114 research outputs found
Determination of phenolic compounds in medicinal preparations by galvanostatic coulometry
In this work, the possibility of using reactions of electrogenerated titrants with phenolic compounds was studied and a method for their coulometric determination in medicaments by galvanostatic coulometry was developed. The research objects were: rutin, salicylic acid and drugs containing phenolic compounds such as «Ascorutin», «Salicylic Paste» and «Salicylic Ointment» of Russian manufacture. Electrogenerated halogens (Cl2, Br2 and I2) and hexacyanoferrate(III)-ions were used as titrants. It was found that for the quantitative determination of phenolic acids, the optimal reagent is electrogenerated bromine, for rutin - electrogenerated bromine and iodine, and for ascorbic acid - any of the studied electrogenerated titrants (Cl2, Br2, I2 and [Fe(CN)6]3-). The correct definition was checked by the «entered-found» method, the error does not exceed 2%. As experimental studies have shown, our method of coulometric titration with electrogenated bromine and iodine is characterized by good reproducibility of results, expression, accuracy and can be used to determine phenolic compounds in drugs, for example, «Ascorutin» tablets. It should be noted that by our procedure it is possible to determine the spectrum of phenol-containing compounds (rutin, ascorbic and salicylic acids) in drugs without their preliminary separation. Therefore, the coulometric method using electrogenerated titrants can be recommended for the determination of salicylic, ascorbic acids and rutin in dosage forms. The proposed method is accurate and eliminates the experiment error in comparison with the Pharmacopoeic method
APPLICATION OF GALVANOSTATIC COULOMETRY FOR DETERMINATION OF PHENOLIC COMPOUNDS IN MEDICINAL PREPARATIONS
The objects of the study were: rutin - as a representative of the class of flavonoids and polyphenols; salicylic acid as a representative of phenolic acids and drugs containing phenolic compounds such as “Ascorutin”, “Salicylic Paste” and “Salicylic Ointment”. The titrants used were electrogenated halogens (Cl2, Br2 and I2) and hexacyanoferrate (III) ions. Generation was carried out at a constant current strength of I = 10 mA, and the equivalence point was fixed biamperometrically with two polarized electrodes on the coulometric analyzer “Expert-006”. The selected halogens are not only capable of oxidizing phenolic compounds, but also enter into electrophilic substitution reactions of the benzene ring, while the hexacyanoferrate(III)-ions [Fe (CN)6]3- are mild oxidizing agents
BioProject and BioSample databases at NCBI: facilitating capture and organization of metadata
As the volume and complexity of data sets archived at NCBI grow rapidly, so does the need to gather and organize the associated metadata. Although metadata has been collected for some archival databases, previously, there was no centralized approach at NCBI for collecting this information and using it across databases. The BioProject database was recently established to facilitate organization and classification of project data submitted to NCBI, EBI and DDBJ databases. It captures descriptive information about research projects that result in high volume submissions to archival databases, ties together related data across multiple archives and serves as a central portal by which to inform users of data availability. Concomitantly, the BioSample database is being developed to capture descriptive information about the biological samples investigated in projects. BioProject and BioSample records link to corresponding data stored in archival repositories. Submissions are supported by a web-based Submission Portal that guides users through a series of forms for input of rich metadata describing their projects and samples. Together, these databases offer improved ways for users to query, locate, integrate and interpret the masses of data held in NCBI's archival repositories. The BioProject and BioSample databases are available at http://www.ncbi.nlm.nih.gov/bioproject and http://www.ncbi.nlm.nih.gov/biosample, respectively
Measurement of the Analyzing Power in \\with a Fast Forward --Diproton
A measurement of the analyzing power of the
reaction was carried out at beam energies of 0.5 and 0.8 GeV by detection of a
fast forward proton pair of small excitation energy MeV. The
kinematically complete experiment made use of the ANKE spectrometer at the
internal beam of COSY and a deuterium cluster--jet target. For the first time
the --wave dominance in the fast diproton is experimentally demonstrated in
this reaction. While at GeV the measured analyzing power
vanishes, it reaches almost unity at GeV for neutrons scattered at
. The results are compared with a model taking into
account one--nucleon exchange, single scattering and (1232) excitation
in the intermediate state. The model describes fairly well the unpolarized
cross section obtained earlier by us and the analyzing power at 0.8 GeV, it
fails to reproduce the angular dependence of at 0.5 GeV.Comment: 4 pages, 4 figures, 1 tabl
Ab initio Hartree-Fock Born effective charges of LiH, LiF, LiCl, NaF, and NaCl
We use the Berry-phase-based theory of macroscopic polarization of dielectric
crystals formulated in terms of Wannier functions, and state-of-the-art
Gaussian basis functions, to obtain benchmark ab initio Hartree-Fock values of
the Born effective charges of ionic compounds LiH, LiF, LiCl, NaF, and NaCl. We
find excellent agreement with the experimental values for all the compounds
except LiCl and NaCl, for which the disagreement with the experiments is close
to 10% and 16%, respectively. This may imply the importance of many-body
effects in those systems.Comment: 11 pages, Revtex, 2 figures (included), to appear in Phys. Rev. B
April 15, 200
Beam-helicity asymmetries for single-hadron production in semi-inclusive deep-inelastic scattering from unpolarized hydrogen and deuterium targets
A measurement of beam-helicity asymmetries for single-hadron production in
deep-inelastic scattering is presented. Data from the scattering of 27.6 GeV
electrons and positrons off gaseous hydrogen and deuterium targets were
collected by the HERMES experiment. The asymmetries are presented separately as
a function of the Bjorken scaling variable, the hadron transverse momentum, and
the fractional energy for charged pions and kaons as well as for protons and
anti-protons. These asymmetries are also presented as a function of the three
aforementioned kinematic variables simultaneously
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