Wyniki wyszukiwania - Biblioteka Nauki

1

Electrooxidation of ketoconazole in acetonitrile and its determination in pharmaceutical preparations

100%

Shamsipur M. , Farhadi K.

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tom Vol. 46, No. 3

387-395

EN

Rotating disk voltammetry, cyclic voltammetry and controlled potential coulometry were employed to investigate the oxidation of ketoconazole (KG) at the surface of platinum (Pt) gold (Au) and glassy carbon (GC) electrodes in acetonitrile using tetra-butylammonium perchlorate as supporting electrolyte. The results revealed that KC is initially oxidized reversibly with the loss of one electron to the cation radical KC+, which decays gradually via a chemical reaction. KC can be further oxidized irreversibly at increased applied potential with the loss of the second electron to give some stable products. A differential pulse voltammetric method at a Pt electrode was developed for the determination of KC in the concentration range of 2.0 x 10(-6)-2.0 x 10(-4)mol 1(-1). The procedure was applied to the determination of KC in its tablets and creams.

PL

Badano elektroutlenianie hetokonazolu na elektrodach platynowych, złotych i z węgla szklistego stosując woltamperometrię cykliczną i rolującego dysku oraz kulometrię przy stałym potencjale. Jako rozpuszczalnika użyto acetonitryl, a elektrolitem podstawowym był nadchloran tetrobutyloamoniowy. Wykazano, że pierwszy stopień utleniania był odwracalny i jednoelektronowy. Produkt tego etapu powoli zanikał w roztworze. Mógł być również dalej utleniony i wtedy tworzył stabilny produkt. Opracowano różnicową, pulsowąwoltamperometrycznąmetodę oznaczania ketokonazolu w zakresie stężeń 2.0 x 10(-6-2.0 x 10(-4) mol 1(-1). Metodę tę zastosowano do oznaczania tego związku w tabletkach i kremach.

2

Acid-base titrimetric determination of ketoconazole and miconazole in micellar media

100%

Shamsipur M. , Jalali F.

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tom Vol. 47, No. 6

905-911

EN

A simple and accurate pH-metric method is described for the determination of two sparingly soluble in water antifungal drugs: ketoconazole and miconazole. Cetyltrimethylammo-nium bromide and sodium dodecylsulfate micelles have been used to solubilize these compounds. The application of the proposed method to the analysis of pharmaceutical preparations of the related species gave satisfactory results. Simplicity and the absence of harmful organic solvents in this method makes it possible to be used in routine analyses.

PL

Opisano prostą i dokładną metodę pehametryczną oznaczania dwóch trudno rozpuszczalnych w wodzie leków przecigrzybicznych: ketokonazolu i mykonazolu. Do poprawy rozpuszczalności użyto bromku cetylotrimetyloamoniowego, oraz dodecylosiarczanu sodowego. Opracowaną metodę zastosowano z powodzeniem w analizie preparatów farmaceutycznych zawierających wyżej wspomniane związki. Metoda nadaje się do zastosowania w analizach rutynowych ze względu na prostotę i nieobecność szkodliwych rozpuszczalników organicznych.

3

Spectrophotometric study of thermodynamics and kinetics of charge-transfer complexation of dibenzopyridino-18-crown-6 with iodine in chloroform solution

100%

Zolgharnein J. , Shamsipur M.

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tom Vol. 72, nr 11

2486-2492

EN

The charge-transfer complexation reaction between iodine and dibenzopridino-18-crown-6 (DBPY18C6) has been investigated spectrophotomertically in chloroform solution at different temperatures. The resulting comlex was formulated as (DBPY18C6...I(+))I(-/3).The enthalpy and entropy of the complex formation were evaluated from the temperature dependence of the formation constant. The resulting charge-transfer complex is both enthalpy and entropy stabilized. The rate constants at various temperatures and the activation parameters were evaluated.

4

Conductance Study of the Thermodynamics of Dibenzopyridino-18-crown-6 Complexes with K+, Ti+, Sr2+ and Ba2+ Ions in Acetonitrile Solution

100%

Shamsipur M. , Tavakkoli N.

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2004

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tom Vol. 78 / nr 1

109-116

EN

The complexation reactions between dibenzopyridino-18-crown-6 and Tl+, K+, Sr2+ and Ba2+ ions were studied conductometrically in acetonitrile solution at various temperatures. The formation constants of the resulting 1:1 complexes were calculated from the computer fitting of the molar conductance-mole ratio data at different temperatures. At 25°C, the stability of the resulting complexes varied in the order Ba2+ > Sr2+ > Tl+ > K+. The enthalpy and entropy changes of the complexation reactions were evaluated from the temperature dependence of formation constants. While, the bivalent alkaline earth complexes are both enthalpy and entropy stabilized, the univalent cation complexes used are enthalpy stabilized but entropy destabilized.

5

Micellar-enhanced spectrofluorimetric determination of ketoconazole in cetyltrilethylammonium bromide medium

80%

Jalali F. , Afshoon A. , Shamsipur M.

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tom Vol. 52, No. 1

115-123

EN

Fluorescence of ketoconazole at 370 nm has been found to be greatly enhanced in miceilar solutions of cetyltrimethylammonium bromide (CTAB). Under optimum conditions (0.05 mol L-1 CTAB and pH 7.2), ketoconazole was determined in the concentration range 0.02-10 mg L-1 (3.76 x 10-8mol L-11.88 x 10-1 mol L-1), detection limit was 0.02 mg L-1 (3.76 x 10-8 mol L-1)' The method was successfully applied to the determination of low- concentrations of ketoconazole in pharmaceutical preparations and blood serum sample.

PL

Stwierdzono, że fluorescencja ketokonazolu przy 370 nm ulega znacznemu wzmocnieniu w micelarnych roztworach bromku cetylotrimetyloamoniowego (CTAB). W optymalnych warunkach (0,05 mol L-1 CTAB, pH 7,2) ketokonazol został oznaczony w zakresie stężeń 0.02-10 mg L-1 (3.76 x10-8mol L-11,88 x 10"5 mol L-1), granica wykrywalności 0,02 mg L-1 (3.76 x 10-5 mol L-1). Metodę z powodzeniem zastosowano do oznaczania niskich stężeń ketokonazolu w preparatach farmaceutycznych i w próbkach krwi.

6

Study of Permanganate Ion Transfer Across an Electrified Water/Nitrobenzene Interface

80%

Heli H. , Shamsipur M. , Mousavi M.

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2006

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tom Vol. 80, nr 2

313-323

EN

The transfer of permanganate anion across a water/nitrobenzene interface has been studied by cyclic voltammetry and chronopotentiometry techniques. The diffusion coefficient of the species in aqueous phase was obtained by means of both cyclic voltammetry (DW = 2.75x10-5cm2 s-1) and chronopotentiometry (DW = 2.79x10-5cm2 s-1). The standard potential of transfer was obtained as deltaE0' = -198 mVand the transfer coefficient has also been calculated from the Tafel slope as alfa = 0.4. The effect of temperature on the ion transfer process was studied over a wide range (10-70 graduate C). The Gibbs activation energy of the ion transfer across the interface (deltaG = 12.09 kJ mol-1) and the Gibbs activation energy of ion transport in the bulk of aqueous solution (deltaG = 12.58 kJ mol-1) have been obtained from the temperature dependence of transfer rate data.

7

Complexation Study of UO2 2+ Ion with 18-Crown-6, Dicyclohexyl-18-crown-6 and Dibenzo-18-crown-6 in Binary Nitromethane-Acetonitrile Mixture by a Competitive NMR Technique Using 7 LI Nucleus as a Probe

80%

Karkhaneei E. , Zebarjadian M. , Shamsipur M.

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tom Vol. 77 / nr 2

227-235

EN

Lithium-7NMRmeasurements were used to determine the stability of 1:1 Li+ complexes with 18-crown-6 (18C6), dicyclohexyl-18-crown-6 (DC18C6) and dibenzo-18-crown-6 (DB18C6) in various binary nitromethane-acetonitrile mixtures.Acompetitive 7LiNMR technique was also employed to probe the complexation of UO2 2+ ion with these crown ethers in the mixed solvents used. In all solvent mixtures, the stability of the resulting 1:1 complexes was found to decrease in the order DC18C6 > 18C6 > DB18C6. There is an inverse relationship between the complex stability and the amount of acetonitrile in the mixed solvents.

8

Conductance Study of Complexation of Ammonium and Alkylammonium Ions with Some Aza-Substituted Crown Ethers in Binary Acetonitrile-Dimethylsulfoxide Mixtures

80%

Hasani M. , Darabi M. , Shamsipur M.

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tom Vol. 77 / nr 3

345-354

EN

A conductance study of the interaction between ammonium and four different alkylammonium ions and dibenzodiaza-15-crown-4 (DBDA15C4), diaza-18-crown-6 (DAl8C6), aza-18-crown-6 (A18C6) and dibenzyldiaza-18-crown-6 (DBzDAl8C6) in acetonitrile-dimethylsulfoxide mixtures was carried out at 25_C. The formation constants of the resulting l:l complexes were determined from the molar conductance-mole ratio data and, in the case of all cations used, found to vary in the order DBDAl5C4 > DAl8C6 > A18C6 > DBzDAl8C6. In all cases, the substitution of alkyl groups on the ammonium ion is found to decrease the stability of the resulting macrocycles' complexes, the sequence of which being NH4 + >MeNH3 + > EtH3 + > Et NH 2 2 + > Et3NH+. The stability of all complexes in the binary mixtures used was found to decrease with increasing mole fraction of dimethylsulfoxide.

9

Silver selective PVC-membrane sensors with and without graphite based on C-methycalix[4]resorcareneoctamethyl ester

71%

Shamsipur M. , Rouhani S. , Mohajeri A. , Ganjali M. R. , Poursaberi T.

Chemia Analityczna

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2003

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tom Vol. 48, No. 6

947-958

EN

Novel polymeric membrane (PME) and coated graphite (CGE) silver-selective electrodes based on a calix[4]resorcareneoctamethyl ester has been prepared. The electrodes revealed Nemstian behaviour over a wide Ag+ion concentration range (1.0 x 10'5-1.0 * 10 ' mol L"' for PME and 1.0 * 1.0-10(-7) x 10(-1) mol L(-1) for CGE) with very low detection limits (4.7 x K)(-6) mol L(-1) for PME and 8.5 x 10(-8) mol L(-1) for CGE). They occurred to be very selective towards Ag+ even in the presence of other numerous cations. Their responses were independent of pH within the range of 4-9. The electrodes can be used for at least 3 months without any considerable potential deviations. They served as indicator electrodes in poten-tiometric titration of silver ion.

PL

Spreparowano nowe, selektywne w stosunku do srebra elektrody z polimerową membraną (PME) zawierające ester kaliks[4]rezorkarenooktametylowy. W jednym rozwiązaniu konstrukcyjnym matrycę PCV nakładano na grafit. Elektrody spełniają prawo Nersta w szerokim zakresie stężenia jonów Ag+(l,O x 10(-5)-l,0x 10(-1) 'mol L(-1) w przypadku PME i 1,0 x 10(-7)-1,0 x 10(-1) w przypadku CGE) przy bardzo niskiej granicy wykrywalności (4,7 x l 0(-6) mol L(-1) w przypadku PME oraz 8,5 x l 0(-8) mol L(-1) w przypadku CGE). Wykazują bardzo dobrą selektywność w stosunku do jonów srebra nawet w obecności wielu innych kationów. Ich odpowiedzi nie zależą od wartości pH w granicach 4-9. Elektrody mogą być używane co najmniej przez 3 miesiące bez widocznych zmian potencjału. Stosowano je jako wskaźnik w potencjometrycznym miareczkowaniu jonów srebra.

10

Differential Pulse Polarographic Study of Mercury Complexes with Some Substituted Pyrimidines in Binary Acetonitrile-Dimethylformamide Mixtures

71%

Maddah B. , Alizadeh K. , Shamsipur M. , Moghimi A. , Ganjali M.

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2006

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tom Vol. 80, nr 5

737-744

EN

The complex formation of Hg2+ ion with five synthesized substituted pyrimidines in binary acetonitrile-dimethylformamide (AN-DMF) mixtures was studied by differential pulse polarography at 25 graduate C. The stoichiometry and stability of the complexeswere determined by monitoring the shift in the Hg2+ differential pulse peak potential against the pyrimidines concentration. In all cases studied, itwas found that the stability of the resulting 1:1 complex decreases drastically by increasing the amount of dimethylformamide in the binary mixtures. The observed stability order in a given solvent mixture is discussed in terms of the solvating ability of the solvent, donor site number, and steric hindrance on the pyrimidines.

11

Differential Pulse Polographic Study of mercury Complexes with Some Benzo-Substituted macrocyclic Diamides in Binary Nitromethane+Dimethylformamide Mixtures

71%

Shamsipur M. , Fakbari A. R. , Sharghi H. , Eshghi H. , Ganjali M. R.

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2002

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tom Vol. 76 / nr 12

1665-1671

EN

The complex formation of Hg2+ ion with five recently synthesized benzo-substituted macrocyclic diamides in binary nitromethane + dimethylformamide mixtures was studied by differential pulse polarography at 25_C. The stoichiometry and stability of the complexes were determined by monitoring the shift in the Hg2+ differential pulse peak potential against the macrocycles concentration. In all cases studied, it was found that the stability of the resulting 1:1 complex decreases drastically by increasing the amount of dimethylformamide in the binary mixtures. The observed stability order in a given solvent mixture is discussed in terms of the cavity size, structural flexibility and nature of the substituted on the macrocyclic diamide ring.

12

Electrochemical studies of 1,8-dihydroxy-9,10-anthraquinone derivatives in acetonitrile

61%

Salimi A. , Tamaddon F. , Sharghi H. , Mousavi M. F. , Golabi S. M. , Shamsipur M.

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tom Vol. 72, nr 12

2573-2582

EN

The electrochemical reductions of some recently synthesized 1,8-dihydroxy-9,10-anthraquinone derivatives in acetonitrile were investigated. In the absence of proton donors, the anthraquinones reduced in two successive one-electron steps. The first step is reversible or nearly reversible, while the second step is quasireversible or irreversible, depending on the electrode used. The influence of molecular structure on the reduction potential is addressed. The diffusion coefficients of the anthraquinone derivatives were determined from chronoamperometric measurements on the GC, Au and Pt electrodes. The heterogeneous electron transfer rate constants and charge transfer diffusion coefficients were evaluated from rotating disc voltammetry measurements. Depedence of the rate constants on the anthraquinone structure and the electrode materials is discussed.

13

Different Complexation Behavior of a Proton Transfer Compound Obtained from Pyridine-2,6-dicarboxylic Acid and Creatinine with Tl(I), Cu(II), Fe(III) and Bi(III): Synthesis, Characterization, Crystal Structures and Solution Studies

51%

Aghabozorg H. , Ramezanipour F. , Soleimannejad J. , Sharif M. A. , Shokrollahi A. , Shamsipur M. , Moghimi A. , Attar Gharamaleki J. , Lippolis V. , Blake A. J.

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tom Vol. 82, nr 3

487-507

EN

The different complexation methods of a proton transfer compound, (creatH)(pydcH)źH2O (pydcH2 = pyridine-2,6-di carboxylic acid; creat = creatinine) with metal ions have been studied and formation of [(Tl(pydcH)]n (1), [(Fe(pydc)(H2O)2)2ox]ź6H2O (2), [Cu(pydc)(pydcH2)]ź2H2O (3) and (creatH)2[Bi(pydc)2]2ź4H2O (4) are re ported. The characterization was performed using IR spectroscopy and single crystal X-ray diffraction analysis. The Tl(I) complex [(Tl(pydcH)]n (1) obtained from (creatH)(pydcH)źH2O is a polymeric system, showing only the contribution of the anionic species of (creatH)(pydcH)źH2O to the complexation. The Fe(III) and the Cu(II) complexes [(Fe(pydc)(H2O)2)2ox]ź6H2O (2) (ox = ox a late) and [Cu(pydc)(pydcH2)]ź2H2O (3) were also obtained from (creatH)(pydcH)źH2O. The Bi(III) complex (creatH)2[Bi(pydc)2]2ź4H2O (4) is a dimeric system, showing both contribution of the cationic and anionic fragments. The complexes 1-4 show a variety of structural features including mononuclear, binuclear, polymeric structures and unusual ligand formation. In compounds (1), (2), (3) and (4), a large number of hydrogen bonds are observed. These interactions as well as p-p stacking play an important role in the formation and stabilization of supra molecular systems in the crystal lattices. The stoichiometry and stability of the Cu(II), Tl(I) and Bi(III) complexes with (pydc)(creat) and Fe(III) with pydc-ox mixture in aqueous solution were investigated by potentiometric pH titration.