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TEKKELİ, ŞERİFE EVRİM

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ŞERİFE EVRİM
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Author: Tekkeli, Serife Evrim Kepekci ×

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Now showing 1 - 10 of 13
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    Spectrofluorimetric Methods for the Determination of Gemifloxacin in Tablets and Spiked Plasma Samples
    (2011-05-01) Tekkeli, Serife Evrim Kepekci; Onal, Armagan; TEKKELİ, ŞERİFE EVRİM
    Two new, sensitive and selective spectrofluorimetric methods have been developed for the determination of gemifloxacin (GFX) in tablets and spiked plasma samples. Gemifloxacin, as a primary amine compound, reacts with 7-chloro-4-nitrobenzofurazon (NBD-Cl) (for method A) and fluorescamine (for method B) which are a highly sensitive fluorogenic reagents used in many investigations. For method A, the reaction product was measured spectrofluorimetrically at 516 nm with excitation at 451 nm. The reaction proceeded quantitatively at pH 8.5, 80 A degrees C in 7 min. For method B, the method was based on the reaction between GFX and fluorescamine in borate buffer solution of pH 8.5 to give highly fluorescent derivatives that were measured at 481 nm using an excitation wavelength of 351 nm. The fluorescence intensity was directly proportional to the concentration over the range 40-200 ng mL(-1) and 100-1,200 ng mL(-1) for method A and B, respectively. Successful applications of the developed methods, for the drug determination in pharmaceutical preparations and spiked plasma samples, were performed.
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    Spectrofluorimetric determination of tobramycin in human serum and pharmaceutical preparations by derivatization with fluorescamine
    (2014-02-01) Tekkeli, Serife Evrim Kepekci; Onal, Armagan; Sagirli, Olcay; TEKKELİ, ŞERİFE EVRİM
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    Determination of atorvastatin in human plasma by magnetic solid-phase extraction combined with HPLC and application to a pharmacokinetic study
    (2016-01-01) Tekkeli, Serife Evrim Kepekci; Durmus, ZEHRA; Onal, Armagan; TEKKELİ, ŞERİFE EVRİM
    A simple and sensitive analytical procedure by solid-phase extraction method combined with high-performance liquid chromatography and using of graphene-magnetite nanomaterials as sorbent has been developed for the determination of atorvastatin in human plasma. A magnetic solid-phase extraction method as a simple, fast, and efficient extraction technique has been used for sample preparation. A solid nanocomposite material, graphene nanosheets decorated with magnetite nanoparticles, was used as a magnetic adsorbent and the adsorption process was optimized in this study. RP C18 column was used with mobile phase composed of acetonitrile-10mM orthophosphoric acid by isocratic elution with the flow rate of 1mLmin(-1). Fluorimetric detection was used by the excitation wavelength at 282nm and the emission wavelength at 400nm. It was found that the calibration curve was linear in the 30-150ngmL(-1). Limit of detection and limit of quantitation values were found to be 10 and 30ngmL(-1), respectively. The intra-day and inter-day relative standard deviation values were less than 5.27%. It has been concluded that the new developed method provides fast, simple, cost reduced, and sensitive assay for atorvastatin determination in human plasma. This method is also applied to a pharmacokinetic study.
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    LIQUID CHROMATOGRAPHIC ANALYSIS OF CAROTENOIDS IN FOODS
    (2019-06-01) Tekkeli, Serife Evrim Kepekci; DİNCEL, DEMET; Onal, Cem; Onal, Armagan; Sagirli, Olcay; DİNCEL, DEMET; TEKKELİ, ŞERİFE EVRİM
    Current scientific studies indicate that carotenoids (CRTDs) are beneficial for maintaining health and lowering the risk of different pathologies. Considering the increasing role of carotenoids in healthcare, determination of carotenoid content of foods become important. Mostly, the analytical procedures that are used for this aim, are based on extraction techniques followed by different analytical procedures, especially high performance liquid chromatography. In this publication, a review of various analytical techniques developed for the determination of carotenoids in different food commodities starting from 2006 up to now, has been presented.
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    PublicationOpen Access
    Development and validation of a HPLC method for the determination of benzo(a)pyrene in human breast milk
    (2017-04-01) Tekkeli, Serife Evrim Kepekci; Gazioglu, IŞIL; GAZİOĞLU, IŞIL; TEKKELİ, ŞERİFE EVRİM
    A simple analytical procedure was developed for the quantitation of benzo(a)pyrene in human breast milk using solid phase extraction (SPE) combined with high performance liquid chromatography. Before the chromatographic process, SPE, including C18 functional groups in silicagel cartridges, was conducted for sample preparation. A C18 column (100×4.6 mm id, 3 μm particle size) was used with acetonitrile:water (80:20) as the mobile phase at a flow rate 1mL/min at 30°C. Fluorimetric detection was performed for excitation and emission at 290 and 406 nm, respectively. It was observed that the calibration curve was linear over the range of 0.5-80 ng/mL. The limit of detection and limit of quantitation were found to be 0.5 and 1.07 ng/mL, respectively. Intraday and interday relative standard deviation values were less than 5.15%. Moreover, the newly developed method provides a fast, simple, cost effective, and sensitive assay to detect an important carcinogen substance, benzo(a)pyrene, in human breast milk.
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    Current HPLC Methods for Assay of Nano Drug Delivery Systems
    (2017-01-01) Tekkeli, Serife Evrim Kepekci; KIZILTAS, Mustafa Volkan; TEKKELİ, ŞERİFE EVRİM
    In nano drug formulations the mechanism of release is a critical process to recognize controlled and targeted drug delivery systems. In order to gain high bioavailability and specificity from the drug to reach its therapeutic goal, the active substance must be loaded into the nanoparticles efficiently. Therefore, the amount in biological fluids or tissues and the remaining amount in nano carriers are very important parameters to understand the potential of the nano drug delivery systems. For this aim, suitable and validated quantitation methods are required to determine released drug concentrations from nano pharmaceutical formulations.
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    PublicationOpen Access
    Development and Validation of Spectrophotometric Methods for the Determination of Rasagiline in Pharmaceutical Preparations
    (2013-01-01) Tekkeli, Serife Evrim Kepekci; Onal, Armagan; Bahadori, FATEMEH; TEKKELİ, ŞERİFE EVRİM; BAHADORİ, FATEMEH
    This study presents three simple, rapid, and accurate spectrophotometric methods for the determination of Rasagiline (RSG) in pharmaceutical preparations. The determination procedures depend on the reaction of RSG with chloranilic acid for method A, tetrachloro-1,4-benzoquinone for method B, and 7,7,8,8-tetracyanoquinodimethane for method C. The colored products were quantitated spectrophotometrically at 524, 535, and 843 nm for methods A, B, and C, respectively. Different variables affecting the reaction were optimized. Linearity ranges of the methods with good correlation coefficients (0.9988-0.9996) were observed as 25-300 mu g mL(-1), 25-350 mu g mL(-1), and 50-500 mu g mL(-1) for methods A, B, and C, respectively. The formation of products takes place through different mechanisms. The sites of interaction were confirmed by elemental analysis using IR and H-1-NMR spectroscopy. The validation of the methods was carried out in terms of specificity, linearity, accuracy, precision, robustness, limit of detection, and limit of quantitation. No interference was observed from concomitants usually present in dosage forms. The methods were applied successfully to the determination of RSG in pharmaceutical preparations.
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    A Review of Current Methods for the Determination of Acrylamide in Food Products
    (2012-02-01) Tekkeli, Serife Evrim Kepekci; Onal, Cem; Onal, Armagan; TEKKELİ, ŞERİFE EVRİM
    Acrylamide (AA) is a potentially carcinogenic substance which is formed during heating of food products containing carbohydrates and asparagine. It was first detected in food products in 2002. Since that time, several analytical methods have been made available for the quantification of AA in various foods. Starting from the announcement in 2002, occurrence, formation, chemistry, toxicology, and potential health risk in the human diet have been investigated and methods of analysis have been reviewed in many articles. In this paper, current information and analytical methods for the determination of AA have been reviewed.
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    PublicationOpen Access
    Extractive Spectrophotometric Method for the Determination of Lamivudine and Zidovudine in Pharmaceutical Preparations Using Bromocresol Purple
    (2013-01-01) Tekkeli, Serife Evrim Kepekci; TEKKELİ, ŞERİFE EVRİM
    A new spectrophotometric method has been established for the quantitation of lamivudine (LVD) and zidovudine (ZVD) in pharmaceutical preparations. The method is based on the reaction between the investigated drug substances and bromocresol purple (BCP) producing ion-pair complexes in acidic buffers which are suitable for chloroform extraction. The maximum absorbance of these complexes was measured at 424 nm in chloroform. All variables were studied to optimize the reaction conditions. Linearity ranges were found to be 25-250 mu g mL(-1) for LVD-BCP and 50-300 mu g mL(-1) for ZVD-BCP. The developed method was successfully applied for the determination of these drugs in pharmaceutical preparations. Excipients in pharmaceutical formulations did not interfere in the analysis. The results were compared statistically with those obtained by the HPLC method reported in the literature. According to the results, the proposed method can be recommended for quality control and routine analysis.
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    PublicationOpen Access
    Development of an HPLC-UV Method for the Analysis of Drugs Used for Combined Hypertension Therapy in Pharmaceutical Preparations and Human Plasma
    (2013-01-01) Tekkeli, Serife Evrim Kepekci; TEKKELİ, ŞERİFE EVRİM
    A simple, rapid, and selective HPLC-UV method was developed for the determination of antihypertensive drug substances: amlodipine besilat (AML), olmesartan medoxomil (OLM), valsartan (VAL), and hydrochlorothiazide (HCT) in pharmaceuticals and plasma. These substances are mostly used as combinations. The combinations are found in various forms, especially in current pharmaceuticals as threesome components: OLM, AML, and HCT (combination I) and AML, VAL, and HCT (combination II). The separation was achieved by using an RP-CN column, and acetonitrile-methanol-10 mmol orthophosphoric acid pH 2.5 (7 : 13 : 80, v/v/v) was used as a mobile phase; the detector wavelength was set at 235 nm. The linear ranges were found as 0.1-18.5 μ g/mL, 0.4-25.6 μ g/mL, 0.3-15.5 μ g/mL, and 0.3-22 μ g/mL for AML, OLM, VAL, and HCT, respectively. In order to check the selectivity of the method for pharmaceutical preparations, forced degradation studies were carried out. According to the validation studies, the developed method was found to be reproducible and accurate as shown by RSD ≤6.1%, 5.7%, 6.9%, and 4.6% and relative mean error (RME) ≤10.6%, 5.8%, 6.5%, and 6.8% for AML, OLM, VAL, and HCT, respectively. Consequently, the method was applied to the analysis of tablets and plasma of the patients using drugs including those substances.