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71.
Biljana Nigovi? 《Analytical sciences》2004,20(4):639-643
The adsorptive and electrochemical behaviors of azithromycin were investigated on a glassy carbon electrode that was electrochemically treated by anodic oxidation at +1.8 V, following potential cycling in the potential range from -0.8 to +1.0 V. The resulting electrode showed good activity to improve the electrochemical response of the drug. An adsorptive stripping voltammetric method for the determination of azithromycin at an electrochemically activated glassy carbon electrode has been developed. Azithromycin was accumulated in phosphate buffer, pH 6, at a potential of +0.3 V (vs. Ag/AgCl electrode) for a certain time, and then determined by differential pulse voltammetry. The oxidative peak current at +0.82 V, at a scan rate of 20 mV s(-1), was a linear function of the concentration in the ranges of 0.25 - 2 microg mL(-1) and 1 - 10 microg mL(-1) using a 240 or 60 s(-1) preconcentration time, respectively. Application of the method to the determination of azithromycin in pharmaceuticals resulted in an acceptable deviation from the stated concentration. The preconcentration medium-exchange approach was utilized for the selective determination of the drug in spiked urine samples with satisfactory results. The peak current was linear with the drug concentration in the range of 0.5 - 3.5 microg per mL urine. The detection limit was 0.2 microg mL(-1) urine. The recovery levels of the method reached 96.3%. 相似文献
72.
73.
Biljana Otašević Svetlana Milovanović Mira Zečević Jelena Golubović Ana Protić 《Chromatographia》2014,77(1-2):109-118
A simple, rapid, isocratic, stability-indicating reverse phase ultra-performance liquid chromatographic (RP-UPLC) method was developed and validated for the routine analysis of moxonidine in the presence of its degradation products in active pharmaceutical ingredient and pharmaceutical dosage forms. Forced degradation studies were performed according to the guidance of International Conference for Harmonization and were used to evaluate moxonidine intrinsic stability. The drug was subjected to acid, neutral and base hydrolysis as well as to oxidative, thermal and photolytic decomposition in both solution and solid state. The drug appeared to be unstable towards acid and base hydrolysis. To achieve desirable conditions for UPLC analysis, the method development was done with the assistance of experimental design and multivariate optimization methodology by means of Derringer’s desirability function. Stress samples were analyzed according to the experimental plan for fractional factorial screening design and Box-Behnken optimization design. The chromatographic separation was achieved on a C18 Hypersil Gold aq. column (100 mm × 2.1 mm, 1.9 μm) with the mobile phase consisting of methanol–ammonium acetate buffer (10 mM, pH 3.43) mixture (0.9:99.1, v/v) pumped at a flow rate of 870 μL min?1 and detection wavelength of 255 nm. The UPLC–MS and UPLC–MS/MS analyses were further used to characterize the found degradation products. The validation of the proposed method was also performed considering selectivity, linearity, accuracy, precision, limit of detection and limit of quantification, and the results indicated that the method fulfilled all required criteria. The method was successfully applied to the analysis of commercial tablets. 相似文献
74.
75.
Adil Ehmedah Predrag Nedeljkovic Sanja Dacic Jelena Repac Biljana Draskovic-Pavlovic Dragana Vu
evi Sanja Pekovic Biljana Bozic Nedeljkovic 《Molecules (Basel, Switzerland)》2020,25(22)
Peripheral nerve injury (PNI) triggers a complex multi-cellular response involving the injured neurons, Schwann cells (SCs), and immune cells, often resulting in poor functional recovery. The aim of this study was to investigate the effects of the treatment with vitamin B (B1, B2, B3, B5, B6, and B12) complex on the interaction between macrophages and SCs during the recovery period after PNI. Transection of the motor branch of the femoral nerve followed by reconstruction by termino-terminal anastomosis was used as an experimental model. Isolated nerves from the sham (S), operated (O), and operated groups treated with the B vitamins (OT group) were used for immunofluorescence analysis. The obtained data indicated that PNI modulates interactions between macrophages and SCs in a time-dependent manner. The treatment with B vitamins complex promoted the M1-to M2-macrophage polarization and accelerated the transition from the non-myelin to myelin-forming SCs, an indicative of SCs maturation. The effect of B vitamins complex on both cell types was accompanied with an increase in macrophage/SC interactions, all of which correlated with the regeneration of the injured nerve. Clearly, the capacity of B vitamins to modulate macrophages-SCs interaction may be promising for the treatment of PNI. 相似文献
76.
Tiana Jovanovi Jadranka Miliki Nikola Cvjetianin Stevan Stojadinovi Biljana ljuki 《Electroanalysis》2020,32(8):1867-1874
Polarization curves and complex kinetics of oxygen reduction (ORR) and borohydride oxidation (BOR) reaction were evaluated at thin Au layer on Ti and TiO2 electrodes. TiO2 electrodes prepared included amorphous TiO2 (AM?TiO2) and anatase (A?TiO2). The electrodes structure and nanotube arrays morphology were observed by XRD and SEM, respectively. All electrodes show activity for both ORR and BOR. The use of Au layer over A?TiO2 produces the strongest synergistic effect for ORR with exchange of 3 electrons. On the other hand, the strongest effect for BOR was observed in case of Au/Ti. 相似文献
77.
Nina Radić Bratislav M. Obradović Mirjana Kostić Biljana Dojčinović Markéta Hudcová Milorad M. Kuraica Mirko Černák 《Plasma Chemistry and Plasma Processing》2013,33(1):201-218
The aim of this study was to examine and compare the potentials of two different ambient air plasma treatments: volume dielectric barrier discharge and diffuse coplanar surface barrier discharge, for the activation of polypropylene (PP) nonwovens surface. This was done in order to enhance the deposition of gold nanoparticles (AuNPs) onto PP surface. AuNPs were attached onto PP surface from colloidal solution prepared without stabilizers. Scanning electron microscopy, atomic force microscopy, attenuated total reflection-Fourier transform infrared spectroscopy, water absorption, and AuNPs uptake were used to assess the surface changes due to the plasma treatment, and to evaluate the durability of the achieved treatment effects. Finally, as a very important aspiration of the research, antibacterial activity of AuNPs loaded PP nonwovens against pathogens Staphylococcus aureus and Escherichia coli was evaluated in vitro. The plasma modified PP nonwovens have highly improved wetting and sorption properties. The PP nonwovens loaded with 17–62 mg/kg AuNPs exhibit antibacterial activity against tested pathogens. Surprisingly, this activity was enhanced by the first sample rinsing. 相似文献
78.
Miroslav M. Ristić Biljana Č. Popović 《Annals of the Institute of Statistical Mathematics》2003,55(4):797-802
We define the bivariate first order stationary autoregressive process {(X
n
,Y
n
)} with uniform marginal distribution where {X
n
} and {Y
n
} are the two stationary sequences with uniformU(0, 1) marginal distributions. We also estimate the unknown parameters of the model. 相似文献
79.
A method for the determination of soluble lead in human teeth by potentiometric stripping analysis with constant inverse current in the analytic step (PSA-iR), is described. The metal ions were concentrated as their amalgams on the glassy carbon surface of a working electrode that was previously coated with a thin mercury film and then stripped by a suitable oxidant. This paper examined effect of various factors on the PSA-iR results including the electrolysis potential, the solution stirring rate, and the constant inverse current. Quantitative analysis was carried out by both standard addition and calibration curve methods; a good linearity was obtained in the concentration range from 5 to 25 μg/dm3. A detection limit of 0.64 μg/dm3 was obtained, with a 5.21% coefficient of variation. Results obtained for teeth were not significantly different from these obtained by flameless atomic absorption spectrophotometry (FAAS). 相似文献
80.
Biljana A CavicMichael Thompson 《Analytica chimica acta》2002,469(1):101-113
Acoustic wave devices have continued to gain attention as biosensor structures because of their relative ease of operation and sensitivity to interfacial biochemical events. In the present paper, we review the use of the thickness-shear mode device for the label-free detection of processes involving nucleic acid moieties that are imposed at the sensor-liquid interface. Following a concise discussion of the theory and technology connected to the operation of the sensor in liquids, we outline a number of protocols that have been adopted for the attachment of oligonucleotides to sensor surfaces, many of which have been employed in ultrasonic biosensing. The various categories of applications are then surveyed in some detail. By far, the largest group is the study of duplex formation at the sensor surface, involving a compendium of experiments involving complementary and mismatched sequences. Considerably less attention has been paid to the detection of interaction of surface-bound nucleic acids with small molecules such as specific-binding peptides and drugs.A comprehensive appraisal of the literature in this field strongly suggests that acoustic coupling phenomena are particularly sensitive to interfacial physical chemistry. Accordingly, acoustic shear wave technology offers unique advantages over other sensor configurations because of its ability to produce multidimensional information through the recording of various parameters obtained from acoustic network analysis. 相似文献