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... Sensitive detection of atmospheric formaldehyde and acetaldehyde can be achieved by use of silica-gel cartridges impregnated with 2-diphenylacetyl-1,3-indandione-1-hydrazone (DAIH) to form fluorescent DAI hydrazones. The hydrazones are extracted with acetonitrile and separated by reversed-phase HPLC with fluorimetric detection. The low detection limits achieved (0.25 ppb CH₂O or CH₃CHO for samplin ...
... Agricultural practices may cause contamination of soil and ground water with a combination of organic compounds (pesticides and fuel) and nitrogen fertilizers. In coupled microcosm studies that monitored the mineralization of naphthalene and the nitrification of ammonia, it was observed that the solvent (dichloromethane) used to apply naphthalene to the soil inhibited nitrification, although there ...
... Two hydrazine reagents, 4-N,N-dimethylamino-6-(4′-methoxy-1′-naphthyl)-1,3,5-triazine-2-hydrazine (DMNTH) and N-methyl-4-N′,N′-dimethylamino-6-(4′-methoxy-1′-naphthyl)-1,3,5-triazine-2-hydrazine (MDMNTH) have been synthesized and used for the determination of aldehydes in air samples. Test tubes with the reagents coated on silica gel were prepared and used for monitoring of carbonyls in air. After ...
acetonitrile; air; ammonia; detection limit; high performance liquid chromatography; mass spectrometry; microbial culture; monitoring; screening; secondary amines; tires
Abstract:
... High-performance liquid chromatography with mass spectrometric detection was used for the structure elucidation of eighteen primary and secondary amines and ammonia derivatised with naphthylisothiocyanate (NIT). A fragmentation scheme was established using reference compounds and the scheme was applied to real air samples from a tyre repair shop and from the air above a bacterial culture. The samp ...
acetonitrile; air; formaldehyde; high performance liquid chromatography; hydrazine; nitrogen dioxide; oxidants; ozone; phosphoric acid; samplers; silica gel
Abstract:
... A diffusive sampling device is described that is capable of reliable measurements of formaldehyde and total oxidants (Ox = ozone + nitrogen dioxide) at sub-ppbv concentration levels in ambient air. These species are collected on silica gel particles coated with 1-methyl-1-(2,4-dinitrophenyl)hydrazine (MDNPH) and phosphoric acid. The formaldehyde hydrazone (HCHO-MDNPh) and the N-methyl-2,4-dinitroa ...
acetonitrile; air; equations; heat; high performance liquid chromatography; permeability; silica; stainless steel; surface area; temperature profiles; viscosity
Abstract:
... The behavior of four similar liquid chromatography columns (2.1mm i.d. x 30, 50, 100, and 150mm, all packed with fine particles, average [formula removed]m, of bridged ethylsiloxane/silica hybrid-C₁₈, named BEH-C₁₈) was studied in wide ranges of temperature and pressure. The pressure and the temperature dependencies of the viscosity and the density of the eluent (pure acetonitrile) along the colum ...
... Selective and efficient aerobic oxidative iodination of ketones in aqueous media was achieved by using molecular iodine as the source of iodine atoms, air as the terminal oxidant, sodium nitrite (NaNO₂) as the catalyst and H₂SO₄ as the activator of the overall catalytic process. The efficiency of the reaction, resulting in α-iodo ketones, was significantly improved in an aqueous solution of the an ...
... Few studies were conducted on oxygenated volatile organic compounds (OVOC) because of problems encountered during the sampling/analyzing steps induced by water in sampled air. Consequently, there is a lack of knowledge of their spatial and temporal trends and their origins in ambient air. In this study, an analyzer consisted of a thermal desorber (TD) interfaced with a gas chromatograph (GC) and a ...
acetonitrile; air; chromatography; friction; heat; streams; temperature
Abstract:
... The apparent reduced HETP (height equivalent to a theoretical plate) of columns packed with very fine 1.7 μm BEH-C₁₈particles were measured under isocratic conditions, for different thermal conditions applied to the surface wall (column left in still-air at laboratory temperature, column placed in the oven of the Acquity UPLC chromatograph heated at different temperatures, or column immersed in a ...
acetonitrile; air; carbon dioxide; catalytic activity; copper; electrochemistry; electrodes; feedstocks; global warming; hydrogen; lithium; oxalates; oxygen; superoxide anion; value added
Abstract:
... Global warming concern has dramatically increased interest in using CO₂ as a feedstock for preparation of value-added compounds, thereby helping to reduce its atmospheric concentration. Here, we describe a dinuclear copper(I) complex that is oxidized in air by CO₂ rather than O₂; the product is a tetranuclear copper(II) complex containing two bridging CO₂-derived oxalate groups. Treatment of the c ...
... A two-step wet chemistry protocol has been developed for the surface derivatization of poly(ethylene terephthalate) (PET) track-etched membrane used as cell culturing support, that is, (a) activation by trifluorotriazine (1 M in acetonitrile (ACN), 30 °C, 3 h); (b) coupling to amine-terminated molecules, namely 3,5-bis(trifluoromethyl)benzylamine ((F)Tag), (L)-4,5-[³H]-lysine, and Gly-Arg-Gly-Asp- ...
... A new analytical method for the simultaneous determination of phthalic, isophthalic and 14 long-chain dicarboxylic acids in ambient aerosols by ultra-performance liquid chromatography/time-of-flight mass spectrometry with negative-ion electrospray ionization was developed and validated. A fast and quantitative pressurized fluid extraction procedure with water as solvent was optimized using samplin ...
X-ray diffraction; acetonitrile; air; benzaldehyde; bromides; catalysts; catalytic activity; cellulose; ethanol; hydrazine; mixing; oxidation; oxygen; palladium; scanning electron microscopes; scanning electron microscopy; thermal analysis; transmission electron microscopes; transmission electron microscopy
Abstract:
... Nano palladium(0) supported on cellulose was found to be highly efficient recyclable heterogeneous catalyst for the Suzuki coupling between aryl bromides and phenyl boronic acid in water and aerobic oxidation of benzyl alcohols using air as the source of molecular oxygen in acetonitrile. The Cell-Pd(0) was prepared by stirring commercially available cellulose with Pd(OAc)₂ in ethanol at 25°C follo ...
... Organosulfates of monoterpenes and isoprene, as well as their oxidation products have been identified in biogenic secondary organic aerosols (BSOA) from both laboratory and field studies. Organosulfates provide an interesting coupling between air pollution and formation of low-volatility BSOA. HPLC quadrupole time-of-flight mass spectrometry was used to study polar acidic monoterpene and isoprene ...
... Oxidative desulfurization of hydrogenation diesel (40mL) was studied using air as oxidant, tert-butyl hydroperoxide (TBHP) as radical initiator at ambient pressure and moderate temperature in the presence of isobutyl aldehyde. TBHP could accelerate the production of carbonyl radical and its peroxidation. When the molar fraction of TBHP was 5mmol, the conversion of DBT could reach 96.1% in the pres ...
acetonitrile; air; chemical structure; molecular weight; molybdenum; oils; oxidation; synthesis; temperature
Abstract:
... The novel molybdenum(IV) compound [MoO(NCMe)₅][B(C₆F₅)₄]₂ (1a) has been prepared by air oxidation of [Mo(CO)₃(NCMe)₃] in the presence of [H(OEt₂)₂][B(C₆F₅)₄] at room temperature. The [MoO(NCMe)₅]²⁺ cation shows a distorted octahedral configuration with two different acetonitrile-metal bond lengths due to a trans effect of the oxo-ligand. The trans-acetonitrile ligand is easily abstracted under oil ...
... During the ARCPAC (Aerosol, Radiation, and Cloud Processes affecting Arctic Climate) campaign in April 2008, several flights of the WP-3D research aircraft over the Arctic Ocean and Alaska sampled relatively rich bromine monoxide (BrO > 5 pptv) air masses in the free troposphere. In most cases air masses were identified as either stratospheric intrusions or as being recently in contact with sea-ic ...
... We demonstrate the application of corona discharge ion mobility spectrometry with orthogonal acceleration time of flight mass spectrometry (CD IMS-oaTOF) for volatile organic compounds (VOCs) monitoring. Two-dimensional (2D) IMS-oaTOF spectra of VOCs were recorded in nearly real time. The corona discharge atmospheric pressure chemical ionization (APCI) source was operated in positive mode in nitro ...
acetonitrile; air; aldehydes; alkenes; benzoquinones; chemical structure; oxidation
Abstract:
... A method for efficient and aldehyde-selective Wacker oxidation of aryl-substituted olefins using PdCl₂(MeCN)₂, 1,4-benzoquinone, and t-BuOH in air is described. Up to a 96% yield of aldehyde can be obtained, and up to 99% selectivity can be achieved with styrene-related substrates. ...
... A reinvestigation of the formal hydride transfer reaction of 1-benzyl-3-cyanoquinolinium ion (BQCN⁺) with N-methyl-9,10-dihydroacridine (MAH) in acetonitrile (AN) confirmed that the reaction takes place in more than one step and revealed a new mechanism that had not previously been considered. These facts are unequivocally established on the basis of conventional pseudo-first-order kinetics. It wa ...
acetonitrile; air; catalytic activity; chemical bonding; cyanides; dissociation; gas chromatography-mass spectrometry; gold; hydroxybenzaldehyde; irradiation; nanogold; nuclear magnetic resonance spectroscopy; photosynthesis; porous media; silica; transmission electron microscopy; trapping; ultraviolet radiation
Abstract:
... We show here the first radical route for the direct photosynthesis of AuCN oligomers with different sizes and shapes, as evidenced by TEM observations, from an Au nanoparticle/benzaldehyde/CH₃CN ternary system in air under UV-light irradiation. This photochemical route is green, mild, and universal, which makes itself distinguishable from the common cyanidation process. Several elementary reaction ...
... The reaction of a Cu(ii)–nitrosyl complex (1) with hydrogen peroxide at −20 °C in acetonitrile results in the formation of the corresponding Cu(i)–peroxynitrite intermediate. The reduction of the Cu(ii) center was monitored by UV-visible spectroscopic studies. Formation of the peroxynitrite intermediate has been confirmed by its characteristic phenol ring nitration reaction as well as isolation of ...
... The properties of fluid interfaces increase in importance as the physical scale decreases and, hence, characterization of surface tension becomes all the more critical. However, there is to date no method to characterize this parameter on microscale surfaces. We propose here a simple method based on the resonance of capillary waves, which are naturally excited by thermal fluctuations, under one-di ...
acetonitrile; air; black tea; detection limit; epigallocatechin gallate; gallic acid; green tea; high performance liquid chromatography; methanol; pH; tea bags
Abstract:
... A rapid and accurate High Performance Liquid Chromatography (HPLC) method for determination of gallic acid, caffein, and epigallocatechin gallate (EGCG) with an isocratic mobile phase elution was developed. HPLC parameters consisted of a C18 reversed-phase column (Eurosphere C18, 250 × 4.6 mm i.d., 5μm), mobile phase composed of 0.1% ortho phosporic acid : water : acetonitrile : methanol (14 : 7 : ...
... Surface degradation of profenofos (PF), a VX nerve gas surrogate, was investigated using in situ photo-oxidation that combines simple instrumentation and ambient gases (O₂ and H₂O) as a function of exposure conditions ([O₃], [OH], UV light λ = 185 and/or 254 nm, relative humidity) and PF film surface density (0.38–3.8 g m–²). PF film 0.38 g m–² fully degraded after 60 min of exposure to both 254 a ...
... We developed a CZE method for simultaneous determination of pyridine-triphenylborane (PTPB) anti-fouling agent and its degradation products such as diphenylborinic acid (DPB), phenylboronic acid (MPB), and phenol in artificial seawater (ASW) with no extraction procedure. The ASW samples, in which 20 % (v/v) acetonitrile was added, were injected directly into the capillary using vacuum injection. A ...
acetonitrile; air; aldehydes; ammonium chloride; chemical reactions; chemical structure; pyridines; solvents; synthesis; triethylamine
Abstract:
... A number of 2,4-disubstituted pyridines have been synthesized using α,β,γ,δ-unsaturated aldehydes and ammonium chloride in the presence of triethylamine in acetonitrile solvent at 80°C under air balloon. ...
... An analytical methodology using Accelerated Solvent Extraction (ASE) and a sylilation procedure coupled to Solid Phase Micro-Extraction (SPME) and GC/MS was developed for the determination of 31 pesticides of different chemical classes (urea, phenoxy acids, pyrethrenoïds, etc.) commonly used in non-agricultural areas in atmospheric samples. This methodology was developed to evaluate the outdoor at ...
Raja clavata; acetonitrile; air; biodegradation; derivatization; detection limit; dimethylamine; fish; headspace analysis; high performance liquid chromatography; liquids; methylamine; methylation; spoilage; total volatile basic nitrogen; trimethylamine
Abstract:
... An HPLC-UV method coupled with 9-fluorenylmethylchloroformate (FMOC) derivatization was developed for the determination of short chained amines in an environmental matrix. The basic reaction conditions among different target compounds (three methylated amines: mono- (MA), di- (DMA), and tri-methylamine (TMA)) with the reagent (FMOC) have been investigated. Comparative calibration of TMA as an indi ...
... A stability-indicating ultra-high-performance liquid chromatography (UHPLC) method with a diode array detector was developed and validated for the determination of cis/trans isomers of perindopril L-arginine in bulk substance and pharmaceutical dosage form. The separation was achieved on a Poroshell 120 Hilic (4.6 × 150 mm, 2.7 µm) column using a mobile phase composed of acetonitrile–0.1 % formic ...
acetonitrile; air; crystallization; ethanol; gold; hot water treatment; irradiation; nanogold; photocatalysis; photocatalysts; solvents; titanium dioxide; ultraviolet radiation
Abstract:
... Submicrometer-sized amorphous titania spheres incorporating Au nanoparticles (NPs) were prepared in a one-pot synthesis consisting of a sol–gel reaction of titanium(IV) isopropoxide in the presence of chloroauric acid and a successive reduction with sodium borohydride in a mixed solvent of ethanol/acetonitrile. The synthesis was allowed to prepare monodisperse titania spheres that homogeneously in ...
... Epoxidation of styrene is one of the key reactions in organic synthesis. In this paper, we investigated the effect of different metal ions in MIL-101 metal–organic framework on styrene epoxidation using various oxidants such as air, H₂O₂ and TBHP. For the aerobic epoxidation of styrene, Fe-MIL-101 and Cr-MIL-101 presented good styrene conversion (87.2 vs. 65.5%) and epoxide selectivity (54.4% vs. ...
... Tobacco smoke residues lingering in the indoor environment, also termed thirdhand smoke (THS), can be a source of long-term exposure to harmful pollutants. THS composition is affected by chemical transformations and by air–surface partitioning over time scales of minutes to months. This study identified and quantified airborne THS pollutants available for respiratory exposure, identified potential ...
... A long-term air-stable n-type organic semiconductor, 2,5-difluoro-1,4-phenylene-bis{2-[4-(trifluoromethyl)phenyl]acrylonitrile}, was synthesized by a high-yield simple procedure of Knoevenagel condensation with aldehyde and acetonitrile derivatives. A fabricated organic thin-film transistor (OTFT) using this compound exhibited good n-channel OTFT properties with a high electron mobility of 0.17 cm ...
acetonitrile; air; chemical bonding; chemical reactions; chemical structure; iodine; phosphorus
Abstract:
... We report an efficient metal-free azaphosphaannulation of a myriad of phosphonamides through intramolecular oxidative C–N bond formation using PhI(OAc)₂ and iodine in acetonitrile under air, thus leading to the formation of benzazaphosphol-3-one 1-oxides, which are novel phosphorus heterocyclic privileged structures. ...
... Fine aerosol particles in the urban areas of Shanghai and Los Angeles were collected on days that were characterized by their stagnant air and high organic aerosol concentrations. They were analyzed by nanospray-desorption electrospray ionization mass spectrometry with high mass resolution (m/Δm = 100,000). Solvent mixtures of acetonitrile and water and acetonitrile and toluene were used to extrac ...
... Nitrogen-doped turbostratic carbon nanoparticles (NPs) are prepared using fast single-step flame synthesis by directly burning acetonitrile in air atmosphere and investigated as an anode material for lithium-ion batteries. The as-prepared N-doped carbon NPs show excellent Li-ion stoarage properties with initial discharge capacity of 596 mA h g–¹, which is 17% more than that shown by the correspond ...
... (dpd)₂Cu₂Cl₆ has been prepared by the reaction of bis(1,1-diethyl-3-benzoyl-thioureato)-copper(II) with SOCl₂ in nitromethane. The brown air stable crystals were characterized by X-ray structure determination. Space group P2₁/n, Z = 4, 4222 observed unique reflexions, R = 0.053, Lattice dimensions (22 °C): a = 1336.4(2), b = 1677.2(9), c = 749.3(2) pm; β = 92.46(2)°. Similar reaction in acetonitri ...
... Air and moisture insensitive palladium complexes, [Pd(L)Cl₂] (1/2), in which L = 1-benzyl-4-phenylthiomethyl or 1-benzyl-4-phenylselenomethyl-1H-1,2,3-triazole (L1 or L2) catalyze Heck (HC) and Suzuki–Miyaura coupling (SMC) reactions between a series of aryl bromides including deactivated bromides and n-butyl acrylate and phenylboronic acid, respectively. The optimal catalytic loading was found to ...
Angela K. Baker; Sebastian Traud; Carl A.M. Brenninkmeijer; Peter Hoor; Marco Neumaier; David E. Oram; Armin Rauthe-Schöch; Detlev Sprung; Sebastian Schloegl; Franz Slemr; Peter F.J. van Velthoven; Heini Wernli; Andreas Zahn; Helmut Ziereis
acetonitrile; air; aircraft; atmospheric chemistry; biofuels; biomass; burning; carbon monoxide; case studies; convection; emissions; fossil fuels; pollutants; propane; summer; troposphere; Central Asia; Eastern European region; Germany; India; Middle East; North America; Philippines; West Asia; Western European region
Abstract:
... Between May 2005 and March 2008 the CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) observatory was deployed to make atmospheric observations on 42 flights between Frankfurt, Germany and Manila, the Philippines. This nearly 3 year flight series provides information about atmospheric composition in the upper troposphere over Europe and Asia ...
... A new polymorph of the copper(II) thiocyanate complex with 2-dimethylaminoethanol, [Cu₂(Me₂Ea)₂(NCS)₂]∞ (HMe₂Ea = 2-dimethylaminoethanol, HL) 1, was isolated in the attempted synthesis of a mixed-metal complex from zerovalent copper, cadmium oxide and ammonium thiocyanate in CH₃CN solution of HL in air. [Cu₂(Me₂Ea)₂(NCS)₂(DMSO)₂] ₂ is a product of recrystallization of 1 from DMSO. X-ray analysis c ...
... We reported a ligand- and additive-free Cu(OAc)2/TEMPO catalyst system that enables efficient and selective aerobic oxidation of a broad range of primary and secondary benzylic alcohols, primary and secondary 1-heteroaryl alcohols, cinnamyl alcohols, and aliphatic alcohols to the corresponding aldehydes and ketones. This ambient temperature oxidation protocol is of practical features like aqueous ...
... MTiX (M = Cr and V) samples, with 0, 5, 10 and 20 atomic percent, were synthesised by a sol–gel method and calcined at 400 °C in air. The XRD analysis results indicated that the materials presented a crystalline structure with the presence of TiO₂ anatase forms. BET analysis showed that the surface area varied with the variation of metal content. EDX analysis showed a heterogeneous distribution of ...
... The photo-induced decarbonylation of Cp*Cr(CO)₂NO in acetonitrile solution in the presence of excess sulfur leads to the cyclo-pentasulfido complex Cp*Cr(NO)(S₅) (1 a), while in the case of limited sulfur supply the binuclear bis(µ-disulfido) complex Cp*₂Cr₂(NO)₂(µ-S₂)₂ (4a) is formed preferentially. The corresponding reaction with elemental selenium produces Cp*₂Cr₂(NO)₂(µ-Se₂)₂ (4b), irrespectiv ...
... [Fe(2,2'-bpy)₃][Fe₂OCl₆] is obtained in form of red, air stable crystals by oxidation of Fe(bpy)Cl₂ with O₂ in acetonitrile. It crystallizes in the monoclinic space group P2₁/c with Z = 4. The crystal structure contains Fe(bpy)₃²⁺ and Fe₂OCl₆²⁻ ions. The anion exhibits a bent oxobridge with Fe-O-Fe = 148,1° and Fe-O distances of equal length (176,5 pm). In the IR spectrum νₐₛ Fe-O-Fe is observed a ...
... The title compound, [(Ph₃PO)₄Li]⁺ AuI₂ ⁻, crystallized from a reaction mixture obtained from Ph₃PAuC≡CPh, LiMe and MeI (molar ratio 1 : 1 : 2) in diethylether upon subsequent oxidation in air. The triclinic crystals, space group P1̅, are isomorphous with those of the corresponding di(bromo)cuprate(I). The gold atoms of the two independent [AuI2]− anions reside on centers of inversion and have no c ...
... Light blue [Cu(CN)en₂]I was prepared by reaction of copper iodide with ethylenediamine (en) and potassium cyanide in acetonitrile in air. It crystallizes in the space group C2 (No. 5) with a = 11.082(6), b = 7.155(2), c = 9.017(3) Å , β = 127.00(3)°, and Z = 2. The structure was refined from 1069 unique reflections and 90 parameters. The refinement converged to R1=0.018 and wR2=0.041 (all reflecti ...
acetonitrile; air; chlorpyrifos; correlation; detection limit; environmental health; foams; gas chromatography-mass spectrometry; liquid chromatography; monitoring; oxygen; polyurethanes; spray drift; stable isotopes; storage quality; tandem mass spectrometry
Abstract:
... A rapid liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed for determination of levels of the organophosphorus (OP) pesticides chlorpyrifos (CPF), azinphos methyl (AZM), and their oxygen analogs chlorpyrifos-oxon (CPF-O) and azinphos methyl-oxon (AZM-O) on common active air sampling matrices. XAD-2 resin and polyurethane foam (PUF) matrices were extracted with acet ...
... An extraction procedure based on the Quick Easy Cheap Effective Rugged and Safe (QuEChERS) approach has been developed and used for analysis of particle-bound nitrated and oxygenated PAH derivatives (NPAH and OPAH, respectively). Several analytical conditions, for example GC injection temperature and MS detection settings, were optimized. This analytical procedure enabled simultaneous GC–NICIMS qu ...
acetonitrile; air; ammonia; dielectrophoresis; electric current; electric field; electrodes; electrophoresis; nanomaterials; prototypes; temperature
Abstract:
... Interconnected network of nanostructured polyaniline (PANI) is giving strong potential for enhancing device performances than bulk PANI counterparts. For nanostructured device processing, the main challenge is to get prototypes on large area by requiring precision, low cost and high rate assembly. Among processes meeting these requests, the alternate current electric fields are often used for nano ...