Thermal transformation of solid organic compounds

The thermal decomposition of malonic acid was investigated with a derivatograph. Values of activation energy, frequency factor and reaction order were determined from thermal decomposition curves employing different calculation methods. Equations derived for the calculation of kinetic data of inorganic thermal reactions were also found to be suitable in the case of organic reactions. Convenient methods were developed for the calculation of the activation energy, using the DTG curve.     

Sampling volatile organic compounds using a modified solid phase microextraction device

Headspace solid phase microextraction (headspace SPME) has been demonstrated to be an excellent solvent-free sampling method. One of the major factors contributing to the success of headspace SPME is the concentrating effect of the fiber coating toward organic compounds. The affinity of the fiber coating toward very volatile analytes, such as chloromethane, may, however, not be large enough for detection at the parts per trillion concentration level. Static headspace analysis, on the other hand, is very effective for these very volatile compounds. As analyte volatility decreases, the sensitivity of static headspace analysis drops. The complementary nature of these two sampling methods can be exploited by combining the SPME device with a gastight syringe. The sensitivity of the new sampling device is better than that of SPME for very volatile compounds or that of static headspace analysis for less volatile compounds. This new method can sample a wide range of compounds from chloromethane (b.p. −24°C) to bromoform (b.p. 149°C) with estimated limits of detection at the low parts per trillion level.     

Environmental analysis of organic compounds in water using solid phase micro extraction

Solid Phase Micro Extraction (SPME) involves exposing a fused silica fiber coated with stationary phase to a contaminated water sample. The organic analytes become partitioned between the stationary phase and the water and when equilibrium is reached the fiber is removed from the solution and the analytes are thermally desorbed in the injector of a gas chromatograph. The fiber is contained in a syringe to facilitate handling. Factors which affect linear range, limit of detection, and total analysis time are discussed with regard to the development of a method for analysis of volatile compounds in environmental water samples. The sensitivity of the method was determined by the thickness of the film of stationary phase; the equilibration time, however, increased with the film thickness, although it can be minimized by use of a cross-shaped stirrer bar. Increasing the thickness of stationary phase in the analytical column enables the cryofocusing temperature to be increased from ?40 to ?15°C. With an ion trap mass spectrometer, detection limits required by the US Environmental Protection Agency are met for all compounds except chloromethane and chloroethane. The method has been applied to environmental water samples.     

Extraction of europium from nitrate solutions in the presence of polyfunctional organic compounds

The extraction of europium with benzene solutions of tributyl phosphate (TBP), benzoic acid (BA), and acetylacetone (AA) from nitrate solutions has been studied in the presence of the following polyfunctional organic compounds: acrylamide (AAm), phenanthroline (Phen), Diacetam-5, and Tinuvin-622. Europium distribution data in combination with luminescence spectroscopy of extracts are used to discuss europium complexing with the specified ligands. A feasibility of manufacturing Eu₂O₃ and EuPO₄ films on quartz through the pyrolysis of saturated extracts is demonstrated.     

CVD of metal organic and other rare-earth compounds

Three major applications have been found for rare-earth compounds in Metal Organic Chemical Vapour Depostion (MOCVD) or Chemical Vapour Deposition (CVD). Yttrium 2,2,6,6-tetramethyl-3,5-heptanedionates and 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionates have been used in conjunction with barium and copper(II) β-diketonates to deposit YBa₂Cu₃O_7−δ as superconducting thin films. Rare-earth fluorides and chlorides have been used for CFD doping of rare earths into MOCVD-deposited ZnS, whilst yttrium chloride has been used, with barium iodide and copper(I) chloride, to produce YBa₂Cu₃O_7−δ superconducting material by CVD. Lanthanoid (Ln) tris(cyclopentadienyl) compounds, Ln(C₅H₅)₃ or Ln(C₅H₄Me)₃, have been used for doping of rare earths into 13–15 (III–V) semiconductors. Their volatility, structure/volatility relationships, and preparations are discussed. Possible alternative reagents and problems to be faced in doping 12–16 (II–VI) semiconductors are also considered.     

Rapid determination of volatile organic compounds in environmentally hazardous wastewaters using solid phase microextraction

Solid phase micro-extraction (SPME) was applied to the determination of volatile organic compounds (VOC) in wastewater discharges. Environmentally significant samples, typical of those subject to regulatory control, were examined and included discharges from pharmaceutical, petrochemical and municipal sewerage treatment plants. Analysis was performed using gas chromatography – mass spectrometry (GC-MS) following sampling using headspace or immersion SPME. Fused silica fibres, coated with either poly(dimethylsiloxane) or poly(acrylate), were examined to determine VOC which included chloroform, saturated carboxylic acids, alkylbenzenes, phenol, benzonitrile and benzofuran. Detection limits varied from 10 to 170 ng/ml and satisfactory relative standard deviations (%RSD < 10) were obtained. For most samples, headspace sampling was preferred to immersion. SPME was found to be a useful technique for the rapid screening of wastewaters for VOC.     

顶空固相微萃取-气相色谱-质谱联用分析纺织品中挥发性有机物

建立了顶空固相微萃取（HSSPME）-气相色谱（GC）-质谱（MS）联用测定纺织品中甲苯、4-乙烯基环己烯、苯乙烯、萘和1-苯基环己烯5种挥发性有机物（VOCs）的分析方法。选择聚二甲基硅氧烷（PDMS）作为萃取涂层,优化了SPME的萃取条件,包括平衡时间、萃取时间、萃取温度、顶空体积、离子强度、搅拌速度、解吸温度和时间以及GC—MS仪器条件。对于甲苯、4-乙烯基环己烯、苯乙烯、萘和1-苯基环己烯方法线性范围分别为0．087～870、3．32～3320、2．28～2280、0．015～150和0．050～50．0ng／g;检出限分别为0．005、0．042、0．670、0．008和0．011ng／g。实际样品加标回收率在80．1％～122％之间,RSD在0．8％～8．6％之间。方法符合纺织品中痕量VOCs的快速分析要求。     

Amino sulfonic acids,peptidosulfonamides and other related compounds

A review with 636 references. The literature on saturated amino sulfonic acids with primary/secondary amino group and their derivatives from XIX century to 2016 is surveyed, focusing mainly on results published in the last two decades. Synthesis of saturated amino sulfonic acids and their derivatives, their occurrence among natural products, as well as their use for design of peptidomimetics, conjugates with various molecules of practical significance, applications as building blocks for drug discovery and for other reasons are discussed.     

Terbium extraction in the presence of polyfunctional organic compounds and the composition of the extract pyrolysis products

Terbium extraction with benzene solutions of acetylacetone, bipyridine, and diphenylguanidine and their mixtures from aqueous chloride solutions, in particular, in the presence of tris(hydroxymethyl)aminomethane was studied. On the basis of terbium distribution in extraction systems in combination with IR and luminescence spectroscopy data for the extracts, the complexation of terbium with these ligands was discussed. The composition of the products of the pyrolysis of extracts was studied. It was shown that pyrolysis of saturated extracts can give nano-sized bulk samples and films on a quartz substrate for both terbium oxide and terbium and manganese mixed oxides.     

Extraction of phenolic compounds and organic acids by liquid membranes

Liquid membrane emulsions were used to extract phenolic compounds and organic acids from their aqueous solutions. The emulsions contained caustic as the reactive agent. When the phenolic compounds and organic acids permeated through the liquid membranes into the emulsion droplets, they reacted with caustic and became ionized. The ionized species could not permeate through the liquid membranes and therefore were held in the emulsion droplets.

The conclusions of this recent investigation are:

(1) More than 99% of phenol and cresols can be extracted in less than 1 minute.

(2) Acetic and propionic acids can also be extracted but at much slower rates. However, if the amount of caustic is not sufficient to react with all the permeating compounds, the acids will be extracted preferentially to the phenols.

(3) The acids can only be extracted at low pH (acidic) whereas the phenolic compounds can be extracted at pH of 7.

(4) The extraction rates for phenol and acetic acid are the same in individual-compound and binary-mixture permeations.

(5) The extraction can be described by a mass transfer model.     

Capillary electrophoresis method for the analysis of inorganic anions, organic acids, amino acids, nucleotides, carbohydrates and other anionic compounds.

A previously developed capillary zone electrophoresis (CZE) method with indirect UV detection for the simultaneous determination of inorganic and organic anions, amino acids and carbohydrates using 20 mM 2,6-pyridinedicarboxylic acid (PDC) as the background electrolyte was extended to allow determination of 206 anions including those above--mentioned and physiological amino acids, nucleotides, aromatic acids, haloacetic acids, alcohols, phosphorylated saccharides, oxyhalides, metal oxoacids, metal-ethylenediaminetetraacetic acid (EDTA) complexes, forensic anions, Good's buffers and herbicides. Every compound could be analyzed and their electrophoretic mobility determined simply by selecting detection wavelength. This method is simple and universal for anion analysis, and could be readily applied to the simultaneous determination of anionic compounds. In this work, it was used to identify and quantify important anions in sea urchin and sake.     

Microheterometric titrations of large organic nitrogen-containing compounds and of heteropoly acids

Micro amounts of nitron, quinine, strychnine, papaverine, yohimbine, nicotine, atropine, morphine or phenanthroline were titrated heterometrically with silicotungstic, phosphotungstic or phosphomolybdic acids at pH 1 or 7. The heterometric curves and the compounds obtained were studied. The reverse titrations were also studied. Microheterometric determinations of large nitrogen-containing compounds and heteropoly acids are suggested.     

Interactions of uracil and its derivatives with polyfunctional acids

Russian Chemical Bulletin - The previously obtained experimental and quantum chemical data on the composition, structure, stability, and thermodynamic properties of complexes of uracil and a series...     

The determination of volatile organic compounds in soils using solid phase microextraction with gas chromatography-mass spectrometry

Solid phase microextraction (SPME) was applied in the development of a protocol for the analysis of a number of target organic compounds in landfill site samples. The selected analytes, including aromatic hydrocarbons, chlorinated hydrocarbous, and unsaturated compounds, were absorbed directly from a headspace sample above a soil layer onto a fused silica fiber. Following exposure, the fiber was thermally desorbed in the injection port of the gas chromatograph and eluted compounds were detected using a mass selective detector. The stability and sensitivity of the extraction technique were examined at five temperatures (22–60°C) using a 100μm polydimethylsiloxane fiber. Calibrations, using soil samples spiked with selected solvents (0.5–30 μg/g), were linear; trichloroethene (r² = 0.992) and benzene (r² = 0.998). SPME was applied to the examination of a municipal landfill where 8 sites were sampled, at three depths, resulting in the detection of xylene (maximum 2.8 μg/g) and a number of other non-target organic contaminants.     

Synthesis of regular polypeptides including polyfunctional amino acids

Polypeptides of regular structure with the sequences His-Glu, Ser-Glu, Try-Glu, His-Tyr, and Glu-His have been synthesized by the 2,4,5-trichlorophenyl ester method. Polymerization was carried out in dimethyl sulfoxide and dimethylformamide. The polymers were purified by dialysis against water. In the process of synthesizing the monomers, theα-amino groups of the acids were protected by ortho-nitrophenylsulfenyl (o-NPS-), benzyloxycarbonyl (Z-), and tert-butoxycarbonyl (t-BOC-) groups. The imidazole group of histidine was Z-protected, and the γ-hydroxy group of glutamic acid and the phenolic OH group of tyrosine were benzyl-protected (Bzl-).