Yazar "Selimoglu, Faysal" seçeneğine göre listele

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    Chromatographic Multivariate Calibration Approaches to the Simultaneous Quantification of Three Different Drugs in Effervescent Tablets
    (Colegio Farmaceuticos Provincia De Buenos Aires, 2019) Selimoglu, Faysal; Kadioglu, Yucel; Dinc, Erdal
    In this research paper, PCR and PLS calibration models were used for processing chromatographic data to get the simultaneous quantification of paracetamol (PAR), caffeine (CAF) and aspirin (ASP) in effervescent tablets. The chromatographic data of the calibration set and samples of analytes were obtained by measuring photodiode array (PDA) detection at a set of eight different wavelengths (245, 250, 255, 260, 265, 270, 275, and 280 nm). Chromatographic analysis was accomplished using an Acquity UPLC BEH Phenyl (50 x 2.1 mm id, 1.7 mu m) column and a mobile phase consisting of 0.1 M acetic acid and methanol (75:25, v/v) with a flow rate of 0.35 mL/min. The validation for the proposed multivariate chromatographic PLS and PCR approaches were accomplished by the analysis of the validation samples containing PAR, CAF, and ASP. Analysis results of chromatographic PLS and PCR techniques were compared to those of traditional ultra-performance liquid chromatography and then comparable results were reported.
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    PARAFAC and MCR-ALS approaches to the pKa determination of benzoic acid and its derivatives
    (Pergamon-Elsevier Science Ltd, 2021) Selimoglu, Faysal; Unal, Nazangul; Ertekin, Zehra Ceren; Dinc, Erdal
    In general, the identification of biological activities of a molecule requires the observation of its physicochemical characteristics with its molecular interactions in an organism. The acid-base ionization constant (or pKa) is one of the key parameters that shows the physicochemical behaviors of molecules used in pharmaceuticals, foods, cosmetics etc. Therefore, the development of new methods (or approaches) is necessary to get simple, rapid, inexpensive and reliable determination of the acidity constants of active and inactive ingredients used in commercial products. In this paper, new UV spectroscopic methods were developed for the first time, by applying parallel factor analysis (PARAFAC) and multivariate curve resolution-alternating least squares (MCR-ALS) to the pH-UV spectral data arrays for determining the pKa values of benzoic acid and its five derivatives (4-fluorobenzoic acid, thiosalicylic acid, anthranilic acid, phthalic acid, 4-aminobenzoic acid). The pH profiles obtained by the PARAFAC and MCR-ALS decomposition of the pH-UV data arrays were used for the quantitative estimation of the acid base ionization constants for the investigated compounds without classical titration procedure. We concluded that the proposed PARAFAC and MCR-ALS provided us an opportunity for simple and rapid pKa determination of relevant compounds, which have functional importance in pharmaceutical and food industries. (C) 2020 Elsevier B.V. All rights reserved.
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    Silver nanoparticle decorated graphene-based SERS electrode towards procalcitonin detection
    (Elsevier, 2023) Selimoglu, Faysal; Ayhan, Muhammed Emre
    Monitoring procalcitonin levels (PCT) is critical for early diagnosis of sepsis, chronic disease, COVID-19 and other time-dependent pathologic cases. In this work, silver nanoparticles (AgNps) doped graphene-based Surface-enhanced Raman scattering (SERS) electrode was demonstrated for the first time to rapid detection of PCT biomarkers. An excellent combination of AgNps and single-layer graphene (SLG) was achieved, resulting in effective SERS enhancement. Due to the smooth and large surface area of SLG, many antibody molecules bind to the surface of SERS electrode and interact with PCT protein. The SERS enhancement factors (EFs) for R6G and PCT protein molecules were calculated to be 1012 and 1.6 x 109, respectively. The limits of detection (LODs) for R6G and PCT protein molecules were reported to be 10-13 M and 4 ngmL-1, respectively. These high EFs and lower LODs indicate that the fabricated AgNp/Gr@ ITO SERS electrodes have perfect SERS performance. SERS studies showed that there is a perfect interaction between PCT protein and AgNps and SLG, which leads to the enhancement of electromagnetic mechanism (EM) and chemical mechanism (CM) in the fabricated SERS ma-terials. The developed eco-friendly SERS platform can provide reliable and sensitive test results, faster analysis compared to conventional biosensors, mobile applications and cost-effective clinical management.
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    Simultaneous Determination of the Acid Dissociation Constants of Phenolics by Multivariate Analysis of pH and Ultraviolet-Visible Spectrophotometric Measurements
    (Taylor & Francis Inc, 2021) Dinc, Erdal; Selimoglu, Faysal; Unal, Nazangul; Ertekin, Zehra Ceren
    In the development of new commercial products in the pharmaceutical and food industries, acid dissociation constant (K-a) values of active and inactive ingredients are important factors for the estimation of the biological activity. In this regard, new spectrophotometric approaches based on parallel factor analysis (PARAFAC) and multivariate curve resolution-alternating least squares (MCR-ALS) to pH-absorbance dataset are described for the simultaneous determination of the acid dissociation constants of the phenolics ferulic acid, 4-hydroxybenzoic acid, syringic acid, protocatechuic acid, vanillic acid, and isovanillic acid that have more than one dissociation equilibrium without using classical titration procedures. The acid dissociation constants were determined by the pH profiles obtained by bilinear MCR-ALS and trilinear PARAFAC decomposition of pH-ultraviolet and pH-ultraviolet-visible spectroscopic datasets of the phenolics. For the quantification of the acid dissociation constants with the MCR-ALS and PARAFAC approaches, the estimated spectral profiles provided an opportunity for the direct observation of the individual spectral bands of each phenolic without the use of additional software. The results showed that MCR-ALS and PARAFAC applications to spectrophotometric measurements at various pH values were alternatives for solving acid dissociation constant problems that cannot be determined by classical methods.
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    Spectrophotometric quantification of paracetamol and tramadol hydrochloride by chemometric calibration methods
    (Tubitak Scientific & Technological Research Council Turkey, 2023) Selimoglu, Faysal; Pinarcik, Nermin
    The results of UV spectrophotometric analysis were analysed using partial least squares (PLS) and principal component re-gression (PCR) techniques to allow simultaneous evaluation of tramadol hydrochloride (TRA) and p-acetaminophen (PAR) in tablets. A calibration set of 16 mixtures, each containing PAR and TRA in various amounts, was created using a 24-full fractional design. The absorbance data set for the calibration set were obtained between 215-280 nm ( increment & lambda; = 0.1 nm). Subsequently, the concentration and ab-sorbance sets were used to generate PCR and PLS calibrations. The ratio spectra-first derivative method was devised as a solution to the same problem to compare the outcomes of the chemometric methods used for the same experiment. After the proposed methods were shown to be accurate in the testing of validation samples, they were used in analysing commercial tablet samples. The analytical results showed that PCR and PLS methods can be used as alternative methods to high-performance liquid chromatography (HPLC). Correla-tion coefficients were determined for the working concentration range of 6-36 g.mL-1 for PAR and 4-22 g.mL-1 for TRA. The limits of detection and quantification were calculated as 0.9104 & mu;g.mL-1 and 3.0347 & mu;g.mL-1, respectively. The test results of the chemometric analyses and ratio spectra-first derivative method of the commercial tablet form are in agreement with the results of the one-way ANO-VA with a confidence interval of 95%. This study shows that the ratio spectra-first derivative method, PCR and PLS models based on spectrophotometric measurements are very useful and straightforward techniques for the quantitative resolution of a two-component pharmaceutical preparation, requiring little sample preparation and little time for analysis.
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    Thiochalcone substituted phthalocyanines for dye-sensitized solar cells: Relation of optical and electrochemical properties for cell performance
    (Taylor & Francis Ltd, 2018) Karaca, Huseyin; Sisman, Ilkay; Guzel, Emre; Sezer, Serdar; Selimoglu, Faysal; Ergezen, Bahar; Karaca, Meryem
    The new peripherally tetra-substituted metallophthalocyanines (MPcs, M=Zn, Co, Ni) bearing the chalcone, (E)-3-(4-hydroxyphenyl)-1-(thiophen-2-yl)prop-2-en-1-one, for dye-sensitized solar cells (DSSCs) were synthesized. FT-IR, H-1 NMR, C-13 NMR, and UV-Vis spectroscopy techniques were utilized for characterization of all the MPcs. Electrochemical, optical and photovoltaic properties of all the MPcs as sensitizers were examined. Electrochemical studies reveal that while the ZnPc (4) and NiPc (6) give only Pc ring-based redox reactions, the CoPc (5) shows redox reactions based on both the central metal and the ring due to the metal 3d orbitals lying between the Pc HOMO and LUMO. The DSSC based on 5 gave the lowest power conversion efficiency (0.51%), perhaps due to the presence of a redox active central metal ion in the core of the complex, which results in a decrease electron transfer in the device. However, cells based on the other complexes including redox inactive central metal ions, which cannot reduce electron transfer, showed reasonable power conversion efficiencies of 1.27% and 1.11% for 4 and 6, respectively. The slight difference between the efficiencies can be attributed to higher molar extinction coefficient and narrower band gap of 4 than 6, which ensure a higher photocurrent and broader light absorption in the visible region. [GRAPHICS] .