An effective magnetic nanobiocomposite: Preparation, characterization and its application for adsorption removal of P-nitroaniline from aquatic environments.

In this investigation, a magnetic nanobiocomposite, denoted as CoFe2O4/Activated Carbon integrated with Chitosan (CoFe2O4/AC@Ch), was synthesized based on a microwave-assisted for the efficacious adsorption of P-nitroaniline (PNA). The physicochemical properties of the said nano biocomposite were thoroughly characterized using a suite of analytical methodologies, namely FESEM/EDS, BET, FTIR, XRD, and VSM. The results confirm the successful synthesis of the nanobiocomposite, with its point of zero charge (pHZPC) determined to be 6.4. Adsorptive performance towards PNA was systematically examined over a spectrum of conditions, encompassing variations in PNA concentration (spanning 10-40 mg/L), adsorbent concentration (10-200 mg/L), contact periods (2.5-22.5 min), and solution pH (3-11). Upon optimization, the conditions converged to an adsorbent concentration of 200 mg/L, pH 5, PNA concentration of 10 mg/L, and a contact duration of 22.5 min, under which an impressive PNA adsorption efficacy of 98.6% was attained. Kinetic and isotherm analyses insinuated the adsorption mechanism to adhere predominantly to the pseudo-second-order kinetic and Langmuir isotherm models. The magnetic nanocomposite was recovered and used in 4 cycles, and the absorption rate reached 86%, which shows the good stability of the magnetic nanocomposite in wastewater treatment. Conclusively, these empirical outcomes underscore the viability of the formulated magnetic nanobiocomposite as a potent, recyclable adsorbent for the proficient extraction of PNA from aqueous matrices.

A double-emission molecularly imprinted ratiometric fluorescent sensor based on carbon quantum dots and fluorescein isothiocyanate for visual detection of p-nitroaniline.

A novel molecularly imprinted ratiometric fluorescent sensor CQDs@MIP/FITC@SiO2 for the detection of p-nitroaniline (p-NA) was constructed through the mixture of CQDs@MIP and FITC@SiO2 in the ratio of 1:1 (VCQDs@MIP:VFITC@SiO2). The polymers of CQDs@MIP and FITC@SiO2 were prepared by sol-gel method and reversed-phase microemulsion method, respectively. CQDs@MIP was used as the auxiliary response signal and FITC@SiO2 was used as the reference enhancement signal. The signal was measured at excitation/emission wavelengths of 365/438, 512 nm. The sensor showed good linearity in the concentration range 0.14-40.00 µM (R2 = 0.998) with a detection limit of 0.042 µM for p-NA. The color change of "blue-cyan-green" could be observed by the naked eye under 365 nm UV light, thus realizing the visual detection of p-NA. The sensor presented comparable results compared with high-performance liquid chromatography (HPLC) method for the detection of p-NA in hair dye paste and aqueous samples with recoveries of 96.8-103.7% and 95.8-104.4%, respectively. It was demonstrated that the constructed sensor possesses the advantages of simplicity, excellent selectivity, superior sensitivity, and outstanding stability.

Novel Small Molecule Matrix Screening for Simultaneous MALDI Mass Spectrometry Imaging of Multiple Lipids and Phytohormones.

Most of the traditional matrices cannot simultaneously image multiple lipids and phytohormones, so screening and discovery of novel matrices stand as essential approaches for broadening the application scope of matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI). In this work, 12 organic small molecule compounds were comprehensively screened and investigated as potential MALDI matrices for simultaneous imaging analysis of various lipids and phytohormones. In the positive ionization mode, p-nitroaniline, m-nitroaniline, and 2-aminoterephthalic acid displayed good performance for the highly sensitive detection of lysophosphatidylcholines (LPCs), phosphatidylcholines (PCs), and triacylglycerols (TGs). Furthermore, p-nitroaniline possessed excellent characteristics of strong ultraviolet absorption and homogeneous cocrystallization, making it a desirable matrix for MALDI-MSI analysis of eight plant hormones. Compared with conventional matrices (2,5-dihydroxybenzoic acid (DHB), α-cyano-4-hydroxycinnamic acid (CHCA), and 9-aminoacridine (9-AA), the use of p-nitroaniline resulted in higher ionization efficiency, superior sensitivity, and clearer imaging images in dual polarity mode. Our research offers valuable guidance and new ideas for future endeavors in matrix screening.

Efficient Removal of Hazardous P-Nitroaniline from Wastewater by Using Surface-Activated and Modified Multiwalled Carbon Nanotubes with Mesostructure.

P-nitroaniline (PNA) is an aniline compound with high toxicity and can cause serious harm to aquatic animals and plants. Multiwalled carbon nanotubes (MWCNTs) are a multifunctional carbon-based material that can be applied in energy storage and biochemistry applications and semiconductors as well as for various environmental purposes. In the present study, MWCNTs (CO2-MWCNTs and KOH-MWCNTs) were obtained through CO2 and KOH activation. ACID-MWCNTs were obtained through surface treatment with an H2SO4-HNO3 mixture. Herein, we report, for the first time, the various MWCNTs that were employed as nanoadsorbents to remove PNA from aqueous solution. The MWCNTs had nanowire-like features and different tube lengths. The nanotubular structures were not destroyed after being activated. The KOH-MWCNTs, CO2-MWCNTs, and ACID-MWCNTs had surface areas of 487, 484, and 80 m2/g, respectively, and pore volumes of 1.432, 1.321, and 0.871 cm3/g, respectively. The activated MWCNTs contained C-O functional groups, which facilitate PNA adsorption. To determine the maximum adsorption capacity of the MWCNTs, the influences of several adsorption factors-contact time, solution pH, stirring speed, and amount of adsorbent-on PNA adsorption were investigated. The KOH-MWCNTs had the highest adsorption capacity, followed by the CO2-MWCNTs, pristine MWCNTs, and ACID-MWCNTs. The KOH-MWCNTs exhibited rapid PNA adsorption (>85% within the first 5 min) and high adsorption capacity (171.3 mg/g). Adsorption isotherms and kinetics models were employed to investigate the adsorption mechanism. The results of reutilization experiments revealed that the MWCNTs retained high adsorption capacity after five cycles. The surface-activated and modified MWCNTs synthesized in this study can effectively remove hazardous pollutants from wastewater and may have additional uses.

Absorption spectra of p-nitroaniline derivatives: charge transfer effects and the role of substituents.

CONTEXT: Push-pull compounds are model systems and have numerous applications. By changing their substituents, properties are modified and new molecules for different applications can be designed. The work investigates the gas-phase electronic absorption spectra of 15 derivatives of push-pull para-nitroaniline (pNA). This molecule has applications in pharmaceuticals, azo dyes, corrosion inhibitors, and optoelectronics. Both electron-donor and electron-withdrawing groups were investigated. Employing machine learning-derived Hammett's constants σm, σm0, σR, and σI, correlations between substituents and electronic properties were obtained. Overall, the σm0 constants presented the best correlation with HOMO and LUMO energies, whereas the σR constants best agreed with the transition energy of the first band and HOMO-LUMO energy gap. Electron-donors, which have lower σR values, redshift the absorption spectrum and reduce the HOMO-LUMO energy gap. Conversely, electron-withdrawing groups (higher σR's) blueshift the spectrum and increase the energy gap. The second band maximum energies, studied here for the first time, showed no correlation with σ but tended to increase with σ. A comprehensive charge transfer (CT) analysis of the main transition of all systems was also carried out. We found that donors (lower σ's) slightly enhance the CT character of the unsubstituted pNA, whereas acceptors (higher σ's) decrease it, leading to increased local excitations within the aromatic ring. The overall CT variation is not large, except for pNA-SO2H, which considerably decreases the total CT value. We found that the strong electron donors pNA-OH, pNA-OCH3, and pNA-NH2, which have the smallest HOMO-LUMO energy gaps and lowest σ's, have potential for optoelectronic applications. The results show that none of the studied molecules is fluorescent in the gas phase. However, pNA-NH2 and pNA-COOH in cyclohexane and water reveal fluorescence upon solvation. METHODS: We investigated theoretically employing the second-order algebraic diagrammatic construction (ADC(2)) ab initio wave function and time-dependent density functional theory (TDDFT) the gas-phase electronic absorption spectra of 15 derivatives of p-nitroaniline (pNA). The investigated substituents include both electron-donor (C6H5, CCH, CH3, NH2, OCH3, and OH,) and electron-withdrawing (Br, CCl3, CF3, Cl, CN, COOH, F, NO2, and SO2H) substituents.

Smartphone-enabled colorimetric visual quantification of highly hazardous trivalent chromium ions in environmental waters and catalytic reduction of p-nitroaniline by thiol-functionalized gold nanoparticles.

High-efficiency sensing systems for extremely hazardous chromium (Cr(III)) ions are important due to their detrimental effects on human health and the environment. We employed a spectrophotometric method combined with a smartphone (red, green, and blue (RGB) color ratio)-based detection platform to realize the quick, visually quantifiable in situ detection of Cr(III) ions using surface plasmon resonance (SPR)-aided colorimetry. For optical sensing nanoprobes, we synthesized the 2-Mercapto-5-methyl-1,3,4-thiadiazole (MMT)-modified gold nanoparticles (MMT-AuNPs) using a wet chemical method. By way of a coordination reaction, the Cr(III) ions induce the as-prepared MMT-AuNPs to aggregate and subsequently change the SPR wavelength band. The freshly synthesized MMT-AuNPs exhibited a wine-red color. While Cr(III) ions interact with the MMT-AuNPs, the color of the latter evolved from wine red to purple, thus facilitating visual monitoring. The SPR-relevant color change allowed the quantitative sensing of Cr(III) ions in the range of 40-128 nM, with the limit of detection of 6.93 nM when employing the spectrophotometric method and 12.4 nM when using the smartphone RGB color ratio. Furthermore, we developed the spectrophotometric technique that used the smartphone RGB color ratio for on-site analysis of Cr(III) ions in environmental water samples, indicating the possibility of its chemo-sensing applications for portable quantitative detection devices. Additionally, the catalytic performance of the MMT-AuNPs was demonstrated by the reduction of p-nitroaniline in the presence of sodium borohydride. It was interestingly unveiled that the MMT-AuNPs showed outstanding catalytic performance with a catalytic rate constant of 6.31 × 10-3 s-1.

Reduction of Nitroaromatics by Gold Nanoparticles on Porous Silicon Fabricated Using Metal-Assisted Chemical Etching.

In this study, we investigated the use of porous silicon (PSi) fabricated using metal-assisted chemical etching (MACE) as a substrate for the deposition of Au nanoparticles (NPs) for the reduction of nitroaromatic compounds. PSi provides a high surface area for the deposition of Au NPs, and MACE allows for the fabrication of a well-defined porous structure in a single step. We used the reduction of p-nitroaniline as a model reaction to evaluate the catalytic activity of Au NPs on PSi. The results indicate that the Au NPs on the PSi exhibited excellent catalytic activity, which was affected by the etching time. Overall, our results highlighted the potential of PSi fabricated using MACE as a substrate for the deposition of metal NPs for catalytic applications.

Biotransformation of nitro aromatic amines in artificial alkaline habitat by pseudomonas DL17.

Nitro-aromatics are listed in carcinogenic, teratogenic, and mutagenic compounds list. p- nitro-aniline is one of them used as a precursor of various chemical compounds in many industries like dyes, drugs, paints and several others. These are mostly given out as an effluent in rivers, lakes or open passage of land which exert several hazards to living creatures and environment. Some of the organic compounds are stable in alkaline condition and persist longer in environment. Very few reports are elaborating bio-remediation in alkaline condition using different hydrocarbons. This study was planned to elaborate mechanism of detoxification and searching the potential of decontamination of p-nitro-aniline in alkaline condition by experimental microbial strain. The bacterial strain pseudomonas DL17 was isolated from alkaline Lake Lonar, Buldana, (MS.) India; and employed in this experiment considering its indigenous property to tolerate the alkaline pH. It also showed resistance to p-nitro-aniline with its raising concentrations on testing after adaptation. The experimental microbial stain showed 100% biodegradation of (500 mg/L) p-nitro-aniline within 48h. On shaking incubator with 110 rpm and at 32 °C optimum temperature. The centrifugate obtained after spinning at 10,000 g by cold centrifuge was used for solvent extraction. Generally, ethyl acetate or DCM was used for solvent extraction. The estimation of residual remains of p-nitro aniline by 6h. intervals was carried after removal of flasks from shaking incubator and centrifugation. At the optimum temperature and pH experiments were carried after knowing the resistance to experimental contaminant range (100-400 mg/L) of p-nitro aniline one month and further extended to 500 mg/L for 15days more. The residual metabolites were purified by column chromatography and various spectrometric studies such as UV-Vis spectroscopy, HNMR, FTIR and GCMS revealed that p-Phenylenediamine, acetanilide, aniline, acetaminophen, catechol, p-bezoquinone, cis-cis muconate as a metabolites. On the basis of the metabolites isolated and characterized by different spectroscopic studies the bio-catalytic mechanism was deduced. The induced enzymes such as nitroreductase, catalase, peroxidase, acetanilide hydroxylase, super oxide dismutase, catechol 1, 2 dioxygenase, catechol 2, 3 dioxygenase has commercial importance in biochemical industries. Induction of such biotransformation enzymes and consumption of p-nitro aniline concentration in experiments makes sure that this microbial strain pseudomonas DL17 can be employed for decontamination of nitro aniline polluted sites as well as isolation of such metabolites characterized and enzymes studied.

Coupling of (methane + air)-membrane biofilms and air-membrane biofilms: Treatment of p-nitroaniline wastewater.

Membrane biofilm (MBf) technology is a promising biological water treatment process that combines membrane aeration with biofilms. To expand its application in the treatment of toxic organic wastewater, methane/air gas mixture-MBfs ((CH4 + Air)-MBfs) and air-MBfs were coupled to enhance the treatment of p-nitroaniline (PNA) wastewater. Based on exploration of the membrane permeability of methane and oxygen, a hybrid MBf reactor was constructed, and the degradation characteristics of PNA and the coupling effects of (CH4 + Air)-MBfs and air-MBfs were studied. The permeation flux of methane was found to be 1.114 g/(m2 d) when using a methane/air gas mixture at an aeration pressure of 10 kPa, and this result was better than that when methane was used as the aeration gas alone. Aeration with a methane/air gas mixture provided conditions for realizing aerobic methane oxidation; the aerobic methane oxidation that occurred in the (CH4 + Air)-MBfs promoted the reduction of PNA, and the intermediates of PNA degradation were further degraded by the air-MBfs. At an influent PNA membrane area load of 1.67 g/(m2 d), the PNA removal load reached 187.30 g/(m3 d). The coupling of MBfs took advantage of different matrix-based MBfs and promoted the degradation of PNA by utilizing the synergistic effects of various functional microorganisms.

A novel high-yield synthesis of aminoacyl p-nitroanilines and aminoacyl 7-amino-4-methylcoumarins: Important synthons for the synthesis of chromogenic/fluorogenic protease substrates.

Aminoacyl p-nitroaniline (aminoacyl-pNA) and aminoacyl 7-amino-4-methylcoumarin (aminoacyl-AMC) are important synthons for the synthesis of chromogenic/fluorogenic protease substrates. A new efficient method was developed to synthesize aminoacyl-pNA and aminoacyl-AMC derivatives in excellent yields starting from either amino acids or their corresponding commercially available N-hydroxysuccinimide esters. The method involved the in situ formation of selenocarboxylate intermediate of protected amino acids and the subsequent non-nucleophilic amidation with an azide. Common protecting groups used in amino acid/peptide chemistry were all well-tolerated. The method was also successfully applied to the synthesis of a dipeptide conjugate, indicating that the methodology is applicable to the synthesis of chromogenic substrates containing short peptides. The method has general applicability to the synthesis of chromogenic and fluorogenic peptide substrates and represents a convenient and high-yield synthesis of N(α)-protected-aminoacyl-pNAs/AMCs, providing easy access to these important synthons for the construction of chromogenic/fluorogenic protease substrates through fragment condensation or stepwise elongation.

Recent progress in controlling the synthesis and assembly of nanostructures: Application for electrochemical determination of p-nitroaniline in water.

The development of nanoparticle research has grown considerably in recent years. One of the reasons for the considerable current interest in nanoparticles is because such materials frequently display unusual physical (structural, electronic, magnetic, and optical) and chemical (catalytic) properties. The development of nanomaterials is of interest to the scientific community and industrial companies. Different methods (physical, chemical, and biological) allow their manufacture. In particular, a major effort has been devoted to the development and improvement of synthesis methods in order to obtain nano-objects of controlled size and shape, a necessary pre-requisite to their organization, and to the study of their intrinsic and collective properties. Reviews play an important role in keeping interested parties up to date on the current state of the research in any academic field. This review aims to focus on the development of nanoparticles and stabilization with adsorbed/covalently attached ligands in solution phase since these factors are deeply related to the origins of the particles' stability, the media to which they are exposed, and the involved applications. This study also examines the factors that influence the synthesis of nanoparticles. It aims to provide an overview of existing electrochemical sensors, particularly those that operate with nanomaterial-based electrode modifications for p-nitroaniline (PNA) determination and to propose guidelines for related research and development activities. Emphasis was placed on the procedure for the analysis of PNA in water samples using nanosilver-based electrodes.

Cucurbit[6]uril modified CdTe quantum dots fluorescent probe and its selective analysis of p-nitroaniline in environmental samples.

An efficient fluorescent probe based on cucurbit[6]uril modified CdTe quantum dots (CB[6]@QDs) was prepared. This novel probe showed significant and selective fluorescence quenching and complexation capacity to p-nitroaniline, its interaction mechanism was studied by both experimental and theoretical methods. Furthermore, a fluorescent method was developed for the determination of p-nitroaniline in different environmental samples. The fluorescence intensity of CB[6]@QDs showed a good linearity response to p-nitroaniline in the concentration range of 2.5 × 10-7-3.0 × 10-6 mol/L with a correlation coefficient (R2) of 0.9976, the limit of detection (LOD) was 6 × 10-8 mol/L and the limit of quantification (LOQ) was 2 × 10-7 mol/L. Moreover, about 0-1.5 × 10-6 mol/L p-nitroaniline were determined in environmental samples, the recoveries were in the range of 88-109% with the relative standard deviations (n = 3) of 1.2-4.5%. Compared with previous fluorescent methods, the present method shortened and simplified the sample pretreatment as well as enhanced the sensitivity and selectivity of analytical method. No further sample pretreatment procedure is needed and the LOD of present method was one order of magnitude less than previous fluorescent methods, showed it is a simple, selective and sensitive method.

Design of a chromogenic substrate for elastase based on split GFP system-Proof of concept for colour switch sensors.

Recent studies have demonstrated that human neutrophil elastase (HNE) can be used as marker for inflammation/infection of chronic wounds since it was found to be present in high concentration in exudate collected from chronic wounds. Biosensors used in wound care benefit from a chromogenic signalling due to the readiness of signal interpretation, but the most common use faint yellow chromogenic molecules such as p-nitroaniline (pNa). In addition, if to be converted into smart dressings, the colour of the detection system should not be masked by the exudate's colour. In this work, we designed a chromogenic substrate for HNE aiming to be incorporated in a smart dressing as a colour switch sensor. The substrate was developed using the GFP-like chromoprotein ultramarine (UM), following the split GFP technology. The cleavage sequence for HNE (Ala-Ala-Pro-Val) was embedded into the sensing moiety of the substrate corresponding to the 11th ß-sheet. In the presence of HNE, the 11th ß-sheet is able to interact to the signalling moiety composed of the ß1-ß10 incomplete barrel, allowing the re-establishment of the chromophore environment and, hence, the colour production. Structural homology and molecular dynamics simulations were conducted to aid on the disclosure of the structural changes that are the base of the mechanism of action of this HNE switch substrate. Our findings explore the possible application of GFP-like chromogenic sensors in point-of-care devices for the evaluation of the wounds status, representing a major step in the medical field.

Rapid and reliable determination of p-nitroaniline in wastewater by molecularly imprinted fluorescent polymeric ionic liquid microspheres.

Rapid and efficient detecting trace amount of environmental p-nitroaniline (p-NA) is in urgent need for security concerns and pollution supervision. In this work we report the use of molecularly imprinted polymeric ionic liquid (MIPIL) microspheres to construct recognizable surfaces for detection of p-NA through fluorescence quenching. The p-NA imprinted microspheres are synthesized by precipitation polymerization upon co-polymerization of 3-(anthracen-9-ylmethyl)-1-vinyl-1H-imidazol-3-ium chloride (Fluorescent IL monomer) with ethyleneglycol dimethacrylate (EGDMA). The electron-rich group alkenyl imidazole in IL functional monomer can dramatically improve the emission of anthracene fluorophore and the π-π stacking, electronic, and hydrogen bond between p-NA and MIPIL can efficiently enhance the selective recognition force. The as-synthesized MIPIL microspheres present spherical shape, high fluorescence emission intensity and specific recognition, which showed rapid detection rate (1min), stable reusable property (at least 4 time recycles), wonderful selectivity over several structural analogs, wide linear range (10nM to 10M) with a correlation coefficient of 0.992, and excellent sensitivity (LOD, 9nM). As synthesis and surface functionalization of MIPIL microspheres are well established, the methods reported in this work are facile, rapid and efficient for monitoring p-NA in environmental wastewater.

A simple approach for the sonochemical synthesis of Fe3O4-guargum nanocomposite and its catalytic reduction of p-nitroaniline.

In this present study, a facile and green method to synthesize highly stable Fe3O4-guar gum nanocomposite using ultrasound was reported. Thermal gravimetric analysis, fourier transform infrared spectroscopy, X-ray diffractometry, field emission scanning electron microscopy, energy dispersive spectroscopy, high resolution transmission electron microscopy and X-ray photoelectron spectroscopy were used to characterize the crystal structure, size and morphology, elemental composition, metal-metal and metal-oxygen bonds of the synthesized nanocomposites. Fe3O4-guar gum nanocomposite with a size of ∼48nm was obtained as from TEM. The physicochemical characterization supports the feasibility of guar gum as an efficient stabilizing agent for the formation of nanocomposite; guar gum acts as a capping agent with a zeta potential value of -34.8 which was found to be beneficial for achieving lower particle size. Guar gum serves as a matrix for both reduction and stabilization of nanocomposite. The HR-TEM and XPS shows that Fe3O4 nanoparticles are encapsulated by the guar gum polymeric networks or Fe3O4-guar gum core-shell structure. The guar gum encapsulated magnetite nanocomposite has performed better in terms of catalytic activity for the liquid phase reduction of p-nitroaniline. The simple catalytic reduction of p-nitroaniline showed an efficiency of 47% and further exceptional improvement of up to 98% reduction within 60min with the addition of sodium borohydride was achieved. The sonochemical synthesis of Fe3O4-guar gum nanocomposite does not require stringent experimental conditions or any toxic agents, and thus, a straightforward, rapid, efficient and green method for the fabrication of highly active catalysts for treating environmental pollutants.

Impact of a static magnetic field on biodegradation of wastewater compounds and bacteria recombination.

The current study presents results concerning the effect of a static magnetic field (SMF) on synthetic wastewater biodegradation by activated sludge and on dehydrogenase activity of microorganisms of activated sludge. The highest process efficiency was obtained for a SMF of 0.0075 T among the tested magnetic flux density values of 0.005-0.14 T. Decrease in COD was 25% higher for the bioreactor exposed to SMF compared with control experiments. The positive effect of SMF 0.0075-0.0080 T was confirmed in experiments on the dehydrogenase activity of activated sludge. It was also shown that a SMF of 0.007 T increased p-nitroaniline removal from wastewater and influenced the recombination frequency in a streptomycin-resistant bacteria strain of Eschercihia coli.

Development of highly-stable binder-free chemical sensor electrodes for p-nitroaniline detection.

Herein, pre-seeded fluorine doped tin oxide (FTO) glass substrates were used as an electrode for zinc oxide nanorods (ZnO NRs) growth by a low-temperature solution route in order to fabricate binder-free high-sensitive chemical sensor. The vertically-grown ZnO NRs exhibited a more favorable active morphology and improved sensing properties for p-nitroaniline (pNA) detection. On investigation with different concentrations of pNA, the ZnO NRs/FTO electrode showed an excellent sensitivity (10.18µAµM-1cm-2) and low detection limit (0.5µM) with good selectivity, outstanding long-term stability, and high reproducibility. Collectively, the present work emphasizes the potency of ZnO NRs/FTO electrodes for fabrication of an efficient and reliable chemical sensing device with improved performances.

Evaluation of concordance between labelling and content of 52 hair dye products: overview of the market of oxidative hair dye.

Hair dyes contain strong allergens and are widely available. Correct labelling is a necessity in order to provide information about the contents. To compare the labelling and content of hair dyes. In total, 52 hair dyes, from 11 different countries, were bought over the counter. High-pressure liquid chromatography was used for the analysis of p-phenylenediamine (PPD), toluene-2,5-diamine (2,5-TDA), and three oxidation products of PPD. There was good agreement between labelling and content, although seven of the 52 products (13.5%) studied were incorrectly labelled. There were differences in the geographical use of PPD and 2,5-TDA; 2,5-TDA was more common in European products, while PPD was more common in products purchased outside Europe and was present in higher concentrations. All dyes purchased in Europe contained PPD and 2,5-TDA at levels within the limits defined by European legislation, however, levels were higher in some products purchased outside Europe. Only a small group of hair dyes sold in Europe were mislabelled. Further improvement in labelling, by providing the concentration of chemicals, may facilitate products to be purchased both locally and within the global market, when travelling or on the internet.

Continuous treatment of the insensitive munitions compound N-methyl-p-nitro aniline (MNA) in an upflow anaerobic sludge blanket (UASB) bioreactor.

N-methyl-p-nitroaniline (MNA) is an ingredient of insensitive munitions (IM) compounds that serves as a plasticizer and helps reduce unwanted detonations. As its use becomes widespread, MNA waste streams will be generated, necessitating viable treatment options. We studied MNA biodegradation and its inhibition potential to a representative anaerobic microbial population in wastewater treatment, methanogens. Anaerobic biodegradation and toxicity assays were performed and an up-flow anaerobic sludge blanket reactor (UASB) was operated to test continuous degradation of MNA. MNA was transformed almost stoichiometrically to N-methyl-p-phenylenediamine (MPD). MPD was not mineralized; however, it was readily autoxidized and polymerized extensively upon aeration at pH = 9. In the UASB reactor, MNA was fully degraded up to a loading rate of 297.5 µM MNA d(-1). Regarding toxicity, MNA was very inhibitory to acetoclastic methanogens (IC50 = 103 µM) whereas MPD was much less toxic, causing only 13.9% inhibition at the highest concentration tested (1025 µM). The results taken as a whole indicate that anaerobic sludge can transform MNA to MPD continuously, and that the transformation decreases the cytotoxicity of the parent pollutant. MPD can be removed through extensive polymerization. These insights could help define efficient treatment options for waste streams polluted with MNA.

The synthesis process optimization of 1(- 4-aminophenyl)-5, 6-dihydro-3- (4-morpholinyl)-2(1H)-pyridinone, an important intermediate for the apixaban synthesis / 国际药学研究杂志

Objective: To optimize the synthesis process of 1-(4-aminophenyl)-5, 6-dihydro-3-(4-orpholinyl)-2(1H)-pyridinone.Methods: Using p-nitroaniline as the raw material, the target compound was obtained by amidation, cyclization, chlorination, nitration and reduction reactions. The sodium hydride catalyst for cyclization was taken out in the reaction, the reaction acid binding agent was improved, the reaction temperature of intermediate was reduced, the optimal ratio and reaction ratio condition were investigated, and the post-processing conditions were optimized for each reaction. Results: The target compound was confirmed by 1H NMR and 13C NMR data, and the total yield was 65.4%. Conclusion: The optimized process is simple to operate, mild and controllable, and the solvent is easy to recycle, low-polluting and more conducive to industrial production.