Aqueous Methanol Solution Research Articles

Development and validation of a UHPLC-MS/MS method for the quantitative analysis of trans-ISRIB in human plasma.

The integrated stress response (ISR) is a cellular defense mechanism activated under stress conditions. When the ISR is activated, it slows the production of proteins, the building blocks that cells need to function. Trans-integrated stress response inhibitor (trans-ISRIB) is a compound that can reverse the effects of ISR activation, showing promise for treating neurodegenerative diseases. The preclinical and clinical evaluation of trans-ISRIB necessitates a reliable analytical method. This study presents the development and validation of an ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method for the quantitative analysis of trans-ISRIB in human plasma, conforming to the U.S. FDA's guidelines for bioanalytical method validation. The method developed utilizes a liquid-liquid extraction procedure to prepare plasma samples with a spiked internal standard (IS). The extracts containing trans-ISRIB and the IS were dried under nitrogen, reconstituted in the mobile phase, and separated on a Waters XSelect HSS T3 column under isocratic conditions with a mobile phase containing 0.1% acetic acid in 70% methanol aqueous solution at a flow rate of 0.500mL/min. Detection and quantification were accomplished using a positive electrospray ionization tandem mass spectrometer (ESI+-MS/MS) operated in multiple-reaction-monitoring (MRM) mode. The method demonstrated a linear calibration range for trans-ISRIB concentrations from 0.500 to 1.00x103 nM, with high specificity, precision, accuracy, and recovery. This method addresses a significant analytical gap, offering a robust tool for quantifying trans-ISRIB in human plasma. Chemical compounds studied in this article: 2-(4-chlorophenoxy)-N-[4-[[2-(4-chlorophenoxy)acetyl]amino]cyclohexyl]acetamide (trans-ISRIB) (CAS # 1597403-47-8); 2-(4-chlorophenoxy)-N-(2-{[(4-chlorophenoxy)acetyl]amino}ethyl)acetamide (CAS # 327071-30-7).

Solvent Selection in the Quality Analysis of White Tea by Nuclear Magnetic Resonance Spectroscopy

The study aimed to assess the influence of diverse solvent schemes on the qualitative analysis of white tea and to establish a more comprehensive quality evaluation. A systematic study of solvent optimization was carried out using the quality analysis of white tea as an exemplar, highlighting the critical role of selecting appropriate solvents in NMR-based sample preparation process. Six sample dissolution protocols, encompassing extraction and reconstitution solvents, were evaluated. The aqueous methanol solution proved effective as an extraction solvent, offering optimal metabolite coverage and spectral resolution. For reconstitution solvents, D2O facilitated identification of specific metabolites, such as amino acids, organic acids and carbohydrates, while DMSO-d6 exhibited better performance in detecting catechins, alkaloids and lipid resonances. Additionally, DMSO-d6 enabled better discrimination among various white tea varieties, whereas D2O system demonstrated better ability for estimating the storage duration of white tea. The characteristic metabolites were exactly those that each of the two solvents is suited to solubilize. Therefore, it can be concluded that solvents suitable for the detection of a class of metabolites are more likely to highlight differences in that type of metabolites and multi-solvent combination captures more comprehensive information, revealing the necessity of optimizing solvent protocols for different assay targets.

Spectrophotometric determination of quercetin using micelles of cetyltrimethylammonium bromide in a low ratio methanol–water mixture

A simple and achievable UV-Vis spectrophotometric method for the micro-quantitative determination of quercetin has been developed and validated. This method relies on the formation of supramolecular assemblies of quercetin (QR) and the cationic surfactant cetyltrimethylammonium bromide (CTAB) in a 5 % methanolic aqueous solution. In this solvent medium, CTAB in the presence of QR has a critical micelle concentration of 1.2·10-3 mol l-1 at 24 °C, determined through conductometry. Important analytical parameters such as wavelength, composition of methanol-water mixture, CTAB concentration (cCTAB), and pH were optimized. Under the optimum experimental conditions (l = 397 nm, 5 % methanol as solvent, cCTAB = 2.0·10-3 mol l-1, and pH = 6.0), Beer's law was valid for QR concentrations up to 16.9 mg ml-1. The Ringbom optimum QR concentration range was 1.0 - 16.9 mg ml-1. The method sensitivity was 2.03·104 l mol-1 cm-1 (the molar absorptivity) and 0.13 mg ml-1 (limit of detection). The applicability of the proposed method for quantifying QR in pharmaceutical formulations was demonstrated. Furthermore, the proposed UV-Vis spectrophotometric method was successfully applied to the reliably assay of QR, even in the presence of vitamin C.

Molecular diffusion in aqueous methanol solutions: The combined influence of hydrogen bonding and hydrophobic ends.

Although the nonmonotonic variation in the diffusion coefficients of alcohol and water with changing alcohol concentrations in aqueous solutions has been reported for many years, the underlying physical mechanisms remain unclear. Using molecular dynamics simulations, we investigated the molecular diffusion mechanisms in aqueous methanol solutions. Our findings reveal that the molecular diffusion is co-influenced by hydrogen bonding and the hydrophobic ends of methanol molecules. A stronger hydrogen bond (HB) network and a higher concentration of hydrophobic ends of methanol molecules both enhance molecular correlations, thereby slowing molecular diffusion in the solution. As methanol concentration increases, the HB network weakens, facilitating molecular diffusion. However, the increased concentration of hydrophobic ends counteracts this effect. Consequently, the diffusion coefficients of water and methanol molecules exhibit nonmonotonic changes. Previous studies have only focused on the role of HB networks. For the first time, we have identified the impact of the hydrophobic ends of alcohol on molecular diffusion in aqueous alcohol solutions. Our research contributes to a better understanding and manipulation of the properties of aqueous alcohol solutions and even liquids with complex compositions.

Development of an Impinging Jet Microreactor Synthesis Process for Surfactant‐Free Pt‐Nanoparticles as PEMFC Catalyst Component

AbstractColloidal, surfactant‐free platinum nanoparticles were prepared via a self‐built continuous impinging jet microreactor synthesis process in alkaline aqueous methanol solution (Co4CatTM process). In these syntheses, methanol functions as a reducing agent as well as an additional solvent. Especially the synthesis of surfactant‐free nanoparticles remained challenging, and additionally, the transfer of this synthesis into a continuous process required several optimization steps. In this contribution we present highly controllable final particle sizes by adjusting process temperature, platinum precursor concentration and molar ratio of the hydroxide and platinum precursor used. The size objective of the surfactant‐free Pt nanoparticles was a range of 1 – 10 nm, due to the intended application in various catalytic processes, especially as PEMFC electrocatalyst. Dynamic light scattering (DLS), ζ‐potential measurements, transmission electron microscopy (TEM) and UV/Vis spectroscopy were used to monitor the particle stability over a certain period of time and study the rate of the reduction reaction in more detail.

Vacancy-Induced Symmetry Breaking in Titanium Dioxide Boosts the Photocatalytic Hydrogen Production from Methanol Aqueous Solution.

The key to optimizing photocatalysts lies in the efficient separation and oriented migration of the photogenerated carriers. Herein, we report that breaking continuous TiO6 tetragonal (D4h) symmetry in titanium dioxide material by oxygen vacancy engineering could induce a dipole field within the bulk phase and thus facilitate the separation and transfer of photogenerated electron-hole pairs. After further loading of Cu single-atom co-catalysts, the obtained catalyst attained a hydrogen (H2) yield rate of 15.84 mmol g-1 h-1 and a remarkable apparent quantum yield of 12.67% at 385 nm from methanol aqueous solution. This catalyst also demonstrated impressive stability for at least 24 h during the photocatalytic tests. The innovative concept of producing dipole fields in semiconductors by breaking the crystal symmetry offers a new perspective for designing photocatalysts.

Tailoring sub-5 nm Fe-doped CeO2 nanocrystals within confined spaces to boost photocatalytic hydrogen evolution under visible light

This work aimed to study the efficiency of the reverse micelle (RM) preparation route in the syntheses of sub-5 nm Fe-doped CeO2 nanocrystals for boosting the visible-light-driven photocatalytic hydrogen production from methanol aqueous solutions. The effectiveness of confining precipitation reactions within micellar cages was evaluated through extensive physicochemical characterization. In particular, the nominal composition (0–5 mol% Fe) was preserved as ascertained by ICP-MS analysis, and the absence of separate iron-containing crystalline phases was supported by X-ray diffraction. The effective aliovalent doping and modulation of the optical properties were investigated using UV-Vis, Raman, and photoluminescence spectroscopies. 2.5 mol% iron was found to be an optimal content to achieve a significant decrease in the band gap, enhance the concentration of oxygen vacancy defects, and increase the charge carrier lifetime. The photocatalytic activity of Fe-doped CeO2 prepared at different Fe contents with RM preparation was studied and compared with undoped CeO2. The optimal iron load was identified to be 2.5 mol%, achieving the highest hydrogen production (7566 μmol L−1 after 240 min under visible light). Moreover, for comparison, the conventional precipitation (P) method was adopted to prepare iron containing CeO2 at the optimal content (2.5 mol% Fe). The Fe-doped CeO2 catalyst prepared by RM showed a significantly higher hydrogen production than that obtained with the sample prepared by the P method. The optimal Fe-doped CeO2, prepared by the RM method, was stable for six reuse cycles. Moreover, the role of water in the mechanism of photocatalytic hydrogen evolution under visible light was studied through the test in the presence of D2O. The obtained results evidenced that hydrogen was produced from the reduction of H+ by the electrons promoted in the conduction band, while methanol was preferentially oxidized by the photogenerated positive holes.

A new synthesis of indolo[2,3-b]quinolines from 3-acetyl-N-alkyl-2-chloroindoles with 2-aminobenzophenone.

A new synthesis of N-alkyl- and 11-phenyl-modified indolo[2,3-b]quinolines was achieved via PEG-400-promoted and visible light-induced one-step reaction of 3-acetyl-N-alkyl-2-chloroindoles with 2-aminobenzophenone in 40% methanol aqueous solution. The merits of the protocol include cost efficiency, convenience, and eco- and user-friendliness.

Determination of eight neonicotinoid pesticides in wastewater by solid phase extraction combined with liquid chromatography-tandem mass spectrometry

Neonicotinoid pesticides are a relatively new class of pesticides that have garnered significant attention owing to their potential ecological risks to nontarget organisms. A method combining solid phase extraction with liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS) was developed for the rapid and accurate detection of eight neonicotinoid pesticides (dinotefuran, E-nitenpyram, thiamethoxam, clothianidin, imidacloprid, imidaclothiz, acetamiprid, and thiacloprid) in wastewater. The chromatographic mobile phase and MS parameters were selected, and a single-factor method was used to determine the optimal column type, extraction volume, sample loading speed, and pH for SPE. The optimal parameters were as follows: column type, HLB column (500 mg/6 mL); sample extraction volume, 500 mL; sample loading speed, 10 mL/min; and sample pH, 6-8. The matrix effects of the wastewater samples were reduced by optimizing the chromatographic gradient-elution program, examining the dilution factor of the samples, and using the isotope internal standard calibration method. Prior to analysis, the wastewater samples were diluted 5-fold with ultrapure water for pretreatment. Subsequently, 2 mmol/L ammonium acetate aqueous solution containing 0.1% (v/v) formic acid and methanol was used as mobile phases for gradient elution on a ZORBAX Eclipse Plus C18 column (100 mm×2.1 mm, 1.8 μm). The samples were quantified using positive-ion multiple reaction monitoring (MRM) mode for 10 min. Imidacloprid-d4 was used as the isotope internal standard. The SPE process was further optimized by applying response surface methodology to select the type and mass of rinsing and elution solvents. The optimal pretreatment of the SPE column included rinsing with 10% methanol aqueous solution and elution with methanol-acetonitrile (1∶1, v/v) mixture (7 mL). The eight neonicotinoid pesticides showed satisfactory linearity within the relevant range, with linear correlation coefficients (r) all greater than 0.9990. The method detection limits (MDLs) ranged from 0.2 to 1.2 ng/L, and the method quantification limits (MQLs) ranged from 0.8 to 4.8 ng/L. The average recoveries of the eight neonicotinoid pesticides were in the range of 82.6%-94.2% at three spiked levels, with relative standard deviations (RSDs) ranging from 3.9% to 9.4%. Finally, the optimized method was successfully applied to analyze wastewater samples collected from four sewage treatment plants. The results indicated that the eight neonicotinoid pesticides could be generally detected at concentrations ranging from not detected (ND) to 256 ng/L. The developed method has a low MDL and high accuracy, rendering it a suitable choice for the trace detection of the eight neonicotinoid pesticides in wastewater when compared with other similar methods. The proposed method can be utilized to monitor the environmental impact and assess the potential risks of neonicotinoid pesticides in wastewater, thus promoting the protection of nontarget organisms and the sustainable use of these pesticides in agriculture.

Thermodynamic modelling of gas hydrate dissociation conditions in porous medium in the presence of NaCl/methanol aqueous solution

AbstractDue to the growing significance of the existence of gas hydrates in natural media like the ocean floor/permafrost regions and the extraction of natural gas from hydrate reservoirs using thermodynamic hydrate inhibitors, investigating the dissociation of gas hydrates in porous media in the presence of inhibitors is crucial. This work examines a broad range of laboratory data on the dissociation conditions of gas hydrates in the porous mediums when salt/alcohol aqueous solutions are present. The temperature of gas hydrate dissociation in the presence of pure water is calculated using the van der Waals–Platteeuw solid solution theory. The water activity in the porous medium is then calculated by taking into account a number of variables, including the radius of the porous medium, molar volume, shape factor, wetting angle, and surface tension. The Pitzer and Margules activity coefficient models are used to determine the water activity in the presence of salt and alcohol, respectively. Lastly, the gas hydrate dissociation temperature in a porous medium in the presence of salt and/or alcohol aqueous solution is determined by combining Piereon's model with an enthalpy‐based correlation that was proposed by Azimi et al. The selected package can consistently correlate the gas hydrate dissociation conditions in a porous medium in the presence of alcohol or salt aqueous solution. The average absolute deviation (AAD) of 0.67 K for the whole data bank (90 experimental data points) shows the precision of the model.

Development and validation of the method of quantification of 5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide and its metabolites in laboratory animal plasma

Introduction. The study of the systemic exposure of a new original drug is an essential part of its preclinical study. 5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide is a new selective carbonic anhydrase II inhibitor for the treatment of open-angle glaucoma. Methods for the quantitative determination of this compound and its N-hydroxy- and N-acetyl metabolites in the plasma of laboratory animals have not been previously developed.Aim. Development and validation of a method of quantitative determination of 5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide and its metabolites N-hydroxy-5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide (M1) and N-acetyl-5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide (M2) in rat and rabbit blood plasma by HPLC-MS/MS.Materials and methods. Protein precipitation by methanol was applied for sample preparation. 5-[2-(morpholine-4-carbonyl)-1,3-oxazole-5-yl]-thiophene-2-sulfonamide was used as an internal standard. A 5 % aqueous solution of ascorbic acid was added to the plasma samples at volume ratio 1 : 2 to prevent decomposition of N-hydroxy-5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide. The combination of sodium fluoride and potassium oxalate was selected as an anticoagulant. Chromatographic separation was performed on Zorbax Eclipse Plus C18 column (150 × 3.0 mm, 3.5 µm) with Zorbax Eclipse Plus C18 pre-column (12.5 × 2.1 mm, 5.0 µm) using a mobile phase based on a 0.1 % aqueous solution of formic acid and methanol. Mass spectrometric detection was carried out in the MRM mode using electrospray ionization in negative polarity. The method was tested during a pharmacokinetic study of a 1 % ocular suspension of 5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide on 6 Wistar rats. Blood samples were collected before administration, as well as 30 min, 1 h, 1 h 30 min, 2 h, 3 h, 4 h, 6 h, 8 h, 12 h, 24 h, 48 h, 72 h, 144 h, 216 h after administration. The non-compartment approach was used for calculation pharmacokinetic parameters.Results and discussion. The developed method has been validated in parameters of selectivity, calibration curve, accuracy and precision, matrix effect, dilution integrity, carry over, reinjection reproducibility, stability. The analytical range of determination of 5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide in plasma was 10–4000 ng/ml, M1 – 1.0–400.0 ng/ml, M2 – 0.1–40.0 ng/ml. The selected combination of anticoagulant and stabilizer solution allows storage of plasma samples in freezing chamber for 28 days.Conclusion. The developed method has been fully validated and confirmed its suitability for quantitative determination of 5-[5-(trifluoromethyl)-1,2-oxazole-3-yl]-furan-2-sulfonamide and its metabolites in the blood plasma of laboratory animals. The method has been successfully used for pharmacokinetic study of 1 % ocular suspension of the drug.

High-Dimensional Nb2O5 with NbO6 Octahedra for Efficient Electrocatalytic Upgrading of Methanol to Formate.

Facilitating the selective electrochemical oxidation of methanol into value-added formate is essential for electrochemical refining. Here we propose a high-dimensional Nb2O5 on Ni foam (Nb2O5-HD@NF) composite as anode for methanol oxidation reaction (MOR) for efficient production of formate. In an electrolyte containing 3 M methanol aqueous solution, the Nb2O5-HD@NF anode requires only 240 mV overpotential to deliver an industrial-level current density of 100 mA cm-2 with a formate Faraday efficiency of 100%. In situ Raman and electrochemical kinetic analyses reveal that the origin of the excellent activity in 3 M methanol electrolyte can be ascribed to the NbO6 octahedra as active sites and the Lewis acid sites on the surface of Nb2O5-HD. This work may pave a way for the design of non-noble metal electrocatalysts with surface acidity engineering for the effective electrocatalytic upgrading of biomass molecules.

EFFECT OF SNO2 POROUS STRUCTURE ON ITS OPTICAL AND PHOTOELECTROCHEMICAL PROPERTIES IN WATER AND WATER-METHANOL SOLUTIONS

Tin(IV) oxide is a wide-gap semiconductor material that is widely used in photooxidation reactions of organic compounds. However, the relationship between energetic and photoelectrocatalytic properties in the oxidation of small organic molecules has not yet been sufficiently explored. In this work, a series of tin oxides were synthesized using hydrothermal, sol-gel, and template methods. Polystyrene spheres with a size of 250 nm, as well as cetyltrimethylammonium bromide, were used as templates. X-Ray diffraction, low-temperature nitrogen adsorption, X-ray photoelectron spectroscopy, Raman spectroscopy and diffuse reflectance spectroscopy methods were used to study the structure, surface composition, optical and energy characteristics. Using photoelectrochemical methods, the potentials of the conduction band and valence band were determined, and photocurrents in aqueous and aqueous-methanol solutions were studied depending on electrode polarization. It is shown that the preparation method (sol-gel or hydrothermal) does not affect the position of energy bands, while the use of a template during synthesis leads to an increase in the average pore diameter in the samples and an increase in photocurrent values in the presence of methanol. It has been established that for template-synthesized samples, the magnitude of photocurrents in a water-methanol mixture increases with an increase in the valence-band potential. The sample prepared by the hydrothermal method using a template showed the highest photocurrent values both in the background electrolyte (17.3 μA/cm2) and in the presence of methanol (26 μA/cm2), compared to the sample prepared without using a template in the electrolyte with the addition of methanol (7.6 μA/cm2) and without it (7.8 μA/cm2).

Detection of trace levels of selected allergic chemicals in commercial hair dyes in local market of Jeddah, Saudi Arabia

Hair dyes are now commonly used in Saudi Arabia, and other nations across the world, to cover up grey hairs and/or to modify the natural color of the hair. The principal ingredients of hair dyes are aromatic amines and phenols and which most likely cause allergic reactions, irritated skin, and even cancer in certain cases. Thus, the current study reports the separation and subsequent identification of four chemical constituents namely p-Phenylenediamine (PPD), 3-aminophenol (3AP), resorcinol (RES), and 2-methylresorcinol (2MRS) in 26 commercial hair dyes that represent ten famous brands available in the local market of Jeddah city, Saudi Arabia. High-performance liquid chromatography (HPLC) technique was successfully employed to identify the four chemical compounds using methanol-aqueous solution (10:90 v/v) containing diethanolamine (0.05 %) and ammonium acetate (0.02 M) at pH 5.2 as a proper mobile phase. The column was 150 × 4.6 mm ID and 5 µm Eclipse Plus C18 column and the retention times were 1.26, 3.16, 4.99 and 6.01 min for PPD, 3AP, RES, and 2MRS, respectively. The four standards PPD, 3AP, RES, and 2MRS at 254 nm displayed excellent linear calibration plots in the concentration range 5–100 µg/mL with acceptable correlation coefficients (R2) of 0.9964, 0.9980, 0.9952 and 0.9961, respectively. The low limits of detection (LOD) and quantification (LOQ) based on the standard deviation of the response and the slopes of the plots were found to be equal 7.17, 5.39, 8.33, and 7.47 µg/mL and 23.91, 17.97, 27.75, 24.89 µg/mL for PPD, 3AP, RES, and 2MRS, respectively.

Preparation and application of highly oriented MFI zeolite membranes for efficient pervaporation recovery of organic solvents

Membrane-based pervaporation (PV) is highly efficient and energy-saving, and is poised to emerge as a promising technology for recovering biofuels from aqueous solutions. In this study, we prepared two versions of zeolite membranes, randomly oriented and highly (h0h)-oriented silicalite-1, with similar thicknesses on α-alumina tubes, and performed the first-reported systematic comparison of their PV performances in recovering organic solvents such as methanol, ethanol, acetone, n-propanol, isopropanol, and n-butanol from water. The contribution of the intrinsic properties of these membranes to PV was explored through permeance and selectivity analysis. The highly (h0h)-oriented membrane exhibited a significantly higher level of PV performance. In addition, the permeation behavior of PV and single-gas molecules through the highly (h0h)-oriented membranes was investigated, along with the influence that operating conditions (feed temperature and concentration) exert on PV. The results suggest that the PV permeation mechanism of organic solvent/water systems through the (h0h)-oriented silicalite-1 membranes involves a combination of adsorption-diffusion and molecular sieving. Furthermore, compared with other MFI-based membranes reported in the literature, the highly (h0h)-oriented silicalite-1 membrane demonstrated outstanding comprehensive separation performance due to its highly hydrophobic, preferentially oriented, and uniform silicalite-1 layer. For example, the separation factors for 10 wt% binary aqueous solutions of methanol, ethanol, acetone, and n-propanol were 12 at 50 °C, 32 at 70 °C, 145 at 70 °C, and 37.7 at 50 °C, respectively, with corresponding total flux values of 4.18, 2.63, 2.5, and 0.29 kg/(m2 h), respectively. These unique properties suggest its potential for PV recovery of organic solvents in sustainable chemical engineering.

Arsenate Stabilization via Dynamic Covalent Chemistry

AbstractWe report the synthesis of arsenic heterocycles derived from saccharides 2–4 and AsCl3. Compounds 5 and 6 are stable in aqueous solutions, DMSO, or methanolic solutions. However, NMR and HPLC studies revealed that intramolecular trans‐esterification processes leads to dynamic equilibria. Theoretical studies revealed that three arsenates and two arsoranes participate in these intramolecular equilibria and account for the experimental spectroscopy and HPLC results. Through the correlation between the experimental and theoretical 13C NMR spectra, we proposed the speciation of arsenic Compounds 5 and 6. Moreover, experimental and theoretical IR spectra demonstrated that arsenates 5 A and 6 A predominate in the solid state. QTAIM studies were performed to explain the chemical shifts in the 13C NMR spectra. Biological studies suggest that the structural flexibility of Compounds 5 and 6 increase the cytotoxic and antiproliferative activities of these compounds.

Novel strategies for the determination of plastic additives derived from agricultural plastics in soil using ultrahigh-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS)

Certain agricultural plastics, i.e., mulching films, are generally considered as potent sources of micro- and nanoplastics (MNPs), due to their direct application on soil and waste mishandling. During the synthesis and fabrication of such agricultural plastics, it is necessary to use chemicals, the so-called plastic additives (PAs), improving the physicochemical properties of the final polymeric product. However, since PAs are loosely bound on the polymer matrix, they can potentially leach into the soil environment with unidentified effects. Clearly, to monitor the fate of PAs in the terrestrial ecosystem, it is necessary to develop accurate, sensitive and robust analytical methods. To this end, a comprehensive analytical strategy was developed for monitoring 16 PAs with diverse physicochemical properties (partition coefficient; −3 < logP<19) in soil samples using ultra-high-performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). For this purpose, two different extraction procedures were developed, namely, a single step ultrasound-assisted extraction (UAE) using ethyl acetate or an aqueous solution of methanol and a binary extraction, combining Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) and UAE principles with n-hexane as the extractant. Interestingly, within the sample preparation investigation, we identified in-lab contamination sources of PAs, e.g., centrifuge tubes or microfilters. Such consumables are made of plastic contaminating the procedural blanks and omitting their use was necessary to acquire satisfactory analytical performance. In detail, method validation was performed for 16 compounds achieving recoveries mainly in the range 70–120 %, repeatability (expressed as relative standard deviation, RSD %) < 20 % and limits of quantification (LOQs) ranging between 0.2 and 20 ng/g dry weight (dw). Importantly, the presented strategies are added to the very limited available for PA determination in soil, a topical issue with a significant and rather understudied impact on agriculture.

Polyphenolic Profiling and Antioxidant Activity in Berry Extracts of Pyracantha Wild Varieties from the Mediterranean Region.

Pyracantha is a genus of wild perennial shrubs native in an area extending from Southwest Europe to Southeast Asia, and it is used in traditional medicine for the diuretic, cardiac, and tonic properties of its fruits, which can also be cooked to make jellies, jams, and sauces. This work aims to study and compare the antioxidant activity and the phenolic and anthocyanin composition of three varieties of Pyracantha coccinea: Red Column (PCR), Orange Glow (PCO), and Soleil d'Or (PCS), and one of Pyracantha angustifolia: Orange glow (PAO), collected from the spontaneous flora of the Mediterranean region (Southern Italy). Two different extraction processes were tested using methanol and an aqueous methanol solution (80% MeOH) to evaluate the polyphenolic content and antioxidant activity of freeze-dried berries. The highest total phenolic content was found in PCR and PAO berries (174.21 ± 0.149 and 168.01 ± 0.691 mg of gallic acid equivalent per gram of dry matter, respectively) extracted with an aqueous methanol solution (80% MeOH). Polyphenolic extracts analyzed by HPLC-DAD-ESI/MS confirmed the presence of rutin, quercetin hexose, neoeriocitrin, procyanidin B, and resveratrol. Moreover, the total antioxidant activity of the berries' extracts was measured by comparing two different spectrophotometric methods (ABTS and DPPH), showing that the varieties with the highest total phenolic content, PCR and PAO, also had the highest scavenging activity. Finally, a suitable extraction process was chosen for the evaluation of the anthocyanins' composition of all frozen berries, and in all MS spectra of Pyracantha varieties, two ionic species at 449 m/z attributable to two cyanidin derivatives were found.

Facile synthesis of CuOx-decorated TiO2 nanoparticles via oxygen-limited pyrolysis of Cu(II) complex for efficient photocatalytic hydrogen evolution

CuOx-decorated TiO2 (CuOx/TiO2) nanoparticles have been prepared by the pyrolysis of Cu(II) complex on TiO2 in an oxygen-limited atmosphere. A solution phase deposition method combined with freeze drying was employed for depositing the 2-methylimidazole-Cu(II) complex onto TiO2 nanoparticles. The effect of decoration of CuOx on TiO2 nanoparticles in terms of the crystal phase, morphology, chemical compositions, surface area, surface elemental states, optical absorption and emission properties, was investigated using a series of characterization tools. The oxygen-limited pyrolysis of 2-methylimidazole resulted in the reduction of partial Ti4+ and Cu2+ ions into Ti3+, Cu+ and Cu0 species, respectively. The surface decoration of CuOx was found to improve the separation and migration of photogenerated electron-hole pairs and increase the life time of excitons. Furthermore, the photocatalytic performance of CuOx/TiO2 nanoparticles was evaluated for hydrogen evolution in aqueous methanol solution under UV–visible light irradiation. The CuOx/TiO2 photocatalyst with the optimal cocatalyst loading achieved hydrogen evolution rate of 4.34 mmol h−1 g−1, with 71- and 5.5-fold enhancement in activity over neat TiO2 and CuOx/P25, respectively. It is expected that the combination of deposition and pyrolysis of 2-methylimidazole-Cu(II) complex could be an effective approach for the decoration of Cu and its oxides on other supports.

Efficient Charge Transfer of p-n Heterojunction UiO-66-NH2/CuFe2O4 Composite for Photocatalytic Hydrogen Production

Using a p-n heterojunction is one of the efficient methods to increase charge transfer in photocatalysis applications. So, herein, p-type UiO-66 (NH2) and n-type CuFe2O4 (CFO) are used to form an effective p-n heterojunction. Due to their poor charge separation in their pristine form, both UiO-66 (NH2) and CFO materials cannot produce hydrogen; however, the composite p-n heterojunction formed between these materials makes fast charge separation and so hydrogen is efficiently produced. The optimized catalyst UCFO 25% produces a maximum of 62.5 µmol/g/h hydrogen in an aqueous methanol solution. The formation of a p-n heterojunction is confirmed by Mott–Schottky analysis and optical properties, crystallinity and the local atomic environment of the material was analyzed by various analytical tools like UV-Vis spectroscopy, XRD, and XANES.