共查询到20条相似文献,搜索用时 15 毫秒
1.
Eduardo Gatica David Possetto Agustina Reynoso Jos Natera Sandra Miskoski Eduardo De Gernimo Mabel Bregliani Adriana Pajares Walter A. Massad 《Photochemistry and photobiology》2019,95(3):901-908
The proherbicide Isoxaflutole (IXF) hydrolyzes spontaneously to diketonitrile (DKN) a phytotoxic compound with herbicidal activity. In this work, the sensitized degradation of IXF using Riboflavin (Rf), a typical environmentally friendly sensitizer, Fenton and photo‐Fenton processes has been studied. The results indicate that only the photo‐Fenton process produces a significant degradation of the IXF. Photolysis experiments of IXF sensitized by Riboflavin is not a meaningful process, IXF quenches the Rf excited triplet (3Rf*) state with a quenching rate constant of 1.5 · 107 m ?1 s?1 and no reaction is observed with the species O2(1Δg) or generated from 3Rf*. The Fenton reaction produces no changes in the IXF concentration. While the photo‐Fenton process of the IXF, under typical conditions, it produces a degradation of 99% and a mineralization to CO2 and H2O of 88%. A rate constant value of 1.0 × 109 m ?1 s?1 was determined for the reaction between IXF and HO˙. The photo‐Fenton process degradation products were identified by UHPLC‐MS/MS analysis. 相似文献
2.
Liquid chromatographic method and micellar electrokinetic chromatographic method were optimized for determination of atrazine, desethylatrazine, desisopropylatrazine, hydroxyatrazine and their polar degradation products in solutions with humic acid without previous sample preparation step. Reversed-phase HPLC method was satisfactory in terms of repeatability and detection limits, which were ± 1.7–12.5% (RSD) and 0.1–0.5 mg L?1, respectively. However, the most polar products could not be separated from the front peak pertaining to humic acid. With MEKC, excellent separation of both chloro and hydroxy degradation products and parent compounds was achieved in a single analysis, and possible interferences of humic acid were successfully avoided by its retention at the anode. Drawbacks were detection limits, estimated to be 2–4 mg L?1, and RSD of the migration times was 20% compared to 0.5% with HPLC method. HPLC method was used to monitor degradation of atrazine and its first degradation products in the presence of humic acids, and MEKC was used for confirmation purposes. 相似文献
3.
Monitoring the enforcement of an EU-wide ban of nitrofuran antibiotics in the food production chain is a challenging task,
given the nature of nitrofuran compounds. The original and modified Fenton reactions are advanced oxidation processes that
can eliminate the toxicity of nitrofurans. 2-(5-Nitrofuryl)acrylic acid (I) was degraded as a model compound by the original Fenton reaction with ferrous sulphate, by Mohr’s salt at pH 3 and 7, and
finally by advanced Fenton process (AFP) (Fe0/H2O2/H2SO4). In addition, the growth inhibition of Escherichia coli, a G− bacterium, was tested both before and after AFP treatment. The results showed that a small degradation efficiency of this
treatment process led to the toxicity changes and that the toxicity of I after AFP treatment process decreased. It seems that the treatment of polluted water using the Fenton reaction and its modifications
would be a suitable method for degradation of nitrofuran derivatives in polluted water. 相似文献
4.
《Arabian Journal of Chemistry》2020,13(4):5084-5095
Present study deals with the treatment of coking wastewater (CWW) using Fenton oxidation process for the degradation of pollutants containing chemical oxygen demand (COD), phenol and cyanide. The experiments were performed in batch mode to study the effect of operating parameters like initial pH (pHi), temperature (T), oxidant H2O2 amount, catalyst mass loading (Cw) and treatment time (tR). The response surface methodology (RSM) gave optimum value of pH, H2O2, Cw and tR as 3, 0.3 M, 1.85 g/L (0.0266 M) and 1.52 h. At this optimum operating condition maximum 84.66% COD, 88.46% phenol and 79.34% cyanide reduction were achieved from initial value of COD (CODi) = 2810.0 mg/L, phenoli = 283.0 mg/L and cyanidei = 18.88 mg/L. Results reflect that Fenton oxidation is an effective process for the reduction of pollutants present in CWW. The CWW treated by Fenton oxidation having average value COD = 590.0 mg/L, phenol = 39.49 mg/L and cyanide = 5.2 mg/L was further treated by adsorption process as second stage treatment, and these values were reached to COD = 199.0 mg/L, phenol = 0.0 mg/L and cyanide = 2.36 mg/L. The response surface methodology (RSM) was used for the designing and optimization of the experiments. Analysis of variance (ANOVA) suggested the high regression coefficient R2 = 0.999 and 0.993 for COD and phenol removal respectively. The two stage treated CWW can be recycled and reused in same industry for various purpose. 相似文献
5.
Li L Abe Y Kanagawa K Shoji T Mashino T Mochizuki M Tanaka M Miyata N 《Analytica chimica acta》2007,599(2):315-319
Hydroxyl radical formation by Fenton reaction in the presence of an iron-chelating agent such as EDTA was traced by two different assay methods; an electron spin resonance (ESR) spin-trapping method with 5,5-dimethyl-1-pyrroline N-oxide (DMPO), and high Performance liquid chromatography (HPLC)-fluorescence detection with terephthalic acid (TPA), a fluorescent probe for hydroxyl radicals. From the ESR spin-trapping measurement, it was observed that EDTA seemed to suppress hydroxyl radical formation with the increase of its concentration. On the other hand, hydroxyl radical formation by Fenton reaction was not affected by EDTA monitored by HPLC assay. Similar inconsistent effects of other iron-chelating agents such as nitrylotriacetic acid (NTA), diethylenetriamine penta acetic acid (DTPA), oxalate and citrate were also observed. On the addition of EDTA solution to the reaction mixture 10 min after the Fenton reaction started, when hydroxyl radical formation should have almost ceased but the ESR signal of DMPO-OH radicals could be detected, it was observed that the DMPO-OH signal disappeared rapidly. With the simultaneous addition of Fe(II) solution and EDTA after the Fenton reaction ceased, the DMPO-OH signal disappeared more rapidly. The results indicated that these chelating agents should enhance the quenching of [DMPO-OH] radicals by Fe(II), but they did not suppress Fenton reaction by forming chelates with iron ions. 相似文献
6.
可见光/Fenton光催化降解有机染料 总被引:35,自引:0,他引:35
采用Fenton试剂(Fe3+/H2O2)在可见光条件下(λ>450nm)光催化降解目标染料化合物罗丹明B(RhodamineB,RhB).在pH<3.0体系中用可见光照射,能使RhB染料在光敏化作用下有效降解,反应160min后矿化率达到71.8%.采用ESR和溴甲酚绿(Bromocresolgreen,BCG)法跟踪测定活性氧化物种,通过对RhB降解过程的紫外-可见光谱、红外光谱分析及总有机碳量(TOC)跟踪测定,结果表明,Fe3+/H2O2/RhB体系在可见光照射下主要的活性氧化物种为羟基自由基,能有效地降解RhB. 相似文献
7.
Summary HPTLC densitometry and HPLC are considered for the simultaneous determination of the degradation products of piroxicam (2-aminopyridine,
DP-I and DP-II). The substances were separated on silica gel with fluorescence indicator in ethylacetate — toluene — diethylamine
(10∶10∶5) and toluene — absolute ethanol — glacial acetic acid (8∶1.2∶0.5) systems. The measuring absorbance (detection of
reflectance) of the separated substances was carried out “in situ” at 296 nm using 4-level calibration (external standard,
nonlinear regresson function) in the concentration range 600–1200 ng 2-aminopyridine/spot and 300–600 ng DP-I and DP-II/spot.
The HPLC method was carried out using RP-8 stationary phase and methanol + phosphate-citrate buffer, pH 3 mobile phase with
addition of sodium pentanesulfonate (40+60, v/v). 2-aminopyridine wass detected at 300 nm, DP-I at 280 nm and DP-II at 248
nm. The concentration range for 2-aminopyridine is 2–40 μg/ml, for DP-I and DP-II 2–20 μg/ml (for an injection volume of 10
μl). The results were evaluated by linear regression analysis. 相似文献
8.
Carla Sirtori Ana Agüera Irene Carra José A. Sanchéz Pérez 《Analytical and bioanalytical chemistry》2014,406(22):5323-5337
This work enabled the identification of major transformation products (TPs) of thiabendazole (TBZ) during the Fenton process. TBZ is a benzimidazole fungicide widely used around the world to prevent and/or treat a wide range of fruit and vegetable pathogens. The degradation of the parent molecule and the identification of the main TPs were carried out in demineralized water. The TPs were monitored and identified by liquid chromatography-quadrupole time-of-flight mass spectrometry (LC-QTOF-MS/MS). Up to 12 TPs were tentatively identified. Most of them were eliminated after 15 min of treatment time and originated from numerous hydroxylations undergone by the aromatic ring during the initial stages of the process. 相似文献
9.
Abstract
Oil-in-water emulsions can be stabilized by solid particles. These so-called Pickering emulsions are regularly used in many technological applications. Here we describe the efficiency of sol–gel-synthesized anatase nanoparticles with a diameter of 6 nm in stabilizing emulsions. Key parameters were the surface charge of the particles—depending on pH and salt concentration—and their contact angle—depending on the surface groups and the polarity of the oil phase. The effect of these properties on the stability of the emulsions was investigated. The sol–gel nanoparticles were most efficient in stabilizing emulsions at pH 3 (depending on the salt and particle concentration). Highly apolar oil phases (cyclohexane, n-hexane) were required to obtain stable emulsions with the investigated system and addition of salt or hydrophobic coupling molecules in the oil phase, such as long alkyl chain containing phosphonates, increased the stability of the emulsions. 相似文献10.
《Radiation Physics and Chemistry》2008,77(6):768-774
Removal of priority pollutant fluoranthene in methanol by gamma-irradiation under varied conditions has been optimized. The influence of applied dose and dose rate on the degradation of fluoranthene under nitrogen has been investigated. The preliminary radiolytic degradation efficiency has been monitored by spectrophotometry. HPLC and GC–MS have been used to study the nature of degradation pattern. It is found that four main degradation products are formed and detected by HPLC. Different reversed phase columns have been used for the separation of degraded products under optimum chromatographic conditions. For 2 kGy dose ⩾80% fluoranthene has been degraded at dose rate 200 Gy/h. However, a dose of 370 Gy/h was more effective and it produces for less degradation products. Radiolytic degraded fluoranthene was also analyzed to detect various degradation products using GC–MS. It was proposed that major products were hydrocarbons and methoxy group containing organic compounds after comparing their mass spectra with the installed NIST mass spectral library. 相似文献
11.
Summary An isocratic ion suppression reversed phase method is utilized for the qualitative and quantitative determination of L-ascorbic
acid in fresh fruit juices — complex sample matrices. The selectivity of the method, when a macroreticular poly(styrene-divinylbenzene)
reversed phase adsorbent is used, is sufficient to resolve the isomers L-ascorbic acid and D-erythorbic acid (isoascorbic
acid) to baseline in under 8 minutes. L-Ascorbic acid solution stability is monitored using the same analytical conditions
with the degradation products sufficiently well resolved not to interfere in the quantification of L-ascorbic acid. By the
use of commercial materials and the preparation of the proposed products of the oxidative degradation of L-ascorbic acid the
degradation sequence and identification of the products in an aged L-ascorbic acid solution is accomplished. 相似文献
12.
Consuelo Cháfer-Pericás Ángel Maquieira Rosa Puchades Javier Miralles Amelia Moreno 《Analytical and bioanalytical chemistry》2010,396(2):911-921
An indirect competitive enzyme-linked immunosorbent assay (ELISA) was developed in plate to detect three sulfonamide residues
(sulfamerazine (SMR), sulfadimetoxine (SDM), and sulfadiazine (SDZ)) in gilthead sea bream (Sparus aurata) samples. Different extraction methodologies—using methanol/water 1:1 (v/v) + ethylene diamine tetraacetic acid (EDTA) 0.5% (m/v), acetonitrile, phosphate-buffered saline (PBS) 10 mmol L−1 pH 7 and acetate buffer 100 mmol L−1 pH 5—and cleanup steps, based on solid-phase extraction (C18, SCX, Si) or liquid extraction with hexane, were assayed. As optimum, a fast and simple method using acetonitrile was selected
to extract the sulfonamide residues from the edible muscle of fish. Due to matrix effects, a standard addition calibration
curve in fish extract is necessary for quantification purposes. Sulfonamide-free samples were spiked at different concentration
levels (between 30 and 90 ng g−1, 5–15 ng mL−1 in plate) and average recoveries (n = 8), ranging from 71% to 95%, 65% to 79%, and 72% to 95%, were obtained for SMR, SDM, and SDZ, respectively. The assay detection
limits for these antibiotics were lower than 100 μg kg−1 (maximum residue level established by the European Union). The accuracy was evaluated by spiking blank fish extracts at different
concentrations (10–40 ng mL−1, 5–20 ng mL−1 in plate), and the relative errors ranged between ±20%. Finally, in order to confirm the utility of the developed ELISA as
a screening methodology, fish samples from different supermarkets were analyzed, and results were compared with those obtained
by a validated high-performance liquid chromatography (HPLC) method. The correlation between the results obtained by both
ELISA and HPLC methods is satisfactory.
相似文献
13.
Martin Egginger Siegfried Bauer Reinhard Schw?diauer Helmut Neugebauer Niyazi Serdar Sariciftci 《Monatshefte für Chemie / Chemical Monthly》2009,95(1):735-750
Abstract
Research into organic field effect transistors (OFETs) has made significant advances—both scientifically and technologically—during the last decade, and the first products will soon enter the market. Printed electronic circuits using organic resistors, diodes and transistors may become cheap alternatives to silicon-based systems, especially in large-area applications. A key parameter for device operation, besides long term stability, is the reproducibility of the current–voltage behavior, which may be affected by hysteresis phenomena. Hysteresis effects are often observed in organic transistors during sweeps of the gate voltage (V GS). This hysteresis can originate in various ways, but comparative scientific investigations are rare and a comprehensive picture of “hysteresis phenomena” in OFETs is still missing. This review provides an overview of the physical effects that cause hysteresis and discusses the importance of such effects in OFETs in a comparative manner. 相似文献14.
R. Curini A. Gentili S. Marchese D. Perret L. Arone A. Monteleone 《Chromatographia》2001,53(5-6):244-250
Summary The presence of 16 of the most widely used pesticides in southern Italy (plus atrazine, the use of which is currently restricted
in Europe) has been monitored in ten surface waters of the Calabria Region. The analytes were extracted from water by off-line
solid-phase extraction with a Carbograph cartridge. Base-neutral, and acid pesticides were then isolated by differential elution.
Analyte fractionation and quantification were performed by liquid chromatography (HPLC) with UV detection. Recoveries of analytes
from 0.5 L river water (200 ngL−1 spike level) were ≥84%. Confirmatory analysis was performed by HPLC coupled with ion-spray mass spectrometry (LC-ESI-MS). 相似文献
15.
Letícia Flores da Silva Martins Pedro Eduardo Froehlich Ana Maria Bergold 《Chromatographia》2009,69(Z2):109-113
A sensitive and rapid liquid chromatographic method was successfully developed and validated for the determination of sibutramine
hydrochloride in bulk and capsules. Sibutramine in the presence of its degradation products was analyzed using UV detection
at 225 nm. Chromatography was performed on a reversed-phase C8 (150 × 4.0 mm I.D., 5 μm) analytical column under isocratic conditions. The mobile phase was composed of acetonitrile:water
(aqueous phase containing 0.3% triethylamine and pH adjusted to 7.0) (75:25, v/v) at a flow-rate of 1.1 mL min−1. No chromatographic interference was found during the analysis. Light was the stress condition which most contributed to
sibutramine degradation. The method showed a linear response (r > 0.999) from 30 to 90 μg mL−1. The mean recovery for capsules was 101.2%. Inter-day assays showed relative standard deviations of 0.42 and 1.62% for bulk
and capsules, respectively. The developed method is able to separate sibutramine from its major degradation products and it
may be used in the quality control of this active pharmaceutical ingredient in both bulk and capsules. 相似文献
16.
Dumitru Condrat Cristina Mosoarca Alina D. Zamfir Florin Cri?an Maria R. Szabo Alfa X. Lupea 《Central European Journal of Chemistry》2010,8(3):530-535
This study presents the results obtained from qualitative and quantitative analysis of gallic acid from hydro-alcoholic extracts
(methanol, ethanol) of plants from Plantae regnum. Plant qualitative analysis was performed using a novel mass spectrometric (MS) method based on fully automated chip-nanoelectrospray
ionization (nanoESI) high capacity ion trap (HCT) while quantitative analysis was carried out by high performance liquid chromatography
(HPLC). These methods were applied to Alchemilla vulgaris — common lady’s-mantle (aerial part), Allium ursinum — bear’s garlic (leaves), Acorus calamus — common sweet flag (roots), Solidago virga-aurea — goldenrod (aerial part). Obtained results indicated that methanol extracts (96%, 80%) have a gallic acid content ranging
between 0.0011–0.0576 mg mL−1 extract while the ethanol extracts (96%, 60%) exhibit a gallic acid concentration that varies between 0.0010–0.0182 mg mL−1 extract.
相似文献
17.
Gisele B. Tonietto José M. Godoy Ana Cristina Oliveira Marcia V. de Souza 《Analytical and bioanalytical chemistry》2010,397(5):1755-1761
High-performance liquid chromatography (HPLC) coupled to an ICP-MS with an octapole reaction system (ORS) has been used to
carry out quantitative speciation of selenium (Se) and arsenic (As) in the stream waters of a refining process. The argon
dimers interfering with the 78Se and 80Se isotopes were suppressed by pressurizing the octapole chamber with 3.1 mL min−1 H2 and 0.5 mL min−1 He. Four arsenic species arsenite—As(III), arsenate (As(V)), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA)—and
three inorganic Se species—selenite Se(IV), selenate Se(VI), and selenocyanate (SeCN−)—were separated in a single run by ion chromatography (IC) using gradient elution with 100 mmol L−1 NH4NO3, pH 8.5, adjusted by addition of NH3, as eluent. Repeatabilities of peak position and of peak area evaluation were better than 1% and about 3%, respectively.
Detection limits (as 3σ of the baseline noise) were 81, 56, and 75 ng L−1 for Se(IV), Se(VI), and SeCN−, respectively, and 22, 19, 25, and 16 ng L−1 for As(III), As(V), MMA, and DMA, respectively. Calibration curve R
2 values ranged between 0.996 and 0.999 for the arsenic and selenium species. Column recovery for ion chromatography was calculated
to be 97 ± 6% for combined arsenic species and 98 ± 3% for combined selenium species. Because certified reference materials
for As and Se speciation studies are still not commercially available, in order to check accuracy and precision the method
was applied to certified reference materials, BCR 714, BCR 1714, and BCR 715 and to two different refinery samples—inlet and
outlet wastewater. The method was successfully used to study the quantitative speciation of selenium and arsenic in petroleum
refinery wastewaters. 相似文献
18.
Manoelly Oliveira Rocha Gabriele Bordignon Primieri Nathalie Ribeiro Wingert Jacqueline Arguello Da Silva Martin Steppe 《Electrophoresis》2022,43(15):1617-1625
The incidence of thrombotic complications in SARS-CoV-2 infections has become a global concern; thus, anticoagulants are an integral part of the treatment. Edoxaban (EDX) is an oral anticoagulant suitable for pharmacologic thromboprophylaxis. Herein, two novel analytical methods for EDX determination in tablets are developed and validated using capillary zone electrophoresis (CZE) and high-performance liquid chromatography (HPLC). Operating conditions such as the electrolyte's concentration and pH value, injection time, volume, and the capillary temperature, were optimized. The methods were successfully validated by establishing the linearity, intra- and inter-day precisions (relative standard deviation [%]), accuracy, and robustness. Adequate separation of excipients and degradation products of EDX generated by stress degradation conditions demonstrated the stability-indicating capability of the methods. The analytical procedures were linear in the range of 25–125 µg/ml (r > 0.999), with the limits of detection and quantification of 3.26 and 10.87 µg/ml for CZE and 0.740 and 2.78 µg/ml for HPLC. Although both methodologies are suitable for determining EDX in tablets, CZE provides a greener alternative due to low-cost analysis using less organic solvents and minimizing waste generation. 相似文献
19.
《印度化学会志》2021,98(9):100115
In this paper the oxidative degradation process of methyl vanillin wastewater was studied by the subcritical water oxidation (HCWO) technology. A subcritical Fenton oxidation (HCFO) system formed while Fe2+ was added as a catalyst. The oxidation degradation kinetics of methyl vanillin wastewater was also studied. The results showed that the suitable process conditions for degradation of methyl vanillin wastewater by HCWO were as follows: temperature of 340 °C, pressure of 24 MPa, oxidant multiple of 1.5, residence time of 217.3 s (flow rate of 2.0 mL min-1). For methyl vanillin wastewater, the HCFO system has no obvious advantages compared to the HCWO system. The activation energy (Ea) of HCWO oxidized methyl vanillin wastewater reaction was 32.6 kJ mol-1, and the pre-exponential factor A was 5.64 s-1. 相似文献
20.
Mohammed A. Abounassif Mohammed M. Hefnawy Gamal A. E. Mostafa 《Monatshefte für Chemie / Chemical Monthly》2012,73(Z1):365-371