摘要:

Sensitive, spectrophotometric and densitometric methdos are described for the determination of meloxicam I and tetracaine hydrochloride II in the presence of their degradation products.

ISSN:0038-7010    

DOI:10.1080/00387019808007401

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This paper highlights the use of Raman, FT-Raman and surface-enhanced Raman scattering (SERS) techniques for the study of humic substances. In contrast to other technologies which reveal information only about the average compositions and the kinds of functional groups present in humic substances, Raman and especially FT-Raman spectroscopies characterize the building blocks of humic substances and their changes in derivation and separation processes. Furthermore, surface-enhanced Raman scattering (SERS) techniques are able to readily detect humic substances and co-existing organic species at low concentrations typically found in natural environments and reveal definitive information about the specific groups in humic substances that bind on metal electrodes. Further applications of both Raman and SERS techniques can be extended to complicated systems as well as real environmental samples. Experiments have demonstrated: (1). the backbones of humic substances are structurally disordered carbon networks in most cases; (2). The backbones of humic substances from different sources and types are similar to each other; (3). Normal Raman spectroscopic study of humic substances should concentrate on the use of near-IR laser(s) resulting from strong fluorescence background and self-adsorption under the excitation with visible laser irradiation; (4). FT-Raman spectroscopy is the required analytical method to assess the effectivity of fractionation methods; (5). SERS spectra of humic substances on metal colloids and films are in most aces very similar to the corresponding Raman spectra of neutralized samples; (6). SERS techniques are very sensitive and highly selective, also both visible lasers and near-IR lasers can be used for SERS study; (7). SERS spectra on metal electrodes may provide additional information about the binding sites and adsorption mechanisms of humic substances on metal surfaces.

ISSN:0038-7010    

DOI:10.1080/00387019808007402

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The electron spin resonance (ESR) of radicals obtained by electrolytic reduction of 4-[2-(3,4-Dimethoxiphenyl)ethyl]-1-(5-nitrofurfurylidine)semicarbazide and 4-[2-(3,4-Dimethoxyphenyl)ethyl]-1-(5-nitrothienilydene)semicarbazide were measured in DMSO. The electrochemistry of these compounds was studied in DMSO, DMF and ACN using cyclic voltammetry.

ISSN:0038-7010    

DOI:10.1080/00387019808007403

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The spectroscopic properties of hydrotalcite-like compounds, containing Co(II) and Fe(III) in the layers, have been studied. In these materials, depending on the experimental conditions during synthesis, Co(II) becomes partially oxidized to Co(III). Although the environment of the cations is close to octahedral in all cases, Mossbauer data indicate a more symmetric environment for Fe(III) ions in samples not submitted to hydrothermal treatment. The FT-IR spectra show some distortion of the carbonate anions in the interlayer space.

ISSN:0038-7010    

DOI:10.1080/00387019808007404

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Novel iron(II) complex of 2,4,6-triphenylbenzenethiolate (tpbt) was synthesized by ligand exchange reaction of (Et4N)2[FeII(S-t-Bu)4] with tpbt-H. The complex shows absorption maxima at 277 nm (36500 M−1cm−1) and 367 nm (22800 M−1cm−1), and Fe2+/Fe3+redox potential at-0.78 V vs SCE in acetonitrile. While in tetrahydrofuran solution, the complex is found to be unstable and form a Fe(II) complex with low coordination number.

ISSN:0038-7010    

DOI:10.1080/00387019808007405

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Fourier transform surface enhanced Raman spectrometer is used to characterize Ω-mercaptoalkanols (HO(CH2)nSH, n=2, 6) chemisorption on silver surface from their aqueous solution of different pH values.

ISSN:0038-7010    

DOI:10.1080/00387019808007406

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A new synthesis and the crystal structure of C12H12N2S2have been described and redetermined. In order to optimize the geometry of the molecule, the semi empirical methods MNDO, AMI and PM3 were used. The conformation of the energy profile showed that the minimum energy conformation has the torsion angle [Cl-Sl-Sl′-Cl′] near 90°. The energy barrier at 0° attributed to the lone pair repulsion of sulphur atoms and interactions between NH…S and H(C6)…S non-bonded atoms.

ISSN:0038-7010    

DOI:10.1080/00387019808007407

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor