Automized procedures for the determination of ozone and ammonia contents in air by using the chromatomembrane method for gas-liquid extraction

Chromatomembrane cells (CMC) operate as unique manifolds for extraction and preconcentration procedures in computer controlled flow-injection-analysis (FIA). By coupling to an ion chromatograph and to a conductometer, respectively, instrumentation is obtained that allows the pretreatment and the detection of ozone- and ammonia-containing samples after absorption of the gaseous constituents of air inside a chromatomembrane cell. The analysis of air even in the presence of liquid aerosols is discussed.     

Volumetric Properties of Tetraphenylporphyrin, Octaethylporphyrin, and Their Metallo Complexes in Organic Solvents

Densities, apparent molar volumes, and partial molar volumes were determined for (a) tetraphenylporphyrin, H₂TPP, and ZnTPP in several organic solvents and (b) H₂TPP, octaethylporphyrin, H₂OEP, and the metallo complexes MTPP and MOEP (where M = Zn, Cu, Ni, Pd, Cd, Ag) in benzene and chloroform solutions at 25°C. The effect of solute–solvent interactions on molecular packing was followed by examining changes in the ratios of van der Waals volumes to the partial molar volumes of solute and solvent. Using this method, the volumetric properties of H₂TPP were compared with those of the macromolecules 18-crown-6-ether, cryptand-222, and C60. For benzene solutions of MOEP metallo complexes, the linear dependence between the partial molar volumes and the half-wave oxidation potentials was determined. It was found that the partial molar volumes of MTPP in the chloroform solution correlate linearly with the distance between the metal atom and the nitrogen atom of the pyrrole moiety of the metallo complex.     

New chiral 1,4,2-oxazaphosphorinanes bearing a free hydroxy group

Russian Chemical Bulletin - New chiral 3-aryl-2-hydroxy-2-oxo-5-R-1,4,2-oxazaphosphorinanes were obtained by a three-step one-pot synthesis, which included the preparation of imines from...     

4-Methylamino antipyrine determination in human plasma by high-performance liquid chromatography tandem mass spectrometry

In the present study, a simple and rapid method for metamizole metabolite 4-methylamino antipyrine (MAA) determination in human plasma was developed, validated and successfully applied to a clinical trial. Chromatographic separation was achieved in HILIC mode on a YMC-Pack SIL column (100 × 2.0 mm; S-5 μm, 30 nm), with a mobile phase consisting of acetonitrile, water and formic acid. Protein precipitation of a small plasma volume using acetonitrile was selected for sample preparation. The multiple reaction monitoring transitions in the positive ionization mode were m/z 218.2 → 56.2 for MAA and m/z 221.2 → 56.2 for MAA-d3 (IS, internal standard). Concentration levels of MAA calibration standards were in the range of 0.100–20 μg/ml. Metamizole conversion into MAA in both water and organic media was investigated, and the level of the conversion in commercially available injection solutions was estimated.     

Stable and reproducible supramolecular motif in the crystal structure of sulfonamides of the benzothiazine series fused to an epoxybornane moiety

Russian Chemical Bulletin - The crystal structures of four sulfonamides of the benzothiazine series, fused to an epoxidized norbornane moiety and containing various substituents in the para...     

On Existence of Attractors in Dissipative Three-Dimensional Systems

International Applied Mechanics - The theorems on the birth of attractors from homoclinic loops are proved. Applications of the theorems are considered.     

Opening of the pyridine ring in the system 1,1,1-trifluoro-4-phenylbut-3-yn-2-one–water. Stereoselective synthesis of 5-{[(1Z)-4,4,4-trifluoro-3-oxo-1-phenylbut-1-en-1-yl]amino}penta-2,4-dienal

Russian Journal of Organic Chemistry -     

1-R-2-[(1E,3E)-4-Aminobuta-1,3-dien-1-yl]-1H-benzimidazoles. Synthesis and some transformations

7-Nitropyridobenzimidazolium salts are cleaved with secondary amines to form 2-[(E,E)-4-aminobuta-1,3-dienyl]-1H-benzimidazoles. The latter react with dimethyl acetylene-dicarboxylate to yield 4a-[(E,Z,E)-6-amino-4,5-dimethoxycarbonylhexa-1,3,5-trien-1-yl]-1,2,3,4-tetra(methoxycarbonyl)-4a,5-dihydropyrido[1,2-a]benzimidazoles.