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Open access

Silvia Imre, Klára Kacsó and Daniela-Lucia Muntean

Abstract

Introduction: This study proposes the simultaneous determination of atorvastatin and amlodipine in industrial tablets by a quantitative spectrophotometric method, named the apparent content curve method, test method, and by an HPLC method with UV detection as reference method.

Materials and methods: A synthetic mixture and two fixed medicinal combinations containing amlodipine and atorvastatin were investigated by the apparent content curve method, a simple and relatively inexpensive UV-VIS spectrophotometric method based on a mathematical approach derived from the Lambert-Beer law. The results were compared with those obtained by an HPLC method.

Results: A good correlation of the results was obtained, the difference between the pair results was not significant (p >0.05).

Conclusions: The proposed spectrophotometric method is an easier and cheaper alternative for the quantitative determination of amlodipine and atorvastatin in industrial fixed-dose combinations.

Open access

Ion Valentin, Imre Silvia, Cârje Anca Gabriela and Muntean Daniela Lucia

Abstract

Introduction: Perindopril, as an angiotensin converting enzyme inhibitor and indapamide, as a thiazide like diuretic, can be administrated together for the treatment of high blood preasure and other cardiovascular diseases. The aim of this study was to develop two simple and reliable separation methods for perindopril and indapamide by high performance liquid chromatography and capillary zone electrophoresis in order to evaluate their behaviour under separation conditions, for simultaneous separation.

Materials and methods: Standard solutions of perindopril erbumine and indapamide in proper solvents were analized. An Agilent 1100 series HPLC system was used for the separation of the two analytes on a C18 stationary phase (Zorbax Stable Bond 3.5 µm), under an isocratic elution. As a comparative method, an Agilent 7100 series capillary electrophoresis system was used for the development of the electrophoretic method.

Results: Both developed methods turned to comply to the separation performance parameters such as resolution and selectivity, with low limits of detection, wide range of liniarity. No statistical difference concerning precision of the qualitative parameters was observed. Time analysis less than 5 minutes both for chromatographic and electrophoretic separations proved to generate cost and time effective analysis methods.

Conclusions: Two analytical methods, HPLC and CZE respectively, for the separation of perindoprile erbumine and indapamide have been successfully developed, both recording satisfactory analytical parameters.

Open access

Rusu Aura, Imre Silvia, Mircia Eleonora and Hancu Gabriel

Abstract

Objective: Antibacterial quinolones represent an important class of pharmaceutical compounds that are widely used in therapy. Analytical methods that rely on their property to absorb light in the UV range are commonly used for their analysis. In the current study we present an interpretation of the relationship between chemical structure – UV spectra based on the comparative examination of UV spectral behavior of the eighteen quinolone derivatives and four model compounds.

Methods: Eighteen quinolone derivatives and four model compounds were selected and their UV spectra were recorded in different solvents (methanol, 0.1M HCl, 0.1M NaOH).

Results: The studied compounds show three absorption maximum values located around 210-230 nm, 270-300 nm and 315-330 nm values. A general characteristic was observed as the absorption bands exhibited both hypsochrome and bathochrome shifts, by comparison in different solvents. Most commonly we observed a slight hypsochrome shift at acidic pH (protonated form prevails) and basic pH (anionic form prevails). The structural differences are reflected in changes of UV spectra only when there are auxochrom substituents or different basic substituents are present in the quinolones structure.

Conclusions: The correlations between the chemical structure of quinolone derivatives and their UV spectra using model compounds were established. This study provides useful information that can be used successfully in various UV spectrophotometric analysis methods or in more complex analytical methods using UV detection, and also in pharmacodynamic and kinetic studies.

Open access

Alina Balint, Anca Gabriela Cârje, Daniela Lucia Muntean and Silvia Imre

Abstract

Objective: The aim of the study was to compare the influence of mobile phase composition and temperature on chiral separation of racemic ibuprofen by capillary electrophoresis and high performance liquid chromatography with UV detection. Materials and methods: Racemic ibuprofen was analysed on a chiral OVM column with an HPLC system 1100 Agilent Technologies, under isocratic elution, by using potassium dihydrogen phosphate 20 mM and ethanol in mobile phase. The flow rate was set at 1 mL/min, UV detector at 220 nm and different column temperatures were tested. For electrophoresis separation an Agilent CE G1600AX Capillary Electrophoresis System system, with UV detection, was used. The electrophoresis analysis was performed at different pH values and temperatures, with phosphate buffer 25 mM and methyl-β-cyclodextrin as chiral selector. Results: The chromatograhic analysis reveals a high influence of mobile phase pH on ibuprofen enantiomers separation. An elution with a mixture of potassium dihydrogen phosphate 20 mM pH=3 and ethanol, at 25°C, allowed enantiomers separation with good resolution in less than 8 min. Conclusions: The proposed HPLC method proved suitable for the separation of ibuprofen enantiomers with a good resolution, but the capillary electrophoresis tested parameters did not allow chiral discrimination.

Open access

Anca Gabriela Cârje, Alina Balint, Daniela-Lucia Muntean, Gabriel Hancu, Valentin Ion and Silvia Imre

Abstract

Objective: The purpose of this study was to separate the enantiomers of amlodipine by High Performance Liquid Chromatography (HPLC) using ovomucoid (OVM) as chiral selector, respectively by Capillary Electrophoresis (CE) using cyclodextrines and to evaluate the analytical performance of the both proposed methods.

Material and methods: HPLC enantioseparation of amlodipine was performed on an HPLC Agilent Technologies 1100 series using as chiral stationary phase an Ultron ES OVM, 150x4.6 mm column with ovomucoid as chiral selector. The stereoselective CE analysis of amlodipine was achieved on Agilent Technologies 7100 CE using uncoated fused-silica capillaries 48 cm x 50 mm and different type of cyclodextrins as chiral selectors.

Results: A mobile phase consisting of 80% Na2HPO4 10 mM at a pH level of 5.0 and 20% ACN, isocratic elution at a flow of 1 ml/min turned to be the optimal experimental conditions for HPLC analysis (R=5.51; α=1.71) with retention times shorter than 10 minutes for the two isomers, tR (S-AML) = 4.63 (min); tR (R-AML) = 5.54 (min). The migration times for amlodipine enantiomers were tm (S-AML) = 8.15 (min) and tm (R-AML)= 8.45 (min) and the optimum CE conditions have proven to be a buffer solution containing 25 mM H3PO4 at pH 3.0 and 20 mM α-CD as chiral selector and a capillary temperature set at 15°C (R=1.51; α=1.03).

Conclusion: The analytical performances of the chromatographic method using OVM as chiral selector are superior to the electrophoretic analysis method but the CE method is more economical and may represent an alternative to the HPLC chromatographic separation.

Open access

Silvia Imre, Timea Haidu, Oana Ponta, Szende Vancea, Camil-Eugen Vari and Amelia Tero-Vescan

Abstract

Objective: The aim of the study was a comparative investigation by spectral and thermal analysis in order to asses a number of characteristics of different varieties ofrawmaterials of ursodeoxycholic acid and ibuprofen. The different dissolution behavior of two ursodeoxycholic acid pharmaceutical product by crystallinity pattern was investigated. Methods: Raw materials of ursodeoxycholic acid and ibuprofen were used. IR spectroscopy, differential scanning calorimetry and X-Ray Diffraction Analysis were applied. Results: The results show no crystallinitydifferences for different batches of the tested drugs. No solid solid transition was proved during sample preparation for transmission IR analysis. Conclusions: A combination of two more affordabletests by IR spectrometry and differential scanning calorimetry lead to the same results as X-Ray diffraction analysis for crystallinity similarity assessment of the studied substances. The dissolution differences of test drugs were not related to the polymorphism of the raw materials.

Open access

Amelia Tero-Vescan, Bianca-Eugenia Osz, Camil-Eugen Vari, Silvia Imre and Gabriel Hancu

Abstract

Objectives: The purpose of the study was to determine the omega-3/omega-6 ratio in swine brain homogenate by HPLC with UV detection and to discuss the values obtained by comparison to the human species. Materials and methods: Determinations were performed by HPLC method using as mobile phase an isocratic mixture (A:B - 5:95) of mobile phase A = 25% acetonitrile in water and B = acetonitrile with a flow-rate of 1.2 mL/min and UV detection at 205nm. Chromatographic column: Phenomenex C8 150x4.6 mm 5μm. 50 g swine brain was hydrolyzed with 100 mL 0.5N HCl, the organic phase was extracted in 50 mL hexane, concentrated by evaporation and resumed in 200 μL acetonitrile. Results: Polyunsaturated fatty acids were separated as follows arachidonic acid (AA) - Rt = 2.69 min, docosahexaenoic acid (DHA) - Rt = 3.12 min and eicosapentaenoic acid (EPA) - Rt = 3.97 min. The following omega-3/omega-6 ratios were calculated (DHA + EPA)/ AA = 0.572 ± 0.451, EPA/AA = 0.027 ± 0.015 and DHA/AA = 0.689 ± 0.612. Conclusions: The values obtained for these ratios should be balanced, but in reality they are in favor of the ratio denominator. Considering the physiological and nutritional similarities and that an accurate diagnosis of neurodegenerative disease is set in post-mortem, swine brain homogenate could serve as an animal model for human nervous tissue.

Open access

Amelia Tero-Vescan, Camil-Eugen Vari, Daniela-Lucia Muntean, Maria-Titica Dogaru, Cristina Filip and Silvia Imre

Abstract

A simple and selective method for genistein (GNST) determination in rat liver and kidney was validated in order to study the phytoestrogenic effect of GNST in ovariectomised female Wistar rats. GNST was separated on a Kromasil 100-RP8 column, 150 mm x 4.6 mm, 5 mm equipped with a Kromasil RP 8 precolumn. The mobile phase was 55:45 (v / v) phosphoric acid, 15 mmol in water: methanol at a flow rate of 1.3 ml / min. Luteolin 20 μg / ml in methanol was used as internal standard (IS). The retention time of GNST was tR = 13.22 min and tR =11.60 min for the IS. Calibration curves in the range 40-400 μg GNST/100g liver and 20-200 μg GNST/100g kidney presented a coefficient of determination higher than 0.99. The method developed presented a good precision and accuracy at the lower limit of quantification LLOQ. 10 white Wistar female rats, 8 weeks of age were treated s.c. with 10 mg GNST/kg bw/day for 8 weeks, while a group of 10 animals were used as controls. The values obtained for GNST in the liver were 192.12 ± 53.46 μg/100g and 74.51 ± 12.77 μg/100g in kidney samples.

Open access

Aura Rusu, Gabriel-Cosmin Popescu, Silvia Imre, Valentin Ion, Szende Vancea, Anda-Lavinia Grama, Hajnal Kelemen and Gabriel Hancu

Abstract

Objective: Silver complexes of antibacterial quinolones have the potential advantage of combining the antibacterial activity of silver and fluoroquinolones. The objective of our study was the preparation and the preliminary physico-chemical characterization of a silver complex with ofloxacin.

Methods: To achieve our goals several spectroscopic methods (ultraviolet spectrophotometry, mass spectrometry, and Fourier transform infrared spectroscopy) and thermal methods (differential scanning calorimetry and thermogravimetric analysis) were used in order to elucidate the chemical structure of the complex.

Results: Using mass spectrometry we established the stoichiometric ratio silver:ofloxacin as 1:2. Experimental data suggest a particular coordination for ofloxacin, as a monodentate ligand, in the formation of a complex with silver, through the nitrogen atom from the methyl-piperazine cycle.

Conclusions: The obtained complex has a chemical structure likely [Ag(Ofloxacin)2]NO3, requiring evaluation through other physico-chemical methods.