determination Of Transformation Products by Lc-Hrms and Ecotoxicityassessment Using Target Organisms and Qsar Model

Anaerobic Biodegradation of Dipyrone: Determination Of Transformation Products by Lc-Hrms and Ecotoxicityassessment Using Target Organisms and Qsar Model

Quantification of transformation products of rocket fuel unsymmetrical dimethylhydrazine in soils using SPME and GC-MS

Determination of transformation products (TPs) of rocket fuel unsymmetrical dimethylhydrazine (UDMH) in soil is highly important for environmental impact assessment of the launches of heavy space rockets from Kazakhstan, Russia, China and India. The method based on headspace solid-phase microextraction (HS SPME) and gas chromatography-mass spectrometry is advantageous over other known methods due to greater simplicity and cost efficiency. However, accurate quantification of these analytes using HS SPME is limited by the matrix effect. In this research, we proposed using internal standard and standard addition calibrations to achieve proper combination of accuracies of the quantification of key TPs of UDMH and cost efficiency. 1-Trideuteromethyl-1H-1,2,4-triazole (MTA-d3) was used as the internal standard. Internal standard calibration allowed controlling matrix effects during quantification of 1-methyl-1H-1,2,4-triazole (MTA), N,N-dimethylformamide (DMF), and N-nitrosodimethylamine (NDMA) in soils with humus content < 1%. Using SPME at 60 °C for 15 min by 65 µm Carboxen/polydimethylsiloxane fiber, recoveries of MTA, DMF and NDMA for sandy and loamy soil samples were 91–117, 85–123 and 64–132%, respectively. For improving the method accuracy and widening the range of analytes, standard addition and its combination with internal standard calibration were tested and compared on real soil samples. The combined calibration approach provided greatest accuracies for NDMA, DMF, N-methylformamide, formamide, 1H-pyrazole, 3-methyl-1H-pyrazole and 1H-pyrazole. For determination of 1-formyl-2,2-dimethylhydrazine, 3,5-dimethylpyrazole, 2-ethyl-1H-imidazole, 1H-imidazole, 1H-1,2,4-triazole, pyrazines and pyridines, standard addition calibration is more suitable. However, the proposed approach and collected data allow using both approaches simultaneously.

Elucidation of transformation pathway of ketoprofen, ibuprofen, and furosemide in surface water and their occurrence in the aqueous environment using UHPLC-QTOF-MS

The identification and determination of transformation products (TPs) of pharmaceuticals is essential nowadays, in order to track their fate in the aqueous environment and, thus, to estimate the actual pollution. However, this is a challenging task due to the necessity to apply high-resolution instruments enable to detect known and unknown compounds. This work presents the use of liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF-MS) as a powerful tool for the identification of three selected pharmaceuticals, furosemide (FUR), ibuprofen (IBP), and ketoprofen (KET), and their TPs in various water samples. Laboratory degradation experiments were performed using xenon lamp as a source of the irradiation in order to simulate phototransformation processes which may occur in the environment. Furthermore, the photodegradation kinetics of three selected compounds were assessed in a reactor equipped with xenon lamp in river water samples. Five TPs of IBP, seven of KET, and five of FUR were identified; some of them are presented here for the first time. Accurate mass measurements and fragmentation pattern obtained during an LC-QTOF-MS analysis allowed for structure elucidation of TPs followed by the creation of transformation pathway of selected pharmaceuticals. Finally, different water samples (wastewater influent and effluent, river water, untreated and treated water) were analyzed in order to estimate the presence of parent and transformed compounds. Only KET was detected in untransformed form in considered samples. Most of the TPs of selected drugs were found at least once in all water samples. Although IBP and FUR were not present in water samples as parent compounds, their different TPs occur. A great potential of LC-QTOF-MS in the identification and structural elucidation of TPs in the environment, allowing the recognition of the fate of pharmaceuticals in the environment through the determination of transformation pathway, has been presented. Phototransformation of three selected pharmaceuticals Electronic supplementary materialThe online version of this article (doi:10.1007/s00216-014-7614-1) contains supplementary material, which is available to authorized users.

LC/MS DETERMINATION OF A SULFOLANE METABOLITE IN WETLAND VEGETATION EXPOSED TO GAS-CONDENSATE CONTAMINATED GROUND WATER

Groundwater containing the process chemicals sulfolane (tetrahydrothiophene 1,1-dioxide) and diisopropanolamine (DIPA) has contaminated a wetland in the vicinity of a sour-gas natural gas processing facility. Residues of the chemicals are found in wetland soil, water and vegetation. While it is known that DIPA undergoes transformation in wetlands plants, little is known regarding the degree of transformation of sulfolane. This is due in part to the lack of analytical methods suitable for the determination of transformation products of sulfolane in vegetation. Described is a new procedure, employing electrospray ionization with reverse-phase liquid chromatography mass spectrometry for the determination of the 3-hydroxysulfolane metabolite in plant tissue. The metabolite was determined using filtered water extracts of the vegetation, preconcentrated using solid-phase extraction with no further clean up or derivatization steps. Under positive ion electrospray conditions, there was preferential formation of a series of adducts with minimal (M+H)+ formation. The same was true for negative-ions, for which the molecular ion was not observed. However, the latter was more selective for crude extracts of vegetation. Quantification was performed using selected ion monitoring of the m/z 197.03 (M+61)− adduct, elucidated as the (M−1)(CN·(H2O)2)− negative-ion. Confirmations were based on comparison of the retention time and product ion scan of an authentic standard. Instrumental detection limits were attainable in the picogram range (50–100 pg injected). Successful application of the procedure is demonstrated for the determination of the metabolite in 22 samples, collected from a sour-gas contaminated wetland and a control site. For roots, shoots, berries, seeds, grasses, and leaves, the recovery was 117±5.6% r.s.d with a detection limit of 50 ng/g. In general, the technique was rugged (based on a study period of 18 months), and relatively fast (∼25 min per sample for a batch of 10 samples). For the study period, it appears that sulfolane is also transformed in the plants in a manner similar to DIPA, suggesting that degradation of both process chemicals occurs in wetland plants.