A method for the determination of histamine in wine by HPLC with precolumn derivatization with phenylisothiocyanate

Summary A method for determining histamine in wine by precolumn derivatization with PITC (phenylisothiocyanate) with reversed-phase HPLC and UV detection is reported. Histamine can be determined together with the 24 amino acids within 40 min, or separately in a shorter time (less than 4 min) if a prior solid phase extraction clean-up is used.     

Synthesis and crystal structure of 4-acetoxy-5,6-dihydro-5,5-dinitro-2H-1,3-oxazineN-oxide

A novel heterocyclic compound, 4-acetoxy-5,6-dihydro-5,5-dinitro-2H-1,3-oxazineN-oxide, has been synthesized by the reaction of the dipotassium salt of 1,1,5,5-tetranitro-3-oxapentane with aqueous acetic acid. The synthesized compound has been studied by X-ray diffraction analysis.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2207–2210, December, 1994.We would like to thank G. V. Lagodzinskaya (Institute of Chemical Physics in Chernogolovka, Russian Academy of Sciences) for recording and interpreting¹H NMR spectra, A. M. Korolev (Institute of Chemical Physics in Chernogolovka, Russian Academy of Sciences) for helpful discussion, and V. I. Fetisov (Institute of Physiologically Active Compounds, Russian Academy of Sciences) for performing quantum-chemical calculations by the AM1 SCF MO LCAO method.     

Structure,tautomerism, and transformations of β-(3-nitro-2-pyridyl)- and β-(3-nitro-4-pyridyl)pyruvic acid esters

It was shown by means of IR, UV, and PMR spectra that -(3-nitro-2-pyridyl)pyruvic acid esters are practically completely enolized in the crystal state and in solution; ethyl -(3-nitro-4-pyridyl)pyruvate has an enol structure in the crystalline state and in pyridine solution but exists as a mixture of keto and enol forms in low-polarity solvents.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 389–393, March, 1974.     

A new synthesis of ampicillin and related investigations

Quaternization of (S)-α-bromophenylacetic acid amide (8) with hexamethylentetramine (hexamine) preceded with ca. 80% inversion of configuration. Accordingly, starting from the trimethylsilylester of N-(S)-(α-bromo-α-phenylacetyl)-6-aminopenicillanic acid (4) quaternization with hexamine and subsequent hydrolysis afforded N-(R)-α-phenylglycyl-6-aminopenicillanic acid (1, ampicillin). Some other model reactions have been investigated.     

Nonequilibrium solid phase formation studied by lattice dynamics calculation and ion beam mixing in an immiscible Co-Ag system

For the equilibrium immiscible Co-Ag system, a proven realistic ab initio derived n-body potential is applied to study the nonequilibrium solid phase formation at three chemical stoichiometries of Co/Ag = 1:3, 1:1, and 3:1. To predict the structural stability, the elastic constants and the phonon spectra are calculated at the chosen stoichiometries with a total of eight hypothetical crystalline structures. The calculated results suggest that four compounds, that is, D0(3) CoAg3, B1 CoAg, B2 CoAg, and D0(3) Co3Ag, are unstable, as they all feature negative elastic constants as well as imaginary phonons, and that another four compounds of both fcc-type L1(2) and hcp-type D0(19) structures at chemical stoichiometries of Co/Ag = 1:3 and 3:1, respectively, may elastically be favored and therefore obtainable under some specific conditions. It is also found that all the calculated elastic constants and phonon spectra are coincident within the framework of the elastic theory. Moreover, the calculated elastic constants are in good agreement with those acquired directly from ab initio calculations, lending support to the validity of the ab initio derived n-body Co-Ag potential as well as its resultant elastic constants and the phonon spectra. Interestingly, some of the predicted nonequilibrium solid phases, that is, two hcp-type compounds at chemical stoichiometries of Co/Ag = 1:3 and 3:1, respectively, are indeed obtained in ion beam mixing experiments and their lattice constants determined by diffraction analysis are in good agreement with those from calculations.     

Multistage Electrochemical Reactions with the Transfer of Intermediates between Near-Electrode Layer and Bulk Solution: Analysis of a Kinetic Model and Computer-Aided Modeling

Kinetic equations for a multistage electrode process complicated by the transfer of intermediates between the near-electrode layer and bulk solution are derived and analyzed. Computer-aided modeling of the kinetics of processes of this kind is performed. Conditions under which the share of diffused intermediates is no longer vanishingly small are determined. Effect of various factors on the individual stages is established. Techniques of processing experimental data for determining kinetic parameters of separate stages are suggested.     

Thermal decomposition and indirect structural determination of rare earth element picrates with the dtso ligand

The complexes [Ln(pic)₃(DTSO)₃] (Ln=La, Lu and Y; pic=picrate; DTSO=1,3-dithiane-1-oxide) were synthesized and characterized. Indirect structural determination by far infrared spectroscopy is presented. Results from thermal decomposition of these complexes by TG/DTG and DSC techniques are reported. This revised version was published online in August 2006 with corrections to the Cover Date.     

Properties of Monocarboxy Cellulose Containing Sorbed Fe(III), Al(III), and Cr(III) Cations

Sorption of Fe(III), Al(III), and Cr(III) on monocarboxy cellulose at various pH, concentrations of metal chloride or sulfate in solution, and time was studied. The effect of type and amount of the cation sorbed on the physicomechanical properties, swelling, and stability in phosphate buffer of monocarboxy cellulose fibers was considered.     

Interconnection between the Structures and Sorption Characteristics of Mesophase Materials of MCM-41 Type Containing Alkylpyridines

Under the conditions studied for the synthesis of mesophase materials with alkylpyridinium halides an increase in the density of packing of these molecules in the encapsulated micelles was observed with an increase in the length of the alkyl radicals. The difference in the density of packing of these surface active reagents (SAR) depended to a considerable extent on the perfection of the hexagonal structure and the characteristic absorption properties of the mesophase materials of MCM-41 type.