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Öğe A novel core-shell-based chromatographic method supported by ratio derivative spectrophotometry for the simultaneous determination of perindopril, indapamide, and amlodipine ternary mixtures(TUBİTAK, 2018) Karadurmuş, Leyla; Gümüştaş, Mehmet; Kurbanoğlu, Sevinç; Uslu, Bengi; Özkan, Sibel AyşılIn this work, ratio spectra of the frst derivative spectrophotometric and liquid chromatographic methods have been described for the frst time for the simultaneous determination of perindopril (PER), indapamide (IND), and amlodipine (AML) in dosage forms. For chromatographic separations several mobile phase compositions were tested for efcient separation with the use of a new column technology related to superfcially porous particles. Optimum chromatographic separation was achieved using a Kinetex C18 column (150 × 4.6 mm I.D. 5 ?m) at a flow rate of 1.5 mL min-1. The separation was carried out at 30 ° C and the diode array detector was adjusted to 215 nm. As a comparison, a spectrophotometric method depending on the frst derivative of the ratio spectra was developed. The frst derivative of the ratio amplitudes at 227.2 nm for PER, 269.4 nm for AML, 292.0 nm for IND were selected. The proposed methods were successfully applied for the simultaneous assay of the drug combination in pharmaceutical dosage forms and the methods were compared to each other in terms of Student t and F tests for the comparison of their accuracy and precision parameters. © 2018 TUBITAK. All rights reserved.Öğe A sensitive and selective RP-LC method for the simultaneous determination of the antihypertensive drugs, enalapril, lercanidipine, nitrendipine and their validation(2013) Kurbanoğlu, Sevinç; Gümüştaş, Mehmet; Uslu, Bengi; Özkan, Sibel AyşılA RP-LC method is presented, which is sensitive and selective for the simultaneous determination of enalapril-lercanidipine and enalapril-nitrendipine binary mixtures in their pharmaceutical dosage forms. The analyte peaks were detected using the LC method with the mobile phase ratio of methanol: water (70:30 v/v, pH 3.0) and a 1.0 mL min-1 flow rate. The detection wavelength was selected at 210 nm using photo diode array detector and column temperature was optimized to 30 C. Linearity was obtained at different concentration ranges for all working pharmaceutically active compounds between 0.5 and 25 ?g mL-1. The proposed methods were extensively validated according to USP 27 requirements and ICH guidelines. The methods were applied to the analysis of pharmaceutical dosage forms containing binary mixtures of enalapril-lercanidipine and enalapril-nitrendipine. Moreover, the proposed methods were applied for the degradation studies of the selected compounds. Degradation studies were conducted using stress conditions such as UV light, acidic and alkaline hydrolysis, oxidation and heat in oven, to evaluate the ability of the separation of the response of standard compounds from their degradation products. © 2013 Springer-Verlag Berlin Heidelberg.Öğe Carbon quantum dots co-catalyzed with multiwalled carbon nanotubes and silver nanoparticles modified nanosensor for the electrochemical assay of anti-HIV drug Rilpivirine(Elsevier B.V., 2019) Aftab, Saima; Kurbanoğlu, Sevinç; Özçelikay, Göksu; Karadaş Bakırhan, Nurgül; Shah, Afzal; Özkan, Sibel AyşılIn this study, a novel and sensitive voltammetric nanosensor has been developed for the first time, for the detection of Rilpivirine based on amine-functionalized multiwalled carbon nanotubes (NH 2 -fMWCNT) with Ag nanoparticles onto carbon quantum dots modified glassy carbon electrode. Scanning electron microscopy, cyclic voltammetry and electrochemical impedance spectroscopy (EIS) were employed for characterization of the modified electrode. The Rilpivirine showed two irreversible oxidation peaks at 1.20 V and 1.42 V, at all the investigated pH values. The cyclic voltammetry results demonstrated excellent electrocatalytic activity of the modified electrode toward the oxidation of Rilpivirine as endorsed by the enhanced current responses compared to bare electrode. The electrochemical catalytic activity was further utilized as a sensitive detection method for the investigation of the redox mechanism of Rilpivirine using differential pulse voltammetry (DPV). For experimental conditions optimization the influence of supporting electrolyte and pH was examined and 0.5 M H 2 SO 4 was selected as the best electrolyte for getting intense current signals of the target analyte. The relationship of anodic peaks potentials for peak 1 and peak 2 (E P1 and E P2 ) with pH values and scan rate was also studied. Scan rate results showed that the oxidation of Rilpivirine at the nanosensor surface occurs under adsorption controlled manner. Therefore, differential pulse adsorptive stripping voltammetric technique was employed for the determination of Rilpivirine. Optimum accumulation potential and time were found as 0 V and 60 s, respectively. Under these optimum conditions, response of Rilpivirine demonstrated a linear behavior in the concentration range from 1.00 × 10 ?9 to 7.00 × 10 -9 M, with a limit of detection value of 3.00 × 10 -11 M and 6.40 × 10 -11 M for peak 1 and peak 2 in aqueous medium containing 0.5 M H 2 SO 4 as supporting electrolyte, respectively. Interferences studies were achieved in the presence of 500 fold higher concentration of interfering agents to check the selectivity of the developed method. The designed method was successfully applied for the determination of Rilpivirine in biological fluids, urine and synthetic human serum as a real sample. The value of limit of detection were found to be 1.79 × 10 -10 M, 4.47 × 10 -10 M in serum samples, 5.26 × 10 -10 M and 8.27 × 10 -10 M in urine samples for peak 1 and peak 2, respectively. Recovery experiments were carried out to check the accuracy and precision of the designed method. Moreover, the repeatability, reproducibility and stability of the modified electrode in supporting electrolyte, serum and urine samples were investigated. © 2019 Elsevier B.V.Öğe Development and validation of a stability-indicating RP-LC method for the determination of anticancer drug epirubicin in pharmaceuticals(Taylor and Francis Inc., 2014) Kurbanoğlu, Sevinç; Bozal Palabıyık, Burçin; Gümüştaş, Mehmet; Şanlı, Senem; Uslu, Bengi; Özkan, Sibel AyşılIn the present paper, sensitive, rapid, and different analytical methodology was developed for the determination of anticancer drug epirubicin (EPR). The mixture of epirubicin and moxifloxacin as internal standard was separated on a reversed phase Waters Spherisorb ODS1 column (250mm × 4.6mm × 5mm) using acetonitrile/water (30:70 v/v) mixture containing 15 mM phosphoric acid as mobile phase at 0.6 mL min-1 flow rate and 30 C. Also degradation studies were conducted as stress conditions of UV light, acidic hydrolysis, alkaline hydrolysis, oxidation, and heat in oven (100°C), to evaluate the ability of the proposed method for the separation of EPR from its degradation products. The validated method suggests routine analysis of EPR in differently equipped laboratories. © 2014 Copyright Taylor & Francis Group, LLC.Öğe Electrochemical approach for the sensitive determination of anticancer drug epirubicin in pharmaceuticals in the presence of anionic surfactant(Editions de l'Academie Republique Populaire, 2013) Bozal Palabıyık, Burçin; Kurbanoğlu, Sevinç; Gümüştaş, Mehmet; Uslu, Bengi; Özkan, Sibel AyşılIn this research, sensitive, rapid, different electrochemical methods were developed for the determination of anticancer drug epirubicin. The aim of the study was to fully validated determination of epirubicin in pharmaceuticals, by means of electroanalytical methods. The detailed electrooxidative behavior of epirubicin was investigated using cyclic, differential pulse and square wave voltammetry at boron-doped diamond electrode. The possible oxidation mechanism was discussed. Surfactant effect was also examined using 1×10-3 M sodium dodecyl sulphate. The oxidation process was found nearly irreversible over the pH range studied and exhibited diffusion controlled electrode process. All experimental parameters have been optimized and the following studies were realized under the optimum conditions. The sensor used in this research is suitable for the analysis of the trace amounts of epirubicin in pharmaceuticals. The proposed methods were applied to commercial preparations and average percentage recovery was in good agreement between each other (differential pulse and square wave voltammetry).Öğe Erratum to: UPLC versus HPLC on drug analysis: advantageous, applications and their validation parameters(2013) Gümüştaş, Mehmet; Kurbanoğlu, Sevinç; Uslu, Bengi; Özkan, Sibel AyşılThe authors would like to call the reader’s attention to the fact that unfortunately there were several references faultily assigned in Table 1.Öğe Investigation of voltammetric behavior and electroanalytical determination of anticancer epirubicin via glassy carbon electrode using differential pulse and square wave voltammetry techniques(Editions de l'Academie Republique Populaire, 2015) Kurbanoğlu, Sevinç; Bozal Palabıyık, Burçin; Gümüştaş, Mehmet; Uslu, Bengi; Özkan, Sibel AyşılThe electrochemical oxidation of epirubicin was investigated using cyclic, differential pulse and square wave voltammetry at glassy carbon electrode. The aim of the study was to determine epirubicin levels in pharmaceuticals via electrochemical methods. The oxidation process was quasi-reversible over the pH range studied and exhibited diffusion controlled electrode process. All experimental parameters have been optimized under the optimum conditions. The oxidation peak current was linearly proportional to the concentration of epirubicin in the range of 2×10-7-3.6×10-5 M with a detection limit of 4.1×10-8 M and 4.9×10-8 M by differential pulse and square wave voltammetry, respectively. These unique properties make the sensor suitable for the analysis of the trace amounts of epirubicin in pharmaceutical preparations. The proposed methods were applied to commercial preparations. Differential pulse and square wave voltammetry techniques were compared with t-test and F-test.Öğe Modern Assay Techniques for Cancer Drugs: Electroanalytical and Liquid Chromatography Methods(Taylor and Francis Ltd., 2018) Kurbanoğlu, Sevinç; Karadaş Bakırhan, Nurgül; Gümüştaş, Mehmet; Özkan, Sibel AyşılIn the past decades, patients who have chemotherapy treatment have considerably increased number. At this point, the development of rapid precise, and reliable methods are very important to analyze cancer drugs from their dosage forms, animals or human biological samples. Among all the analytical methods, electrochemical methods hold an important position with their unique properties such as specificity in the biological recognition process, fast response, and their reliability and do not need a pretreatment process. Chromatographic methods are also used in a wide range of analytical applications for the analyses of anticancer drugs. The power of chromatography comes from its ability to separate a mixture of analytes and determination of their concentrations. Chromatographic techniques can mainly be divided into gas, liquid, and supercritical fluid chromatography. In the frame of this information, this review is aimed to provide basic principles of electroanalytical and high-performance liquid chromatography methods for the analysis of cancer drugs. In addition, some selected applications for electrochemistry-related techniques and high-performance liquid chromatography, for the determination of anti-cancer pharmaceuticals published in the last five years are also discussed. © 2018, © 2018 Taylor & Francis Group, LLC.Öğe Simultaneous determination and validation of some binary mixtures of antihypertensive drugs using ratio derivative spectrophotometric method(Maik Nauka Publishing / Springer SBM, 2014) Kurbanoğlu, Sevinç; Gümüştaş, Mehmet; Özkan, Sibel AyşılRatio derivative spectrophotometric technique is presented for the rapid, accurate and precise simultaneous determination of olmesartan medoxomil (OLM), hydrochlorothiazide (HCT), and zofenopril (ZOF) as well as HCT binary mixtures in their dosage forms. First derivative of the ratio spectra (DD1) by measurements using different amplitudes was used and calibration graphs were established for 0.5–12 mg/mL HCT and 0.5–20 mg/mL OLM and ZOF. This method depends on first derivative of the ratio spectra by division of the absorption spectrum of the binary mixture by a standard spectrum of one of the components and then calculating the first derivative of the ratio spectrum. The first derivative of the ratio amplitudes at 250.4 and 291.5 nm for OLM, 250.4 and 298.1 nm for ZOF and 231.8, 332.2, 232.3 and 280.4 nm for HCT were selected for the determination. The proposed methods were successfully applied for determining of both drug combinations (ZOF-HCT and OLM-HCT) in their synthetic mixtures and in pharmaceutical dosage forms. The described procedures are extensively validated, non-destructive and do not require any separation steps. © 2014, Pleiades Publishing, Ltd.Öğe Simultaneous estimation and validation of some binary mixtures of antihypertensive drugs by RP-LC methods using two new generation silica columns(Elsevier B.V., 2013) Kurbanoğlu, Sevinç; Gümüştaş, Mehmet; Özkan, A. S.Two reversed phase liquid chromatographic (RP-LC) techniques are presented for the rapid, accurate, precise, simultaneous determination of olmesartan-hydrochlorothiazide and zofenopril-hydrochlorothiazide binary mixtures in their dosage forms. The separation of these binary mixtures was carried out by using two new stationary phases that have different surface chemistries which were used for the first time in the determination of these binary mixtures. The analyte peaks were detected at 216nm. Linearity was obtained in different concentration ranges between 0.5 and 20?gmL-1 for all compounds. The proposed methods have been extensively validated and sample preparation, flow rate, run time of the analytical systems were at low levels. The proposed methods would decrease the consumption of organic solvents and reagents further safeguarding to our environment. © 2012 Elsevier B.V.Öğe UPLC versus HPLC on drug analysis: Advantageous, applications and their validation parameters(2013) Gümüştaş, Mehmet; Kurbanoğlu, Sevinç; Uslu, Bengi; Özkan, Sibel AyşılLiquid chromatography (LC) is a separation technique used in many different areas to aid the identification and quantification of substances in various matrices. LC techniques with various detection modes have been widely used for the sensitive and selective determination of trace amounts of pharmaceutical active compounds in biological samples and their dosage forms. A completely new system design with advanced technology has been developed, called ultra high performance liquid chromatography, which has evolved from high performance liquid chromatography. The application of LC methods to drug analysis introduces a powerful tool for therapeutic drug monitoring as well as for clinical research. The advantages of short turnaround time, method reliability, method sensitivity, and drug specificity justify the use of LC techniques for various groups of the drug active compounds. This review describes some of the principles of ultra high performance liquid chromatography and high performance liquid chromatography, validation of these methods, system suitability tests for the methods, and application of methods to pharmaceutical analysis in the last 3 years. © 2013 Springer-Verlag Berlin Heidelberg.
