Acetic Anhydride Research Articles

Endocrine disruptors in Adansonia digitata (Linn) extract induce alteration of female Wistar rats’ oestrous cycle, hormone and lipid profiles

ObjectiveHexane-acetyl acetate (HAAF) and acetyl acetate–methanol fractions (AAMF) but not aqueous methanol (AQMF) and aqueous fractions (AQF) of Adansonia digitata Linn root bark induce reproductive effects in female Wistar rats. The current study investigated the exclusive components of HAAF, AAMF, AQMF, and AQF of Adansonia digitata Linn root bark and the effect of AAMF on the female Wistar rat's oestrous cycle progression, and hormone and lipid profiles. MethodologyGas chromatography and mass spectrometry explored the components of HAAF, AAMF, AQMF, and AQF. Mature female Wistar rats with a proven 4–5-days oestrous cycle were synchronised and randomly assigned into three treatment groups of 30 rats each on the day of proestrus. For seven days, rats in the different groups received 0, 150, and 300 mg kg-1 body weights of AAMF, respectively. Six rats were euthanised from each group based on a standard oestrous stage-timed sequence. The oestrous stage, hormone profile (oestrogen, progesterone, progesterone/oestrogen ratio, and FSH) and lipid profile (Total cholesterol-TC, Triglycerols, High-HD and low density-LD lipid cholesterol) of the euthanised rats were determined. Resultstricosene, cyclopentadecanone 2-hydroxy-, oleic acid, and 9,17-octadecadienal, were exclusively found in HAAF and AAMF. The oestrous stage, serum hormone and lipids varied significantly (p < 0.05) between treatment groups. AAMF fraction induced sustained progesterone levels and depleted oestrogen levels, and TC and LDL were inversely related to serum oestrogen levels. DiscussionThe results suggest a depression of oestrogen and sustenance of progesterone-mediated effects, respectively, on GnRH surge. Oleic acid in AAMF may be responsible for its reproductive effects. ConclusionAAMF fraction of A. digitata (L) root bark disrupts the endocrine activity in female Wistar rats. The oleic acid component of the AAMF fraction may be responsible for modulating the activities of reproductive hormones. The authors recommend further studies to ascertain the significance of Adansonia digitata extract's oleic acid in regulating the female reproductive cycle.

Reaction of &lt;i&gt;o&lt;/i&gt;-formylbenzoic acid with hydrazides of (iso)niconitic and hydroxybenzoic acids

The reaction of nicotinic and isonicotinic acid hydrazides with o -formyl benzoic acid in ethanol led to the formation of the corresponding hydrazones. It was found that o -formyl benzoic acid reacted in aldehyde form with hydrazides to form hydrazones. When heated in acetic anhydride, the latter are smoothly cyclized into 3-acetoxyisoindoline-1-ones. Structure of the synthesized compounds was proved by 1H and 13C NMR spectroscopy data. Antiradical and antiviral activity of the synthesized hydrazones and 3-acetoxyisoindoline-1-ones was studied. A compound with a wide spectrum of virus-inhibiting action against strains of the A virus was identified.

Functional Properties of Acetylation-modified Starches of Three Purple Maize Cultivars from Côte d'Ivoire

Acetylation is one of the most used chemical modifications to improve the functional properties of starches. This allows the esterification of native starches by introducing acetyl groups into their structure. The objective of this study was to enhance the value of purple corn from Côte d'Ivoire. Some functional properties and enzymatic digestibility of acetylated and native starches of three cultivars of this maize have been determined. To this end, these maize were harvested in Katiola, a town on the Ivory Coast. The results showed that purple corn starch was modified using 10.2% acetic anhydride. Acetylated starches showed a degree of substitution and an acetyl content between 0.1 and 0.15% and 2.6 to 3.91% respectively. Acetylation increased clarity, swelling and solubility. This increase could contribute to the production of ice cream, frozen fruit, bakery products and sauces. This has also resulted in reductions in demotion trends compared to the corresponding native starches. Concerning the lowest gelling concentration, acetylated starches have recorded low values (1; 2 and 4%) which are very interesting in the food industries for infant foods. For enzymatic digestibility, the starch that has been digested much more quickly in the acetylated form is dark violet (ADP). Overall, these acetylated starches can be recommended in several food industries.

Pyrolysis acetylation: A novel on-line Py-GC-MS derivatisation for the characterisation of nitrogen-containing polymers

Several on-line chemical reactions have been combined with Py-GC-MS to improve the chromatographic behaviour of polar pyrolysis products. Derivatisations, principally methylation and silylation, have been widely employed to the analysis of oxygenated pyrolysis products, while the conversion of nitrogen-containing compounds resulted more challenging. The present study shows that amines can be efficiently converted into the corresponding N-substituted amides (acetamides) by conducting pyrolysis in the presence of acetic anhydride (PyAc). PyAc was assessed on three common N-containing polymer families, polyethylenimine (PEI, linear and branched), polyurethane (PUR, based on the methylenediphenyl diisocianate monomer) and nylons (polyamide PA6 and PA66). Upon PyAc, PEI produced a series of N-methyl, ethyl, ethenyl acetamides indicative of the formation of several alkylated monoamines that were more difficult to detect in the free form by conventional Py-GC-MS. Acetyl derivatives of linear acyclic polyamines and piperazines were also identified confirming previous investigations. In the case of PUR, the acetylated 4,4′-diaminodiphenylmethane was generated along with the diisocyanate monomer. PyAc of PA66 produced the acetyl derivative of 1,6-hexyldiamine, while the caprolactam of PA6 was only partially acetylated. The effectiveness of acetylation was confirmed by PyAc of calibration standards for microplastic analysis. Besides the acetylated amines distinctive of PUR and PA66, the acetylated forms of 1,4-butandiol from PUR and bisphenol A from polycarbonate were detected. The results showed the potential of extension of PyAc to other polymer families and highlighted some weaknesses to be solved.

Chayote Root Starch Modified with Acyl and Acetyl Groups: Synthesis, Characterization, and Preparation of Edible Films

AbstractChemical modification of starch from the chayote root (Sechium edule Jacq) is carried out with lauric acid and acetic anhydride. The modified starch is characterized by Fourier‐transform infrared spectrometry (FTIR), X‐ray diffraction (XRD), and Differential Scanning Calorimetry (DSC) and used to formulate edible films. The developed edible films are characterized based on their physicochemical and mechanical properties. The physicochemical and functional properties of starch are affected by the incorporation of the acyl and acetyl group. Both starches exhibit a significant decrease in solubility. Starch modified by the incorporation of the acyl group (lauroyl) has higher thermal stability than starch modified by the incorporation of the acetyl group. The first shows an increase in emulsifying and foaming capacity, as well as water‐ and oil‐retention capacity, while the second exhibits adequate edible film‐forming properties. The edible films develop with modified starch with acetyl group has a homogeneous surface and exhibit a higher percentage of elongation at break when they are stored at a water activity of 0.561. In accordance with the above, it is concluded that the chayote root starch modified has physicochemical and functional properties that indicate their potential utility in the food industry.

Use of Formic Acid as a CO Surrogate for the Reduction of Nitroarenes in the Presence of Dienes: A Two‐Step Synthesis of N‐Arylpyrroles via 1,2‐Oxazines

AbstractFormic acid, activated by acetic anhydride and a base, was employed as a CO surrogate to deoxygenate nitroarenes to nitrosoarenes, a reaction catalyzed by a palladium/phenanthroline complex in the homogeneous phase. Nitrosoarenes were trapped by conjugated dienes to give 3,6‐dihydro‐2H‐[1,2]‐oxazines. The latter were then transformed into N‐arylpyrroles employing CuCl as the catalyst. The reaction was designed to give the best results for pyrroles lacking any substituent in the 2 and 5 positions, which are difficult to produce employing most pyrrole syntheses.

The bidirectional extracellular electron transfer process aids iron cycling by Geoalkalibacter halelectricus in a highly saline-alkaline condition.

Bidirectional extracellular electron transfer (EET) is crucial to upholding microbial metabolism with insoluble electron acceptors or donors in anoxic environments. Investigating bidirectional EET-capable microorganisms is desired to understand the cell-cell and microbe-mineral interactions and their role in mineral cycling besides leveraging their energy generation and conversion, biosensing, and bio-battery applications. Here, we report on iron cycling by haloalkaliphilic Geoalkalibacter halelectricus via bidirectional EET under haloalkaline conditions. It efficiently reduces Fe3+ oxide (Fe2O3) to Fe0 at a 0.75 ± 0.08 mM/mgprotein/d rate linked to acetate oxidation via outward EET and oxidizes Fe0 to Fe3+ at a 0.24 ± 0.03 mM/mgprotein/d rate via inward EET to reduce fumarate. Bioelectrochemical cultivation confirmed its outward and inward EET capabilities. It produced 895 ± 23 µA/cm2 current by linking acetate oxidation to anode reduction via outward EET and reduced fumarate by drawing electrons from the cathode (‒2.5 ± 0.3 µA/cm2) via inward EET. The cyclic voltammograms of G. halelectricus biofilms revealed redox moieties with different formal potentials, suggesting the involvement of different membrane components in bidirectional EET. The cyclic voltammetry and GC-MS analysis of the cell-free spent medium revealed the lack of soluble redox mediators, suggesting direct electron transfer by G. halelecctricus in achieving bidirectional EET. By reporting on the first haloalkaliphilic bacterium capable of oxidizing and reducing insoluble Fe0 and Fe3+ oxide, respectively, this study advances the limited understanding of the metabolic capabilities of extremophiles to respire on insoluble electron acceptors or donors via bidirectional EET and invokes the possible role of G. halelectricus in iron cycling in barely studied haloalkaline environments. IMPORTANCE Bidirectional extracellular electron transfer (EET) appears to be a key microbial metabolic process in anoxic environments that are depleted in soluble electron donor and acceptor molecules. Though it is an ecologically important and applied microbial phenomenon, it has been reported with a few microorganisms, mostly from nonextreme environments. Moreover, direct electron transfer-based bidirectional EET is studied for very few microorganisms with electrodes in engineered systems and barely with the natural insoluble electron acceptor and donor molecules in anoxic conditions. This study advances the understanding of extremophilic microbial taxa capable of bidirectional EET and its role in barely investigated Fe cycling in highly saline-alkaline environments. It also offers research opportunities for understanding the membrane components involved in the bidirectional EET of G. halelectricus. The high rate of Fe3+ oxide reduction activity by G. halelectricus suggests its possible use as a biocatalyst in the anaerobic iron bioleaching process under neutral-alkaline pH conditions.

Syntrophic entanglements for propionate and acetate oxidation under thermophilic and high-ammonia conditions

Propionate is a key intermediate in anaerobic digestion processes and often accumulates in association with perturbations, such as elevated levels of ammonia. Under such conditions, syntrophic ammonia-tolerant microorganisms play a key role in propionate degradation. Despite their importance, little is known about these syntrophic microorganisms and their cross-species interactions. Here, we present metagenomes and metatranscriptomic data for novel thermophilic and ammonia-tolerant syntrophic bacteria and the partner methanogens enriched in propionate-fed reactors. A metagenome for a novel bacterium for which we propose the provisional name ‘Candidatus Thermosyntrophopropionicum ammoniitolerans’ was recovered, together with mapping of its highly expressed methylmalonyl-CoA pathway for syntrophic propionate degradation. Acetate was degraded by a novel thermophilic syntrophic acetate-oxidising candidate bacterium. Electron removal associated with syntrophic propionate and acetate oxidation was mediated by the hydrogen/formate-utilising methanogens Methanoculleus sp. and Methanothermobacter sp., with the latter observed to be critical for efficient propionate degradation. Similar dependence on Methanothermobacter was not seen for acetate degradation. Expression-based analyses indicated use of both H2 and formate for electron transfer, including cross-species reciprocation with sulphuric compounds and microbial nanotube-mediated interspecies interactions. Batch cultivation demonstrated degradation rates of up to 0.16 g propionate L−1 day−1 at hydrogen partial pressure 4–30 Pa and available energy was around −20 mol−1 propionate. These observations outline the multiple syntrophic interactions required for propionate oxidation and represent a first step in increasing knowledge of acid accumulation in high-ammonia biogas production systems.

Synthesis and Evaluation of Acetylcholinesterase Inhibitory and Cytotoxic Activities of Pyrano[2,3-d]pyrimidines

Objective: The study was conducted to evaluate the in vitro acetylcholinesterase (AchE) inhibition activity of novel pyrano[2,3- d]pyrimidine derivatives. Methods: A series of new pyrano[2,3- d]pyrimidine derivatives were synthesized in moderate to good yields (63%-81%) by using microwave-prompted “one-pot” two-step multicomponent reactions of cyclohexane-1,3-dione, malononitrile, aldehydes, and acetic anhydride. Noticeably, Diazabicyclo[2.2.2]octane was successfully employed as a basic catalyst for the formation of 2-amino-4H-pyran-3-carbonitrile intermediates. These products were identified using spectral data, and assessed in terms of their AChE inhibition activity and cytotoxicity against three types of human cancer cell lines including epidermoid carcinoma (KB), hepatoma carcinoma (HepG2), and non-small lung cancer (A549) cell lines. Results: Most of the products depicted moderate to good AChE inhibitory activity, among them, one product with methoxy moiety at meta-position on phenyl group showed the best AchE inhibition activity with IC50 values of 2.20 ± 0.17 µg/mL. Moreover, products exhibited no cytotoxicity against cancer cell lines. Conclusion: This study highlighted that pyrano[2,3- d]pyrimidine derivatives as promising candidates for further investigations directed to the discovery of new AChE inhibitors which could be used in Alzheimer's disease therapy.

Validation of 16S rRNA gene sequencing and metagenomics for evaluating microbial immigration in a methanogenic bioreactor.

To quantitatively evaluate the impact of microbial immigration from an upstream community on the microbial assembly of a downstream community, an ecological genomics (ecogenomics)-based mass balance (EGMB) model coupled with 16S rRNA gene sequencing was previously developed. In this study, a mock community was used to further validate the EGMB models and demonstrate the feasibility of using metagenome-based EGMB model to reveal both microbial activity and function. The mock community consisting of Aeromonas, Escherichia, and Pseudomonas was fed into a lab-scale methanogenic bioreactor together with dissolved organic substrate. Using qPCR, 16S rRNA gene, 16S rRNA gene copy number normalization (GCN), and metagenome, results showed highly comparable community profiles in the feed. In the bioreactor, Aeromonas and Pseudomonas exhibited negative growth rates throughout the experiment by all approaches. Escherichia's growth rate was negative by most biomarkers but was slightly positive by 16S rRNA gene. Still, all approaches showed a decreasing trend toward negative in the growth rate of Escherichia as reactor operation time increased. Uncultivated populations of phyla Desulfobacterota, Chloroflexi, Actinobacteriota, and Spirochaetota were observed to increase in abundance, suggesting their contribution in degrading the feed biomass. Based on metabolic reconstruction of metagenomes, these populations possessed functions of hydrolysis, fermentation, fatty acid degradation, or acetate oxidation. Overall results supported the application of both 16S rRNA gene- and metagenome-based EGMB models to measure the growth rate of microbes in the bioreactor, and the latter had advantage in providing insights into the microbial functions of uncultivated populations.

Synthesis, Computational Study of β-lactam Derivatives Bearing Quinazoline Schiff Bases as Anthelmintics

Background: Infections caused by parasites continue to pose a risk to both human and animal health. The most popular drug classes for treating these infections include thiabendazole, imidazothiazoles, levamisole, and avermectins (obtained from the fermentation products of Streptomyces avermitilis). The majority of bacteria that we come across in any form of infection are successfully combatted by β- lactam medicines. Similar to the majority of treatments, problems with treatment resistance to these drugs have evolved over time, necessitating the development of new anthelmintic medications. This study aims to investigate a series of quinazoline-bearing β-lactam rings as potent anthelmintic agents. Methods: The new series of quinazoline bearing β-lactam was synthesized via reaction of 5-bromo anthranilic acid with acetic anhydride to produce 6-bromo-2-methyl-4H-benzo (1,3) oxazin-4-one which was then converted into 3-amino-6-bromo-2-methylquinazolin-4(3H)-one by the reaction of hydrazine hydrate in the presence of anhydrous pyridine. The resultant intermediate then goes through a Schiff reaction with various aromatic aldehydes, followed by reflux with triethylamine and chloroacetyl chloride. Results: Structural assignments of these compounds have been made by elemental analysis, FTIR,1HNMR and Mass spectral data and the purity of the compounds was determined by TLC. Molecular docking studies showed the effective binding of synthesized derivatives with tubulin in comparison to the orientation of standard drugs. The anthelmintic activities of all the synthesized compounds were evaluated separately for their possible using common Indian earthworm Pheritima posthuma. Conclusion: A total of ten derivatives of quinazoline bearing β-lactam ring were designed, synthesized and evaluated against the Indian earthworm Pheritima posthuma. Out of ten derivatives, SQD2 and SQD6, showed promising anthelmintic activity when compared with standard drugs albendazole and piperazine citrate.

Synthesis of 3-(3,4-diacetoxyphenyl)acrylic acid and 4-(oxo-3-(piperidin-1-yl)pro-1-en-1-yl)-1,2-phenylendiacetate from 3-(3,4-dihydroxyphenyl)acrylic acid and their toxicity test by Brine Shrimp Lethality Test method

Derivatization 3-(3,4-dihydroxyphenyl)acrylic acid to 3-(3,4-diacetoxyphenyl)acrylic acid (1) and 4-(oxo-3-(piperidin-1-yl)pro-1-en-1-yl)-1,2-phenylendiacetate (3) and its toxicity test has been successfully carried out. Derivatization was carried out through acetylation, chlorination, and amidation reactions. The acetylation reaction was carried out using acetic anhydride in pyridine solvent at room temperature for 4 hours to produce compound 1 as a white amorphous solid with m.p. 181-183oC and yield of 85.68%. The chlorination reaction was carried out using thionyl chloride in toluene solvent at the reflux temperature of 79°C for 4 hours and continued with in situ amidation using piperidine in dichloromethane solvent at room temperature to produce compound 3 as a white crystal with m.p. 139-141oC and yield of 39.45%. The toxicity test of the two compounds against Artemia salina Leach shrimp larvae using probit analysis showed that compounds 1 and 3 were toxic with LC50 values ​​of 8.919 μg/mL and 84.511 μg/mL, respectively. This data shows that the acetylation of 3-(3,4-dihydroxyphenyl)acrylic acid compound (LC50 = 46.50 μg/mL) increases the toxicity to larvae of Artemia salina Leach shrimp.&#x0D; &#x0D; Keywords: 3-(3,4-dihydroxyphenyl)acrylic acid, 3-(3,4-diacetoxyphenyl)acrylic acid, 4-(oxo-3-(piperidin-1-yl)pro-1-en-1-yl)-1,2-phenylendiacetate, Artemia salina Leach.

Effect of pendant ester groups on gas transport property of 6FDA-BAPP/6FAP copolyimide membrane

Despite the various methods that have been developed, controlling the microstructure of polyimide membranes to achieve excellent separation performance based on target gases remains a challenge. One such method involves rearranging polyimides containing ortho-hydroxyl groups into polybenzoxazoles at temperatures above 400 °C, which can effectively distort the backbones and improve gas diffusion. However, this approach is limited by the extremely high conversion temperatures required and low conversion degrees achieved. The esterification process of the polyimide, which contains ortho-hydroxyl groups to the imide ring, represents a simple and effective approach to enhance the membrane's competitiveness in gas separation without undergoing thermal rearrangement at high temperatures. The polyimide was prepared by the polycondensation of 4,4'-(Hexafluoro isopropylidene) diphthalic anhydride (6FDA), 2,2-double (4,4-amino phenoxy) propane (BAPP), and 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (6FAP). Microstructures and gas transport coefficients were analyzed when the esterification of 6FDA-BAPP/6FAP was conducted using acetic anhydride and caproic anhydride. In CO2/N2 separation, a-6FDA-BAPP/6FAP exhibits CO2 permeability of 1279.41 ± 66.93 Barrer and perm-selectivity of 40.80 ± 2.27, owing to the significantly improved affinity to CO2. The membrane of c-6FDA-BAPP/6FAP exhibit the further improved CO2 permeability and deteriorated perm-selectivity, due to a leveling effect on the diffusion of CO2 and N2 caused by the pendant caproates with longer alkyl chains. The results confirmed that the gas separation performance of polyimide membrane containing ortho-hydroxyl groups is sensitive to the pendant group.

Biochar establishing syntrophic partnership between exoelectrogens to facilitate extracellular electron transfer

Biochar was regarded as a promising accelerator for extracellular electron transfer (EET), while the mechanism of biochar facilitating electricity harvest in bioelectrochemical system (BES) was in debates. In this study, sawdust-based biochar with low conductivity but strong redox-based electron exchange capacity was added into BES with two forms, including a suspended form (S-BC) added in anode chamber and a fixed form closely wrapping up the anode (F-BC). Compared with the control group, S-BC and F-BC addition dramatically increased accumulated electricity output by 2.0 and 5.1 times. However, electrochemical analysis characterized the lowest electrochemical property on anode surface in F-BC modified group. A 2nd period conducted by separating F-BC modified group with “aged F-BC + new anode” group and “single aged anode” group demonstrated that F-BC contributed >95 % to the current generation of F-BC modified group, while the anode almost acted as a conductor to transfer the generated electrons to cathode. Microbial community analysis revealed that both heterotrophic and autotrophic exoelectrogens contributed to current generation. The presence of biochar upregulated functional genes encoding cytochrome-c and type IV pilus, thereby boosting electricity harvest efficiency. Interestingly, the heterotrophic exoelectrogens of Geobacter/Desulfovibrio tended to attach on fixed surfaces of both biochar and anode, and the autotrophic exelectrogen of Hydrogenophaga was selectively enriched on biochar surfaces whatever fixed or suspended form. Consequently, a syntrophic partnership between Geobacter/Desulfovibrio and Hydrogenophaga was potentially establishment on F-BC surface for highly-efficient electricity harvest. In this syntrophic EET model, biochar potentially acted as the redox-active mediator, which temporarily accepted electron released by Geobacter/Desulfovibrio via acetate oxidation, and then donated them to Hydrogenophaga attached on biochar surfaces for autotrophic EET. This was distinct from a regular EET conducted by heterotrophic exoelectrogens. These findings provided new insights to understand the mechanisms of biochar facilitating EET by syntrophic metabolism pathway.

Mineral transformation of poorly crystalline ferrihydrite to hematite and goethite facilitated by an acclimated microbial consortium in electrodes of soil microbial fuel cells

In this study, we investigated the biogenic mineral transformation of poorly crystalline ferrihydrite in the presence of an acclimated microbial consortium after confirming successful soil microbial fuel cell optimization. The acclimated microbial consortia in the electrodes distinctly transformed amorphous ferrihydrite into crystallized hematite (cathode) and goethite (anode) under ambient culture conditions (30 °C). Serial analysis, including transmission/scanning electron microscopy and X-ray/selected area electron diffraction, confirmed that the biogenically synthesized nanostructures were iron nanospheres (~100 nm) for hematite and nanostars (~300 nm) for goethite. Fe(II) ion production with acetate oxidation via anaerobic respiration was much higher in the anode electrode sample (3.2- to 17.8-fold) than for the cathode electrode or soil samples. Regarding the culturable bacteria from the acclimated microbial consortium, the microbial isolates were more abundant and diverse at the anode. These results provide new insights into the biogeochemistry of iron minerals and microbial fuel cells in a soil environment, along with physiological characters of microbes (i.e., iron-reducing bacteria), for in situ applications in sustainable energy research.

Recyclability and catalytic characteristics of copper oxide nanoparticles derived from bougainvillea plant flower extract for biomedical application

Abstract This work aims to investigate the environmentally sustainable technique to synthesize the copper nanoparticles using bougainvillea flower ethanolic extract at ambient temperature. Copper nanoparticles have considerable potential for reducing the environment’s harmful pigments and nitrogen contaminants. The oxidized copper nanoscale catalysts are enclosed inside nanomaterial, which work as a benign and sustainable resource for capping agents. Ultraviolet spectroscopic, transmission electron microscopy (TEM), and X-ray crystallography (XRD) techniques were used to evaluate the produced oxidized copper nanocrystals. The particles produced have been very robust, are cylindrical in form, and have an outer diameter of 12 nm. Furthermore, under normal conditions, copper oxide (CuO) nanomaterials demonstrated strong photocatalytic efficiency in liquid media for the oxidation of Congo red, bromothymol blue, and 4-nitrophenol in an acidic solution acetic anhydride. Moreover, the CuO nanocrystalline enzyme could be readily vortexed or used for five cycles with an exchange rate of even over 90%. The evaporation process caused around 18% of the loss of weight between 25°C and 190°C, while soil organic breakdown caused almost 31% of the loss of weight around 700°C. As a result, the little reduction in enzymatic effectiveness of the recoverable multilayer CuO substrate might be attributed to catalytic degradation throughout spinning and processing.

A protocol based on solid phase microextraction -gas chromatography-tandem mass spectrometry for the monitoring of parabens and bisphenols in human saliva

The herein presented work aims to the development of an easy method for the quantitative determination of parabens and bisphenols in human salivabased on the use of methyl chloroformate as a derivatizing agent, followed by solid-phase microextraction (SPME) and gas chromatography-triple quadrupole mass spectrometry (GC-QqQ-MS) analysis with selected reaction monitoring (SRM). Using multivariate analysis, two derivatization strategies were compared and optimized, demonstrating that the use of methyl chloroformate led to better sensitivity than the classical derivatization by acetic anhydride. Good performance in the sorption process of the derivatized target analytes was obtained using the most recent commercialized overcoated fiber (PDMS/DVB/PDMS). The validation procedure of the final protocol led to satisfactory results in terms of linearity, limit of quantitation, accuracy, and precision. All parabens were quantified from 10 ng/L using the developed method, except for methylparaben, which was quantified from 100 ng/L along with all bisphenols. Intra- and inter-day accuracy and intra- and inter-day precision can be considered satisfactory for all analytes (values between 73% and 118%), except for the inter-day accuracy of BPF. Quite good results also in terms of matrix effect were obtained for the target compounds (range 71% to 118%, RSD% less than 13.6%), except for BPA at the middle concentration and MeP at the lowest concentration. The greenness of the method was evaluated and the results indicated that our approach is more eco-friendly than previously published methods. Based on its characteristics, the presented method can be considered a suitable approach to determine parabens and bisphenols in routine analysis for biomonitoring purposes.

Determination of Tilmicosin in Poultry and Pork Meat by a Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) Preparation Method and Gas Chromatography–Tandem Mass Spectrometry (GC–MS/MS)

This paper presents a novel and reliable approach for the determination of tilmicosin residues in poultry muscle and pork via gas chromatography–tandem mass spectrometry after precolumn derivatization. The samples were subjected to a quick, easy, cheap, effective, rugged, and safe preparation method, solid-phase extraction, hydrogenation, gel chromatography separation, acid hydrolysis, and derivatization with pyridine and acetic anhydride. For the blank spiked samples at the limit of quantification, 0.5 times the maximum residue limit (MRL), the MRL, and 2.0 times the MRL, the recoveries were from 76.91 to 87.99% with a precision of 2.04–5.47%. The limits of detection and quantification were 2.3–4.4 and 6.2–9.8 µg kg−1, respectively. The protocol was validated and real samples analyzed to demonstrate its practical application.

Degradation of Sodium Acetate by Catalytic Ozonation Coupled with a Mn-Functionalized Fly Ash: Reaction Parameters and Mechanism.

Supported ozone catalysts usually take alumina, activated carbon, mesoporous molecular sieve, graphene, etc. as the carrier for loading metal oxide via the impregnation method, sol-gel method and precipitation method. In this work, a Mn-modified fly ash catalyst was synthesized to reduce the consumption and high unit price of traditional catalyst carriers like alumina. As a solid waste discharged from coal-fired power plants fueled by coal, fly ash also has porous spherical fine particles with constant surface area and activity, abd is expected to be applied as the main component in the synthesis of ozone catalyst. After the pretreatment process and modification with MnOx, the obtained Mn-modified fly ash exhibited stronger specific surface area and porosity combined with considerable ozone catalytic performance. We used sodium acetate as the contaminant probe, which is difficult to directly decompose with ozone as the end product of ozone oxidation, to evaluate the performance of this Mn-modified fly. It was found that ozone molecules can be transformed to generate ·OH, ·O2- and 1O2 for the further oxidation of sodium acetate. The oxygen vacancy produced via Mn modification plays a crucial role in the adsorption and excitation of ozone. This work demonstrates that fly ash, as an industrial waste, can be synthesized as a potential industrial catalyst with stable physical and chemical properties, a simple preparation method and low costs.

Nickel-catalyzed Nucleophilic C-Borylation of Imines.

Application of bioisostere plays an important role in drug discovery. α-Aminoboronic acid is the familiar bioisostere of α-amino acid. Developing reactions for the synthesis of a wide variety of α-aminoboronic acid is one important task for synthetic chemistry. Herein, we report the development of nucleophilic C-borylation chemistry for N-arylimines catalyzed by nickel. The reaction proceeds through the insertion of a borylnickel species into the C=N bond to afford the corresponding α-aminoboronate, which was isolated as acetamide after trapping with acetic anhydride. N-Benzyl imine is also tolerated by the developed reaction.