Retention of analgin and anesthesin on sorbents with different polarities: The analysis of bellalgin tablets by high-performance liquid chromatography

The effects of acetonitrile and potassium dihydrogen phosphate concentrations in a mobile phase and the pH of the mobile phase on the retention of analgin (dipyrone) and anesthesin (benzocaine) on Symmetry C18 and Nova-Pak CN HP sorbents with grafted octadecylsilanol and nitrile groups, respectively, were studied. It was found that, under identical conditions, retention on the sorbent with grafted nitrile groups was weaker. A rapid and cost-effective procedure was developed for the determination of analgin and anesthesin in the analysis of Bellalgin tablets.     

Kinetic-chromatographic determination of 4-methylaminoantipyrine in Pentalgin N and Pentalgin FS tablets

4-Methylaminoantipyrine (4-MAAP) is the main product of analgin decomposition in aqueous-organic solutions used in the analysis of Pentalgin N and Pentalgin FS tablets. The determination of 4-MAAP in tablets is complicated by the fast decomposition of analgin in the course of sample dissolution. The use of nonaqueous solvents in subsequent HPLC analysis is unreasonable, because the shapes of analyte peaks are deteriorated and the decomposition of analgin is not prevented. A procedure for the kinetic-chromatographic determination of both 4-MAAP in tablets and its amount at the moment of sample dissolution is proposed.     

Layer arrangement in the structure of octakis-(trimethylsiloxy)octasilsesquioxane and dodecakis-(trimethylsiloxy)cyclohexasiloxane

Layers of [(CH₃)₃SiO]₈(SiO_1.5)₈ and [(CH₃)₃SiO]₁₂(SiO)₆ organosilicon compounds obtained by chemical vapor deposition were investigated by X-ray diffraction (DRON-RM4, R = 192 mm, CuK radiation) and Raman spectroscopy (Triplemate, SPEX). The layers were found to be ideally oriented polycrystalline films. The octakis-(trimethylsiloxy)octasilsesquioxane polycrystals are oriented in one crystallographic direction — [001], while the dodecakis-(trimethylsiloxy)cyclohexa-siloxane polycrystals are oriented in the and directions. Crystal structure analysis in these directions yielded the type of the planar lattice followed by the molecules and their orientation relative to the support.Original Russian Text Copyright © 2004 by S. A. Gromilov, T. V. Basova, D. Yu. Emelyanov, A. V. Kuzmin, and S. A. ProkhorovaTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 3, pp. 497–501, May–June 2004.     

Liquid chromatography of platinum metals and prospects of development

Summary A survey of the authors' work on liquid chromatography of platinum metals in the form of chelates with 1-(2-pyridylazo)-2-naphthol (PAN) is given. Extraction chromatography with PAN in isopentanol as a stationary phase was used to achieve a group concentration of these metals (Pd, Pt and Rh, concentration coefficient 100) from large volumes of aqueous solutions and a selective extraction of palladium from solutions containing other platinum, nonferrous and heavy metals on a 85–98° C thermostatted chromatographic column. The prospects for the use of liquid chromatography in the analysis of platinum metals are discussed.

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Flüssig-Chromatographie von Platinmetallen und zukünftige Entwicklungen

     

Synthesis and structures of germanium-containing tungsten carbyne complexes Ph3gec≡w(ch2but)3 and Ph3GeC≡W(CH2SiMe3)3

New germanium-containing tungsten carbyne complexes Ph₃GeC≡W(CH₂R)₃ (R = Bu^t or SiMe₃) were synthesized by the reaction of the alkoxy derivative Ph₃GeC≡W(OBu^t)₃ with alkyllithium reagents RCH₂Li. The new compounds were isolated in individual form as crystals in 95 and 90% yields, respectively, and were characterized by elemental analysis, ¹H and ¹³C NMR spectroscopy, and X-ray diffraction. X-ray diffraction study showed that the coordination environment of the W and Ge atoms in the Ph₃GeC≡ W(CH₂Bu^t)₃ and Ph₃GeC≡W(CH₂SiMe₃)₃ complexes can be described as a distorted tetrahedron. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 213—216, February, 2006.     

Hexachlorocuprate(II) Anion: Vibration Spectra and Structure

For the complexes (CH₈N₄)₂[CuCl₆], (C₂H₉N₅)₂[CuCl₆] · 2H₂O, and (CH₈N₄O)₄[CuCl₆]Cl₄, where (CH₈N₄)²⁺, (C₂H₉N₅)²⁺, and (CH₈N₄O)²⁺ are the aminoguanidinium, biguanidium, and carbohydrazidium cations, respectively, IR and Raman spectra were taken and analyzed in the region of Cu—Cl vibrations. Polarization measurements of the Raman spectra of (CH₈N₄O)₄[CuCl₆]Cl₄ single crystals were performed with the purpose of assigning the vibrations to symmetry types. Vibration spectra were calculated for the hexachlorocuprate ion in the given series of compounds, and the spectra of the examined complexes were compared with spectra of the previously known compounds incorporating the hexachlorocuprate(II) ion.     

Direct and Fast Electrochemical Determination of Catechin in Tea Extracts using SWCNT‐Subphthalocyanine Hybrid Material

In this study, single walled carbon nanotubes (SWCNTs) were covalently functionalized by terminal ethynyl bearing subphthalocyanine (SubPc) to obtain a new hybrid material, viz. SWCNT‐SubPc (CS), via “click” reaction for the first time. The structural characterization and study of the electrochemical sensor properties of the CS hybrid material to catechin were carried out. A convenient and fast analytical method was offered for the determination of catechin. It was shown that the deposition of CS on the surface of a glassy carbon electrode (GCE) led to a 2.2 and 8‐fold increase in the differential pulse voltammetry (DPV) responses to catechin in Britton‐Robinson (BR) buffer solution (a pH of 3) in comparison with SWCNT‐modified and bare GCE, respectively. The dynamic range, detection and quantification limits of catechin were determined to be 0.1–1.5 μM, 13 nM and 43 nM, respectively. Selectivity of the suggested CS/GCE sensor was investigated on addition of a number of interfering metal ions, antioxidants and biomolecules. The applicability of the modified electrode for the detection of catechin in real tea samples such as green, rosehip fruit, Turkish and Indian black tea was demonstrated with the standard addition method. Along with the ease in fabrication and low prices, the proposed CS/GCE sensor was reproducible, selective, stable and sensitive to catechin in major types of tea samples.     

The Theoretical and Experimental Investigation of the Fluorinated Palladium β-Diketonate Derivatives: Structure and Physicochemical Properties

To search for new suitable Pd precursors for MOCVD/ALD processes, the extended series of fluorinated palladium complexes [Pd(CH₃CXCHCO(R))₂] with β-diketone [tfa−1,1,1-trifluoro-2,4-pentanedionato (1); pfpa−5,5,6,6,6-pentafluoro-2,4-hexanedionato (3); hfba−5,5,6,6,7,7,7-heptafluoro-2,4-heptanedionato (5)] and β-iminoketone [i-tfa−1,1,1-trifluoro-2-imino-4-pentanonato (2); i-pfpa−5,5,6,6,6-pentafluoro-2-imino-4-hexanonato (4); i-hfba-5,5,6,6,7,7,7-heptafluoro-2-imino-4-heptanonato (6)] ligands were synthesized with 70–80% yields and characterized by a set of experimental (SXRD, XRD, IR, NMR spectroscopy, TG) and theoretical (DFT, Hirshfeld surface analysis) methods. Solutions of Pd β-diketonates contained both cis and trans isomers, while only trans isomers were detected in the solutions of Pd β-iminoketonates. The molecules 2–6 and new polymorphs of complexes 3 and 5 were arranged preferentially in stacks, and the distance between molecules in the stack generally increased with elongation of the fluorine chain in ligands. The H…F contacts were the main ones involved in the formation of packages of molecules 1–2, and C…F, F…F, NH…F contacts appeared in the structures of complexes 4–6. The stability of complexes and their polymorphs in the crystal phases were estimated from DFT calculations. The TG data showed that the volatility differences between Pd β-iminoketonates and Pd β-diketonates were minimized with the elongation of the fluorine chain in the ligands.