Sulfamethizole Research Articles

Regulating the Co 3d center of Co3O4 by Co3O4/g-C3N4 to enhance electronic activity for sulfamethizole effectively degaradtion by permonosulfate activation

The Permonosulfate (PMS) activation via Co based catalysts have been recognized as the most effective PMS activation method. However, regulating the Co-3d band center of Co based catalysts to enhance PMS activation is still a challenge. Since g-C3N4 is often a good carrier for transition metals and their oxides, in this work, the Co3O4/g-C3N4 was developed by a simple way to modulate the Co-3d band center of Co3O4 and was used to sulfamethizole (STZ) degradation. Also, some characterizations demonstrated the Co3O4/g-C3N4 has been successfully prepared such as Transmission electron microscope (TEM), X-ray Diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). It also showed an effective removal efficiency for STZ by PMS activation (k1 = 0.77 min−1). The reactive oxygen species (ROS) quenching experiments verified the main ROS are 1O2 and SO4•−. The DFT results indicated that the Co-3d of Co3O4 band center (from −1.78 eV to −1.41 eV) was successfully modulated, further improving the electronic utilization efficiency and electronic activity, thus effective PMS activation was obtained. This work not only provided a potential way to antibiotics removal in water, but also offered a mechanism analysis of PMS activation by Co-based catalysts in depth.

Comparing the photodegradation of typical antibiotics in ice and in water: Degradation kinetics, mechanisms, and effects of dissolved substances

New antibiotic contaminants have been detected in both surface waters and natural ice across cold regions. However, few studies have revealed distinctions between their ice and aqueous photochemistry. In this study, the photodegradation and effects of the main dissolved substances on the photolytic kinetics were investigated for sulfonamides (SAs) and fluoroquinolones (FQs) in ice/water under simulated sunlight. The results showed that the photolysis of sulfamethizole (SMT), sulfachloropyridazine (SCP), enrofloxacin (ENR) and difloxacin (DIF) in ice/water followed the pseudo-first-order kinetics with their quantum yields ranging from 4.93 × 10−3 to 11.15 × 10−2. The individual antibiotics experienced disparate photodegradation rates in ice and in water. This divergence was attributed to the concentration-enhancing effect and the solvent cage effect that occurred in the freezing process. Moreover, the main constituents (Cl−, HASS, NO3− and Fe(III)) exhibited varying degrees of promotion or inhibition on the photodegradation of SAs and FQs in the two phases (p < 0.05), and these effects were dependent on the individual antibiotics and the matrix. Extrapolation of the laboratory data to the field conditions provided a reasonable estimate of environmental photolytic half-lives (t1/2,E) during midsummer and midwinter in cold regions. The estimated t1/2,E values ranged from 0.02 h for ENR to 14 h for SCP, which depended on the reaction phases, latitudes and seasons. These results revealed the similarities and differences between the ice and aqueous photochemistry of antibiotics, which is important for the accurate assessment of the fate and risk of these new pollutants in cold environments.

Improved tolerance capacity and expression of degradation genes drive efficient removal of sulfamethizole by Chlorella pyrenoidosa

In this study, the tolerance capacities and expression of key degradation genes of a microalgal species, Chlorella pyrenoidosa prior exposure to sulfamethizole (SFT) were investigated. The results showed that acclimated microalgae had higher tolerance capacities comparing to the wild type since the half-maximum effective concentrations at 96 h increased from 31.27 mg L−1 to 51.27 mg L−1. Meanwhile, the removal of SFT was enhanced by 45.5% after acclimation, which was mainly induced by biodegradation. Bioaccumulated SFT was 17.65 and 24.61 µg g−1 in wild type and acclimated species. Gradually increased content of reactive oxygen species might act as the secondary massager to monitor the cellular metabolic pathways including synthesis of energy sources and energy metabolism. Key biodegradation genes were identified with upregulated log 2-fold change of > 6. These genes may help to biodegrade SFT in acclimation process. This study tried to unravel the underlying mechanism of acclimation process in microalgal degradation of persistent sulfonamide antibiotics, which might be useful in increasing the engineering feasibility in treatment of antibiotics’ wastewater.

Investigating sulfonamides - Human serum albumin interactions: A comprehensive approach using multi-spectroscopy, DFT calculations, and molecular docking

The environmental and health risks associated with sulfonamide antibiotics (SAs) are receiving increasing attention. Through multi-spectroscopy, density functional theory (DFT), and molecular docking, this study investigated the interaction features and mechanisms between six representative SAs and human serum albumin (HSA).Multi-spectroscopy analysis showed that the six SAs had significant binding capabilities with HSA. The order of binding constants at 298 K was as follows: sulfadoxine (SDX): 7.18 × 105 L mol−1 > sulfamethizole (SMT): 6.28 × 105 L mol−1 > sulfamerazine (SMR): 2.70 × 104 L mol−1 > sulfamonomethoxine (SMM): 2.54 × 104 L mol−1 > sulfamethazine (SMZ): 3.06 × 104 L mol−1 > sulfadimethoxine (SDM): 2.50 × 104 L mol−1. During the molecular docking process of the six SAs with HSA, the binding affinity range is from −7.4 kcal mol−1 to −8.6 kcal mol−1. Notably, the docking result of HSA-SDX reached the maximum of −8.6 kcal mol−1, indicating that SDX may possess the highest binding capacity to HSA. HSA-SDX binding, identified as a static quenching and exothermic process, is primarily driven by hydrogen bonds (H bonds) or van der Waals (vdW) interactions. The quenching processes of SMR/SMZ/SMM/SDX/SMT to HSA are a combination of dynamic and static quenching, indicating an endothermic reaction. Hydrophobic interactions are primarily accountable for SMR/SMZ/SMM/SDX/SMT and HSA binding. Competition binding results revealed that the primary HSA-SAs binding sites are in the subdomain IB of the HAS structure, consistent with the results of molecule docking.The correlation analysis based on DFT calculations revealed an inherent relationship between the structural chemical features of SAs and the binding performance of HSA-SAs. The dual descriptor (DD) and the electrophilic Fukui function were found to have a significant relationship (0.71 and −0.71, respectively) with the binding constants of HSA-SAs, predicting the binding performance of SAs and HSA. These insights have substantial scientific value for evaluating the environmental risks of SAs as well as understanding their impact on biological life activities.

Photocatalytic degradation of antibiotic sulfamethizole by visible light activated perovskite LaZnO3

In this work, the perovskite LaZnO3 was synthesized via sol-gel method and applied for photocatalytic treatment of sulfamethizole (SMZ) antibiotics under visible light activation. SMZ was almost completely degraded (99.2% ± 0.3%) within 4 hr by photocatalyst LaZnO3 at the optimal dosage of 1.1 g/L, with a mineralization proportion of 58.7% ± 0.4%. The efficient performance of LaZnO3 can be attributed to its wide-range light absorption and the appropriate energy band edge levels, which facilitate the formation of active agents such as ·O2−, h+, and ·OH. The integration of RP-HPLC/Q-TOF-MS and DFT-based computational techniques revealed three degradation pathways of SMZ, which were initiated by the deamination reaction at the aniline ring, the breakdown of the sulfonamide moieties, and a process known as Smile-type rearrangement and SO2 intrusion. Corresponding toxicity of SMZ and the intermediates were analyzed by quantitative structure activity relationship (QSAR), indicating the effectiveness of LaZnO3-based photocatalysis in preventing secondary pollution of the intermediates to the ecosystem during the degradation process. The visible-light-activated photocatalyst LaZnO3 exhibited efficient performance in the occurrence of inorganic anions and maintained high durability across multiple recycling tests, making it a promising candidate for practical antibiotic treatment.

The removal of veterinary antibiotics in the high-rate anaerobic bioreactor: continuous and batch studies.

Veterinary antibiotics in swine wastewater has drawn great public attention. The removal processes of sulfamethizole (SMZ), enrofloxacin (ENR) and chlortetracycline (CTC) were investigated in the high-rate anaerobic process. The continuous experiments demonstrated that in 3 L working volume and with the organic loading rate 5 kg/(m3·d) rised to 20 kg/(m3·d), the average removal efficiencies of the high-rate anaerobic bioreactor for SMZ, ENR and CTC were 0, 54 and 100%, respectively. By using fixed-bed adsorption models, the saturation time of SMZ, ENR and CTC were 4 hydraulic retention time (HRT) (24 h), 8 HRT (48 h) and 372 HRT (2,232 h). In the batch experiments, the adsorption and biodegradation characteristics of anaerobic granular sludge were determined. In the high-rate anaerobic bioreactor, SMZ removal process mainly relied on the adsorption but it was very weak; ENR removal process was based on the adsorption and biodegradation; CTC removal process was based to a large extent on the adsorption because of the big capacity of AnGS. These results were helpful to create a rational basis for designing more suitable treatment systems as feasible barriers to the release of antibiotics into the environment.

Electrocatalytic degradation of sulfamethylthiadiazole by GAC@Ni/Fe three-dimensional particle electrode

In this work, GAC@Ni/Fe particle electrodes were prepared and employed for the degradation of sulfamethylthiadiazole (SMT) by three-dimensional electrocatalytic technology. The effects of particle electrode bi-metal loading ratio, cell voltage, particle electrode dosage, electrode plate spacing, and SMT initial concentration on SMT removal were studied. In addition, GAC@Ni/Fe particle electrode was analyzed by the scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffractometer (XRD), X-ray photoelectron spectrometer (XPS), and Fourier transform infrared spectrometer (FTIR) to characterize which indicated that a significant amount of iron-nickel oxide was formed on the surface of GAC@Ni/Fe particle electrode. The results indicated that when the nickel-iron loading ratio is 1:1, the SMT removal effect is the best, and the removal rate can reach 90.89% within 30min. Compared with the granular activated carbon without bimetal, the removal efficiency is increased by 37.58%. The degradation of SMT in the GAC@Ni/Fe particle three-dimensional electrode reactor is the joint result of both direct oxidation and indirect oxidation. The contribution rates of direct oxidation of anode and particle electrode and indirect oxidation of ·OH in the degradation are 32%, 27%, and 41%, respectively. Based on the intermediate detected by ultra-high liquid chromatography and the calculation of bond energy of SMT molecule by Gauss software, the degradation pathway of SMT in the GAC@Ni/Fe three-dimensional electrode reactor is proposed. This research provides a green, healthy, and effective method for removing sulfonamide micro-polluted wastewater.

Experimental and Theoretical Screening for Green Solvents Improving Sulfamethizole Solubility.

Solubility enhancement of poorly soluble active pharmaceutical ingredients is of crucial importance for drug development and processing. Extensive experimental screening is limited due to the vast number of potential solvent combinations. Hence, theoretical models can offer valuable hints for guiding experiments aimed at providing solubility data. In this paper, we explore the possibility of applying quantum-chemistry-derived molecular descriptors, adequate for development of an ensemble of neural networks model (ENNM), for solubility computations of sulfamethizole (SMT) in neat and aqueous binary solvent mixtures. The machine learning procedure utilized information encoded in σ-potential profiles computed using the COSMO-RS approach. The resulting nonlinear model is accurate in backcomputing SMT solubility and allowed for extensive screening of green solvents. Since the experimental characteristics of SMT solubility are limited, the data pool was extended by new solubility measurements in water, five neat organic solvents (acetonitrile, N,N-dimethylformamide, dimethyl sulfoxide, 1,4-dioxane, and methanol), and their aqueous binary mixtures at 298.15, 303.15, 308.15, and 313.15 K. Experimentally determined order of decreasing SMT solubility in neat solvents is the following: N,N-dimethylformamide > dimethyl sulfoxide > methanol > acetonitrile > 1,4dioxane >> water, in all studied temperatures. Similar trends are observed for aqueous binary mixtures. Since N,N-dimethylformamide is not considered as a green solvent, the more acceptable replacers were searched for using the developed model. This step led to the conclusion that 4-formylmorpholine is a real alternative to N,N-dimethylformamide, fulfilling all requirements of both high dissolution potential and environmental friendliness.

Adsorption and Release of Sulfamethizole from Mesoporous Silica Nanoparticles Functionalised with Triethylenetetramine.

Mesoporous silica nanoparticles (MSN) were synthesised and functionalised with triethylenetetramine (MSN-TETA). The samples were fully characterised (transmission electron microscopy, small angle X-ray scattering, Fourier transform infrared spectroscopy, thermogravimetric analysis, zeta potential and nitrogen adsorption/desorption isotherms) and used as carriers for the adsorption of the antimicrobial drug sulphamethizole (SMZ). SMZ loading, quantified by UV–Vis spectroscopy, was higher on MSN-TETA (345.8 mg g−1) compared with bare MSN (215.4 mg g−1) even in the presence of a lower surface area (671 vs. 942 m2 g−1). The kinetics of SMZ adsorption on MSN and MSN-TETA followed a pseudo-second-order model. The adsorption isotherm is described better by a Langmuir model rather than a Temkin or Freundlich model. Release kinetics showed a burst release of SMZ from bare MSN samples (k1 = 136 h−1) in contrast to a slower release found with MSN-TETA (k1 = 3.04 h−1), suggesting attractive intermolecular interactions slow down SMZ release from MSN-TETA. In summary, the MSN surface area did not influence SMZ adsorption and release. On the contrary, the design of an effective drug delivery system must consider the intermolecular interactions between the adsorbent and the adsorbate.

Nitrite-mediated photodegradation of sulfonamides and formation of nitrated products

In this study, we systematically investigated the indirect photolysis of five SAs, i.e., sulfamethazine (SMZ), sulfamethoxazole (SMX), sulfathiazole (STZ), sulfapyridine (SPD), and sulfamethizole (SMT), under UV-A irradiation (365 nm) and mediated by nitrite (NO2‾) at environmentally relevant concentrations (0.005–0.1 mM). The SAs that are resistant to direct photolysis can be effectively removed in UV/NO2‾ system. SAs with a six-membered heterocyclic ring (i.e., SMZ and SPD) were degraded more quickly than those with a five-membered heterocyclic ring (i.e., SMX, STZ and SMT). The pseudo-first-order rate constants (k) at nitrite concentration of 0.1 mM followed the order of kSPD (0.0265 min−1) > kSMZ (0.0245 min−1) > kSMX (0.0184 min−1) > kSTZ (0.0176 min−1) > kSMT (0.0154 min−1). A kinetic model was developed and the contributions of direct UV photolysis, OH, and RNS to SAs degradation in UV/NO2‾ system were calculated. At NO2‾ concentration of 0.1 mM, the contributions of OH and RNS for SAs removal were 29.17–46.53% and 52.33–63.28%, respectively. Main transformation pathways including hydroxylation and nitration were proposed, based on liquid chromatography mass spectrometry analysis of the degradation products and density functional theory calculation. However, Smile-type rearrangement which generated a SO2-extrusion product was only observed in the degradation of SAs with a six-membered ring, which explains their higher degradation rate than those with a five-membered ring. The presence of natural organic matter (NOM) decreased the formation of nitrated products. Overall, these results will be helpful to understand the fate and the potential ecological risks of SAs in sunlit aquatic environments.

Preferred protonation site of a series of sulfa drugs in the gas phase revealed by IR spectroscopy

Sulfa drugs are an important class of pharmaceuticals in the treatment of bacterial infections. The amido/imido tautomerism of these molecules in their neutral form has been widely discussed in the literature. Here, we study the protonation preferences of sulfa drugs upon electrospray ionization (ESI) using IR action spectroscopy of the ionized gas-phase molecules in a mass spectrometer. Our set of molecules includes sulfanilamide (SA), the progenitor of the family of sulfa drugs, and the actual, sulfonamide nitrogen substituted, sulfa drugs sulfamethoxazole (SMX), sulfisoxazole (SIX), sulfamethizole (SMZ), sulfathiazole (STZ), sulfapyridine (SP) and sulfaguanidine (SG). IR multiple photon dissociation (IRMPD) spectra were recorded for the protonated sulfa drugs using a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR-MS) and an optical parametric oscillator/amplifier (OPO/OPA) as well as the FELIX free electron laser (FEL) as IR sources. The OPO provides tunable IR radiation in the NH stretch region (3100–3700 cm^{-1}), while the FEL covers the fingerprint region (520–1750 cm^{-1}). Comparison of experimental IR spectra with spectra predicted using density functional theory allowed us to determine the gas-phase protonation site. For SA, the sulfonamide NH_2 group was identified as the protonation site, which contrasts the situation in solution, where the anilinic NH_2 group is protonated. For the derivative sulfa drugs, the favored protonation site is the nitrogen atom included in the heterocycle, except for SG, where protonation occurs at the sulfonamide nitrogen atom. The theoretical investigations show that the identified protonation isomers correspond to the lowest-energy gas-phase structures.

Removal of sulfamethizole from aqueous solution using advanced oxidation processes: effects of pH and salinity.

This study investigates the removal of sulfamethizole (SFZ) in ozone (O3), O3/Na2S2O8 (sodium persulfate), UV/Na2S2O8, UV/O3, and UV/O3/Na2S2O8 systems. The effects of pH and salinity on SFZ mineralization were evaluated. The mineralization of SFZ followed pseudo-first-order kinetics. At pH 5, the rate constants of SFZ mineralization in O3, O3/Na2S2O8, UV/Na2S2O8, UV/O3, and UV/O3/Na2S2O8 systems were 0.576, 0.924, 0.702, 1.26, and 5.21 h-1, respectively. The SFZ mineralization rate followed the order pH 5 > pH 7 > pH 9 in all tested advanced oxidation processes. Salinity increased the rate of SFZ mineralization in O3 and O3/Na2S2O8 systems and decelerated it in UV/Na2S2O8, UV/O3, and UV/O3/Na2S2O8 systems. UV/O3/Na2S2O8 was the best system for mineralizing SFZ, and sulfate radicals were the predominant species in UV/O3/Na2S2O8.

Key roles of electron cloud density and configuration in the adsorption of sulfonamide antibiotics on carbonaceous materials: Molecular dynamics and quantum chemical investigations

Electron transfer often drives the adsorption, but its role is difficult to determine by traditional experimental methods. In this work, two typical carbonaceous materials, graphene (GPE) and graphyne (GPY) were selected as adsorbents, and three sulfonamide antibiotics, sulfamethazine (SMT), sulfamethoxazole (SMX), and sulfamethizole (SMZ) were used as the model adsorbates. Molecular dynamics simulations and quantum chemical calculations were combined to explore the adsorption behavior and mechanisms. Molecular dynamics results showed that the antibiotic molecules were most likely to be adsorbed at a distance of 4–5 Å from the GPE and GPY surfaces. Subsequently, the energies and electronic information were analyzed based on quantum chemical calculations. The N-atom in the pyrimidine ring of SMT exhibited a stronger electron-donating ability than the O- and S-atoms in the heterocycles of SMX and SMZ, thereby enhancing its interaction with GPE and promoting its adsorption. GPE has a stronger π electron system and conjugation effect compared with GPY, and its triangular electron cloud configuration gives it a stronger adsorption ability. The electron cloud density and configuration played key roles in the adsorption. These results provide fundamental theoretical support for the structural design and optimization of carbonaceous materials and the efficient removal of sulfonamide antibiotics.

Sulfamethizole-imprinted polymer on screen-printed electrodes: Towards the design of a portable environmental sensor

As the demand for portable, selective yet sensitive environmental pollutants monitoring devices increases, electrochemical sensors specifically screen-printed electrodes (SPEs) integrated with molecularly imprinted polymer layers are gaining unprecedented attention. The work reported herein demonstrates a successful adaptation of an antibiotic imprinted polymer from one platform to another of different sensing principles, without compromising its performance. Specifically, sulfamethizole-MIP (SMZ-MIP) previously optimized on a surface acoustic wave (SAW) platform is redesigned on SPE with necessary upgrade to achieve a portable and highly-performing cost-effective electrochemical sensor for detecting sulfamethizole (SMZ) in water. Sensor performance, as analysed by differential pulse voltammetry (DPV) electrochemical technique indicates rapid response, good sensitivity as represented by an LOD of 0.9 nM, and LOQ of 3 nM; excellent selectivity, as well as concentration dependent responses both in buffer and tap water samples. This study indicates a significant step towards achieving the desired commercially viable small molecule detection platform that combines important peculiarity of low cost, ease of operation, portability and on-site utilization in environmental water.

Net-like mesoporous carbon nanocomposites for magnetic solid-phase extraction of sulfonamides prior to their quantitation by UPLC-HRMS.

A net-like mesoporous carbon nanocomposite (MCN) was hydrothermally prepared by using filter paper as the raw material. The MCN contains magnetic nanoparticles of type Fe3O4 which result from the addition of Fe(NO3)3·9H2O during synthesis. The MCN was characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, Raman spectra, Brunauer-Emmett-Teller methods and vibrating sample magnetometry. The MCN is shown to be a viable material for magnetic solid-phase extraction of trace sulfonamides (SAs) including sulfadiazine, sulfapyridine, sulfamerazine, sulfamethazine, sulfamethizole, sulfamethoxypridazine, sulfachloropyridazine and sulfadimethoxine. Following desorption with acetone containing 0.5% ammonia, the SAs were quantified by UPLCwith high-resolution mass spectrometric detection. With sulfamethazine as an example, the adsorption equilibrium configurations and the major interaction mechanism between SAs and the MCN were calculated by using density functional theory. Under the optimal conditions, the calibration plots are linear in the 0.05-10ng·mL-1 SA concentration ranges. The limits of detection are between 7.2 and 13.6ng·L-1. The recoveries from spiked samples ranged from 79 to 107%, with relative standard deviations of <9.9%. Graphical abstractSchematic representation of nanocomposite preparation, adsorption mechanism of sulfonamide and magnetic solid-phase extraction (MSPE) for sulfadiazine (SDZ), sulfapyridine (SPD), sulfamerazine (SMR), sulfamethazine (SMZ), sulfamethizole (SMT), sulfamethoxypridazine (SMP), sulfachloropyridazine (SCP) and sulfadimethoxine (SDMX).Quantificationwas accomplished by UPLC with high-resolution mass spectrometric detection.

Structural Features of Sulfamethizole and Its Cocrystals: Beauty Within

Sulfamethizole (SMZ) is an antibiotic drug with good solubility but short in vivo half-life. Thus, reducing the dissolution rate is expected to improve bioavailability and therapeutic activity thro...

Occurrence and Risk Assessment of Antibiotics in Manure, Soil, Wastewater, Groundwater from Livestock and Poultry Farms in Xuzhou, China.

Antibiotics in manure, soil, wastewater, and groundwater samples from the livestock and poultry farms in Xuzhou City were investigated in the present study. The concentrations of antibiotics in all matrices varied greatly among farms. Total concentrations of fluoroquinolones and macrolides were much higher than those of sulfonamides in manures and soil samples. Total concentrations of antibiotics in wastewater of livestock farms were higher than those of poultry farm. Josamycin (JM) and tilmicosin (TIL) accounted for more than 74% of the nine macrolides in all groundwater samples. Sulfamethizole (SMT), fleroxacin (FLE), cinoxacin (CIN) and JM were the main antibiotics detected in manure and soil samples, while sulfamethoxypyridazine (SMP), sulfameter (SME), SMT, FLE, JM and TIL accounted for a large proportion of antibiotics in surface and groundwater. The risk assessment of target antibiotics revealed that JM in wastewater showed relatively high RQs for aquatic organisms.

Sulfate radical-based oxidation of the antibiotics sulfamethoxazole, sulfisoxazole, sulfathiazole, and sulfamethizole: The role of five-membered heterocyclic rings.

The widespread occurrence of sulfonamides (SAs) in natural waters, wastewater, soil and sediment has raised increasing concerns about their potential risks to human health and ecological systems. Sulfate radical (SO4-)-based advanced oxidation processes (SR-AOPs) have become promising technologies to remove such contaminants in the environment. The present study systematically investigated the degradation of four selected SAs with different five-membered heterocyclic rings, namely, sulfamethoxazole (SMX), sulfisoxazole (SIX), sulfathiazole (STZ), and sulfamethizole (SMT), by thermo-activated persulfate (PS) process, and the role of heterocyclic rings was assessed particularly. The results revealed that all the selected SAs could be degraded efficiently by thermo-activated PS process and their decay rates were appreciably increased with increasing temperature. For instance, degradation rates of STZ increased from 0.3 × 10-3 to 19.5 × 10-3 min-1 as the temperature was increased from 30 to 60 °C. Under the same experimental conditions, the degradation rates of SAs followed the order of SIX > SMX ≈ STZ > SMT, which was in accordance with decay rates of their R-NH2 moieties. Kinetic results indicated that five-membered heterocyclic rings could serve as reactive moieties toward SO4- attack, which were confirmed by frontier electron density (FED) calculations. Based on the transformation products identified by high-resolution mass spectrometry (HR-MS), five different oxidation pathways, including hydroxylation, aniline moiety oxidation, dimerization, sulfonamide bond cleavage, and heterocyclic ring oxidation/cleavage were proposed. Moreover, the degradation efficiency in real surface water (RSW) was found to be slightly slower than that in artificial surface water (ASW), suggesting that SR-AOPs could be an efficient approach for remediation of soil and water contaminated by these SAs.

Synthesis of Graphene Oxide Based Sponges and Their Study as Sorbents for Sample Preparation of Cow Milk Prior to HPLC Determination of Sulfonamides.

In the present study, a novel, simple, and fast sample preparation technique is described for the determination of four sulfonamides (SAs), namely Sulfathiazole (STZ), sulfamethizole (SMT), sulfadiazine (SDZ), and sulfanilamide (SN) in cow milk prior to HPLC. This method takes advantage of a novel material that combines the extractive properties of graphene oxide (GO) and the known properties of common polyurethane sponge (PU) and that makes sample preparation easy, fast, cheap and efficient. The PU-GO sponge was prepared by an easy and fast procedure and was characterized with FTIR spectroscopy. After the preparation of the sorbent material, a specific extraction protocol was optimized and combined with HPLC-UV determination could be applied for the sensitive analysis of trace SAs in milk. The proposed method showed good linearity while the coefficients of determination (R2) were found to be high (0.991–0.998). Accuracy observed was within the range 90.2–112.1% and precision was less than 12.5%. Limit of quantification for all analytes in milk was 50 μg kg−1. Furthermore, the PU-GO sponge as sorbent material offered a very clean extract, since no matrix effect was observed.

Synthesis, Characterization, in vitro Antifungal Activities and Calf Thymus DNA Interactions of Two Different Hydroxy Benzaldehyde Derivative Schiff Bases from Sulfamethizole: Electrochemical, Spectroscopic and Biological Study

In the present work, the Schiff bases were synthesized by reacting sulfamethizole (SMTZ) with two different hydroxy benzaldehydes (2,3-dihydroxy benzaldehyde (DHBA) and 2,4,6-trihydroxy benzaldehyde (THBA)) and characterized by elemental analysis, 1H-NMR and IR spectroscopies. From the obtained data, it was suggested that 4,6-dihydroxy salicylaldehyde reacted with both primary and secondary amine groups of SMTZ. The binding properties between the synthesized Schiff bases and calf thymus DNA (CT-DNA) at the physiological pH (7.4) was investigated by using cyclic voltammetry and UV-Vis spectroscopy techniques. The experimental results verify that the Schiff bases can bind to CT-DNA by electrostatic mode in 1 : 1 stoichiometry. Antifungal activities of the synthesized Schiff bases against Candida albicans ATCC 10231 were studied and their minimum inhibitory concentrations (MIC) were also determined. The MIC value of the Schiff base 1 synthesized from DHBA is smaller than that of the Schiff base 2 obtained from THBA. Although Schiff base 2 binds to CT-DNA with a higher affinity than Schiff base 1, it is less effective than Schiff base 1 against Candida albicans.