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Chemosphere Aug 2024This study aims the characterization of several tianeptine transformation products in ultrapure water by simulated sunlight irradiation. Tianeptine was completely...
This study aims the characterization of several tianeptine transformation products in ultrapure water by simulated sunlight irradiation. Tianeptine was completely degraded after 106 h of exposition following pseudo-first-order kinetics (half-life time = 12.0 ± 2.4 h). Furthermore, an ultra-high-performance liquid chromatography coupled with a high-resolution quadrupole time-of-flight-mass spectrometry method was developed and fully validated taking into account different method performance parameters for the quantification of tianeptine in river water up to a concentration of 400 pg L. Following a non-targeted approach based on mass data-independent acquisition, eight different transformation products not previously reported in the literature were identified and accordingly elucidated, proposing a photodegradation mechanism based on the accurate tandem mass spectrometry information acquired. Irradiation experiments were replicated for a tianeptine solution prepared in a blank river water sample, resulting in the formation of the same transformation products and similar degradation kinetics. In addition, a toxicity assessment of the photoproducts was performed by in silico method, being generally all TPs of comparable toxicity to the precursor except for TP1, and showing a similar persistence in the environment except for TP2 and TP6, while TP4 was the only TP predicted as mutagenic. The developed method was applied for the analysis of four river water samples.
Topics: Water Pollutants, Chemical; Tandem Mass Spectrometry; Chromatography, High Pressure Liquid; Photolysis; Thiazepines; Rivers; Kinetics; Sunlight
PubMed: 38849097
DOI: 10.1016/j.chemosphere.2024.142534 -
Analytical Chemistry Jun 2024Biopharmaceuticals, such as monoclonal antibodies (mAbs), need to maintain their chemical and physical stability in formulations throughout their lifecycle. It is known...
Biopharmaceuticals, such as monoclonal antibodies (mAbs), need to maintain their chemical and physical stability in formulations throughout their lifecycle. It is known that exposure of mAbs to light, particularly UV, triggers chemical and physical degradation, which can be exacerbated by trace amounts of photosensitizers in the formulation. Although routine assessments of degradation following defined UV dosages are performed, there is a fundamental lack of understanding regarding the intermediates, transient reactive species, and radicals formed during illumination, as well as their lifetimes and immediate impact post-illumination. In this study, we used light-coupled NMR spectroscopy to monitor in situ live spectral changes in sealed samples during and after UV-A illumination of different formulations of four mAbs without added photosensitizers. We observed a complex evolution of spectra, reflecting the appearance within minutes of transient radicals during illumination and persisting for minutes to tens of minutes after the light was switched off. Both mAb and excipient signals were strongly affected by illumination, with some exhibiting fast irreversible photodegradation and others exhibiting partial recovery in the dark. These effects varied depending on the mAb and the presence of excipients, such as polysorbate 80 (PS80) and methionine. Complementary ex situ high-performance size-exclusion chromatography analysis of the same formulations post-UV exposure in the chamber revealed significant loss of purity, confirming formulation-dependent degradation. Both approaches suggested the presence of degradation processes initiated by light but continuing in the dark. Further studies on photoreaction intermediates and transient reactive species may help mitigate the impact of light on biopharmaceutical degradation.
Topics: Antibodies, Monoclonal; Ultraviolet Rays; Magnetic Resonance Spectroscopy; Photolysis; Drug Compounding; Drug Stability; Light
PubMed: 38847283
DOI: 10.1021/acs.analchem.4c01164 -
The Journal of Physical Chemistry. A Jun 2024The development of the velocity map ion imaging (VMI) technique has greatly advanced the study of photodissociation dynamics. The high-resolution imaging study of the...
The development of the velocity map ion imaging (VMI) technique has greatly advanced the study of photodissociation dynamics. The high-resolution imaging study of the photodissociation allows for the acquisition of precise and detailed information on the fragments. This information can further provide more insight into the energy partition and potential pathways involved in the photodissociation process. In this study, we report the investigation on the photodissociation of OCS via the AΠ states following the excitation of AΠ (ν 0 ν) ← XΠ (0 0 0) by using time-sliced VMI techniques in the ultraviolet region. Our investigation revealed significant mode-dependent recoil anisotropies and branching ratios of two product channels for both Ω = 1/2 and Ω = 3/2. The photolysis products also exhibited dramatic deviation in angular distributions and generally comparable kinetic energy distributions following the excitation to the same vibrational modes of AΠ states with two separate spin-orbit components. According to the observation in this study and previously reported photodissociation mechanisms of the OCS cations, the decay from the AΠ state was more likely via the internal conversion to high rovibrational states of the XΠ state, in comparison to the AΠ state.
PubMed: 38840312
DOI: 10.1021/acs.jpca.4c01358 -
Chemosphere Aug 2024Selecting safe, non-toxic, and non-metallic semiconductor materials that facilitate the degradation of pollutants in water stands out as an optimal approach to combat...
Selecting safe, non-toxic, and non-metallic semiconductor materials that facilitate the degradation of pollutants in water stands out as an optimal approach to combat environmental pollution. Herein, graphitic carbon nitride (g-CN)-based hollow nanospheres nonmetallic photocatalyst modified with covalent organic framework materials named TpMA, based on 1, 3, 5-trimethylchloroglucuronide (Tp) and melamine (MA), was successfully synthesized (abbreviated as CNTP). The ordered electron donor-acceptor structure inherent in TpMA contributed to enhancing the transport efficiency of photogenerated carriers in CNTP. The CNTP photocatalysts exhibited excellent performance in degrading rhodamine B and tetracycline in visible light, with optimal degradation rates reached more than 90% in 60 and 80 min, respectively, which were 5.3 and 3.0 times higher than those of pure CNNS. The increased photocatalytic efficiency observed in CNTP composites could be traced back to the covalently connection between the two molecules, forming a π-conjugated system that facilitated the separative efficiency of photogenerated electron-hole pairs and intensified the utilization of visible light. This study provided a new means to design and fabricate highly efficient and environmentally friendly non-metallic photocatalytic materials.
Topics: Nanospheres; Catalysis; Triazines; Graphite; Rhodamines; Nitrogen Compounds; Water Pollutants, Chemical; Light; Tetracycline; Nitriles; Photochemical Processes; Photolysis
PubMed: 38838869
DOI: 10.1016/j.chemosphere.2024.142522 -
The Journal of Chemical Physics Jun 2024The spur reaction, a spatially nonhomogeneous chemical reaction following ionization, is crucial in radiolysis or photolysis in liquids, but the spur expansion process...
The spur reaction, a spatially nonhomogeneous chemical reaction following ionization, is crucial in radiolysis or photolysis in liquids, but the spur expansion process has yet to be elucidated. One reason is the need to understand the role of the dielectric response of the solvating molecules surrounding the charged species generated by ionization. The dielectric response corresponds to the time evolution of the permittivity and might affect the chemical reaction-diffusion of the species in a spur expansion process. This study examined the competitive relationship between reaction-diffusion kinetics and the dielectric response by solving the Debye-Smoluchowski equation while considering the dielectric response. The Coulomb force between the charged species gradually decreases with the dielectric response. Our calculation results found a condition where fast recombination occurs before the dielectric response is complete. Although it has been reported that the primary G-values of free electrons depend on the static dielectric constant under low-linear-energy transfer radiation-induced ionization, we propose that considering the dielectric response can provide a deeper insight into fast recombination reactions under high-linear-energy transfer radiation- or photo-induced ionization. Our simulation method enables the understanding of fast radiation-induced phenomena in liquids.
PubMed: 38836449
DOI: 10.1063/5.0211089 -
Communications Chemistry Jun 2024Photolysis is an attractive method in organic synthesis to produce free radicals through direct bond cleavage. However, in this method, specific irradiation wavelengths...
Photolysis is an attractive method in organic synthesis to produce free radicals through direct bond cleavage. However, in this method, specific irradiation wavelengths of light have been considered indispensable for excitation through S-S or S-T transitions. Here we report the photoinduced homolysis of electronegative interelement bonds using light at wavelengths much longer than theoretically and spectroscopically predicted for the S-S or S-T transitions. This long-wavelength photolysis proceeds in N-Cl, N-F, and O-Cl bonds at room temperature under blue, green, and red LED irradiation, initiating diverse radical reactions. Through experimental, spectroscopic, and computational studies, we propose that this "hidden" absorption is accessible via electronic excitations from naturally occurring vibrationally excited ground states to unbonded excited states and is due to the electron-pair repulsion between electronegative atoms.
PubMed: 38834838
DOI: 10.1038/s42004-024-01208-0 -
Nature Materials Jun 2024
PubMed: 38834730
DOI: 10.1038/s41563-024-01879-z -
Chemosphere Aug 2024The natural phototransformation of organic pollutants in the environment depends on several water constituents, including inorganic ions, humic substances, and pH....
The natural phototransformation of organic pollutants in the environment depends on several water constituents, including inorganic ions, humic substances, and pH. However, the literature information concerning the influence of various water components on the amount of phototransformation and their impact on the development of various transformation products (TPs) is minimal. This study investigated the phototransformation of ofloxacin (OFL), a fluoroquinolone antibiotic, in the presence of various water components such as cations (K, Na, Ca, NH, Mg), anions (NO, SO, HCO, CO, PO), pH, and humic substances when exposed to natural sunlight. The study reveals that neutral pH levels (0.39374 min⁻) enhance the phototransformation of OFL in aquatic environments. Carbonate, among anions, shows the highest rate constant (2.89966 min⁻), significantly influencing OFL phototransformation, while all anions exhibit a notable impact. In aquatic environments, indirect phototransformation of OFL, driven by increased reactive oxygen species, expedites light-induced reactions, potentially enhancing OFL phototransformation. A clear difference was visible in the type of transformation products (TPs) formed during direct and indirect photolysis. The impact of indirect photolysis in the product profile was evaluated by examining the unique properties of TPs in direct and indirect photolysis. The primary transformation products were generated by oxidation and cleavage processes directed towards the ofloxacin piperazinyl, oxazine, and carboxyl groups. The toxicity assessment of TPs derived from OFL revealed that among the 26 identified TPs, TP3 (demethylated product), TP7 and TP8 (decarboxylated products), and TP15 (piperazine ring cleaved product) could potentially have some toxicological effects. These findings suggest that the phototransformation of OFL in the presence of various water components is necessary when assessing this antibiotic's environmental fate.
Topics: Ofloxacin; Photolysis; Water Pollutants, Chemical; Humic Substances; Sunlight; Hydrogen-Ion Concentration; Anti-Bacterial Agents; Reactive Oxygen Species
PubMed: 38830465
DOI: 10.1016/j.chemosphere.2024.142484 -
Spectrochimica Acta. Part A, Molecular... Oct 2024This study investigates the utilization of carbon dots (CDs) from neem leaves (Azadirachta indica) decorated onto cadmium sulfide (CdS) for the photocatalytic...
This study investigates the utilization of carbon dots (CDs) from neem leaves (Azadirachta indica) decorated onto cadmium sulfide (CdS) for the photocatalytic degradation of ciprofloxacin. A comparative study of ciprofloxacin degradation with pristine CdS and CD decorated CdS demonstrated high degradation of ∼ 75 % with CD/CdS when compared to bare CdS (∼68 %). Process optimization studies were further carried out with CD/CdS catalysts at different solution pH (4-10), feed concentrations (10-50 mg/L), catalyst loadings (25-125 mg/L), temperatures (10 - 30 °C), and lamp power (25, 50, 250 W and sunlight). Higher temperatures, combined with a solution pH of 7 and catalyst loading of 100 mg/L favored the enhanced degradation of 20 mg/L of ciprofloxacin. The ciprofloxacin degradation rate increased linearly with temperature with an apparent activation energy of 27 kJ mol. The CD/CdS photocatalyst demonstrated maximum degradation rates with higher lamp powers while it also showed remarkable performance under natural sunlight achieving the same degradation within 3 h.
Topics: Ciprofloxacin; Sulfides; Cadmium Compounds; Catalysis; Carbon; Quantum Dots; Temperature; Nanostructures; Hydrogen-Ion Concentration; Photolysis
PubMed: 38830330
DOI: 10.1016/j.saa.2024.124572 -
Physical Chemistry Chemical Physics :... Jun 2024Sulfur compounds (SO, CS, HS and OCS) are common toxic pollutants in the atmospheric environment, and the absorption spectroscopy technique can indeed help to realize...
Sulfur compounds (SO, CS, HS and OCS) are common toxic pollutants in the atmospheric environment, and the absorption spectroscopy technique can indeed help to realize online monitoring of their concentrations. However, nonlinear effects that occur during absorption spectroscopy measurements have a serious impact on the measurement of the absorption cross-sections (ACSs) of sulfur compounds, leading to serious deviations in both the substance absorption properties and concentrations obtained based on ACS analysis. In this paper, the maximum effective ACSs of sulfur compounds in the linear region are obtained by considering the influence of nonlinear effects and eliminating interference factors such as oxygen and photolysis. In addition, the nonlinear effects are found to be greatly attenuated in spectra with broad band absorption characteristics by comparing the oscillatory absorption spectra before and after the differential treatment and by comparing the change in the oscillatory ACS with the broad band ACS. The experimental results show that the effective ACSs of SO, CS, HS, and OCS with a resolution of 0.23 nm are 14.15 × 10 cm per molecule, 5.61 × 10 cm per molecule, 7.09 × 10 cm per molecule, and 3.20 × 10 cm per molecule, respectively. So far, it is the largest ACS obtained at room temperature and atmospheric pressure, which is of great significance for online measurement of sulfur compounds.
PubMed: 38828761
DOI: 10.1039/d3cp05881f