Browsing by Author "Allahverdiyeva, Shabnam"

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Adsorptive Stripping Voltammetric Determination of Higenamine on a Boron-Doped Diamond Electrode Improved by the Use of an Anionic Surfactant
(Elsevier Science Sa, 2020) Allahverdiyeva, Shabnam; Pinar, Pinar Talay; Keskin, Ertugrul; Yunusoglu, Oruc; Yardim, Yavuz; Senturk, Zuhre
The present work describes the first electroanalytical investigation and a new voltammetric method for a cheap, rapid and simple determination of higenamine at a surface of mildly-oxidized boron-doped diamond electrode (at +1.6 V during 180 s). The oxidation of compound was strongly dependent on pH. The sensitivity of method was significantly improved in the presence of anionic surfactant, sodium dodecyl sulfate (SDS). The first oxidation peak was chosen for the electroanalytical determination of higenamine due to its higher sensitivity compared to the other two ones. By employing square-wave stripping mode, there was a linear dependence of the oxidation peak current at +0.75 V and higenamine concentration in the range of 0.5-30.0 mg L-1 (1.84 x 10(-6)-1.11 x 10(-4) M), with a detection limit of 0.13 mg L-1 (4.79 x 10(-7) M) in BR buffer pH 2.0 containing 2 x 10(-4) M SDS (after 30 s accumulation at open-circuit condition). As an example, the practical applicability of the proposed method was tested with the quantification of higenamine in the commercial dietary supplement formulations, with results in good agreement to those obtained declared by high-performance liquid chromatography with diode-array detection as a reference method.
Determination of Tramadol in Pharmaceutical Forms and Urine Samples Using a Boron-Doped Diamond Electrode
(Serbian Chemical Soc, 2020) Keskin, Ertugrul; Allahverdiyeva, Shabnam; Seyho, Esma; Yardim, Yavuz
The present work describes the electroanalytical investigation and a novel voltammetric method for the cheap, fast and simple quantification of tramadol (TRH) using a boron-doped diamond electrode. TRH displayed one well-defined, irreversible and adsorption-controlled oxidation peak at about 1.58 V (vs. Ag/AgCl) in Britton-Robinson buffer (BR, 0.1 mol L-1, pH 3.0) using the cyclic voltammetry technique. The voltammetric responses of the oxidation peaks are dependent on pH and their sensitivity was significantly enhanced in the presence of surfactant media (sodium dodecyl sulphate, SDS). Under the optimized experiment conditions, employing the square-wave stripping mode, it was found that there was an excellent correlation between oxidation peak current and the TRH concentration in the range 0.25 to 50.0 mu g mL(-1) (8.34 x 10(-7)-1.67 x 10(-4) mol L-1), with a detection limit of 0.072 mu g mL(-1) (2.40 x 10(-7) mol L-1) in 0.1 mol L-1 BR buffer (pH 3.0) solution comprising 8 x 10(-4) mol L-1 SDS at 1.52 V (after 30 s accumulation at open-circuit conditions). The developed approach could be used for the quantification of TRH in pharmaceutical formulations and spiked human urine samples with acceptable recoveries.
Electroanalytical Investigation and Determination of Hepatitis C Antiviral Drug Ledipasvir at a Non-Modified Boron-Doped Diamond Electrode
(Elsevier Science Sa, 2020) Allahverdiyeva, Shabnam; Keskin, Ertugrul; Pinar, Pinar Talay; Yunusoglu, Oruc; Yardim, Yavuz; Senturk, Zuhre
This study is about the use of the boron-doped diamond electrode pretreated electrochemically (anodic and subsequent cathodic) in the voltammetric determination of hepatitis C antiviral drug ledipasvir. Cyclic voltammetric measurements revealed that the compound yielded two well-separated irreversible oxidation peaks (P-A1 and P-A2) in acidic medium. The dependence of intensities of currents and potentials on electrode pretreatment, pH and nature of the supporting electrolyte, and other variables was investigated by square-wave voltammetry. Determination of ledipasvir was performed in Britton-Robinson buffer (pH 2.0) on the basis of both P-A1 and P-A2, which offered linear concentration ranges 0.5-60.0 mu g mL(-1) (5.6 x 10(-7)-6.8 x 10(-5) mol L-1) and 5.0-60.0 mu g mL(-1) (5.6 x 10(-6)-6.8 x 10(-5) mol L-1), respectively, with detection limits of 0.12 mu g mL(-1) (1.4 x 10(-7) mol L-1) and 0.76 mu g mL(-1) (8.6 x 10(-7) mol L-1). The practical applicability of developed methodology was tested by the assay of a fixed-dose combination tablet with sofosbuvir.
Electrochemical Determination of Flavonoid Fisetin in Commercial Dietary Supplements Using a Boron-Doped Diamond Electrode
(Wiley-v C H verlag Gmbh, 2023) Allahverdiyeva, Shabnam; Keskin, Ertugrul; Yoruk, Ibrahim; Yardim, Yavuz
For the first time, a boron-doped diamond electrode was utilized to quantitatively determine flavonoid fisetin (FST). Cyclic voltammetric studies have shown that the electrochemical oxidation of FST is irreversible and well-separated two peaks (P-A1 and P-A2) in 0.1 MHNO3 solution. The effects of electrode pretreatment, solution pH, nature of the supporting electrolyte, and instrumental variables on the peak current and potentials of the FST were investigated by square-wave voltammetry (SWV) and then optimum ones were determined. It was observed that the cathodically pre-treated BDD (CPT-BDD) electrode's performance was better than the other pre-treatment procedures for increasing the FST oxidation signal. Under optimized conditions and using the SWV technique, the response of the first anodic peak (P-A1) of the FST was proportional in a concentration range of 0.5-20.0 mu g mL(-1) (1.7x10(-6)-6.9x10(-5) mol L-1) with a detection limit of 0.08 mu gm L-1 (2.8 x 10(-7) mol L-1). Also, it was successfully demonstrated that the proposed method is applicable in commercial nutritional supplement formulations.
Electrooxidation of Tetracycline Antibiotic Demeclocycline at Unmodified Boron-Doped Diamond Electrode and Its Enhancement Determination in Surfactant-Containing Media
(Elsevier, 2021) Allahverdiyeva, Shabnam; Yardim, Yavuz; Senturk, Zuhre
In this paper, for the first time, the study of voltammetric determination of tetracycline antibiotic demeclocycline was conducted. The oxidation of compound was investigated using a commercially available boron-doped diamond electrode pretreated electrochemically (anodic and subsequent cathodic). Addition of anionic surfactant, sodium dodecylsulfate (SDS) and cationic surfactant, cetyltrimethylammonium bromide (CTAB) to the demeclocycline-containing electrolyte solution at pH 2.0 and 9.0, respectively, was found to improve the sensitivity of the stripping voltammetric measurements. Employing square-wave stripping mode (after 30 s accumulation at open-circuit condition) in Britton-Robinson buffer, the limits of detection were found to be 1.17 mu g mL(-1) (2.3 x 10(-6) M) for 4 x 10(-4) SDS-containing buffer solution at pH 2, and 0.24 mu g mL(-1) (4.8 x 10(-7) M) for 1 x 10(-4) CTAB-containing buffer solution at pH 9.0. The feasibility of the developed approach for the quantification of demeclocycline was tested in urine samples.
First Electroanalytical Investigation and Simple Quantification of a Thrombopoietin-Receptor Agonist Drug Eltrombopag in the Presence of Cationic Surfactant at a Non-Modified Boron-Doped Diamond Electrode
(Elsevier Science Sa, 2020) Allahverdiyeva, Shabnam; Calisir, Meryem; Keskin, Ertugrul; Yardim, Yavuz; Senturk, Zuhre
The present study describes the first electroanalytical investigation and the development of a novel voltammetric method for a sensitive, simple, fast, cheap and eco-friendly determination of eltrombopag (ELT). At a borondoped diamond electrode pretreated electrochemically (anodic and subsequent cathodic), the compound presented one or two oxidation steps at relatively low positive potentials within the pH range 6.0-12.0 by employing square-wave voltammetry. The sensitivity of the measurements was significantly enhanced with the positive effect of cetyltrimethylammonium bromide (CTAB) under the accumulation condition. In Britton-Robinson buffer pH 12.0 containing 2 x 10(-4) mol L-1 CTAB (after 30 s accumulation at open-circuit condition), there was a linear dependence of peak current at +0.19 V (vs. Ag/AgCl) and ELT concentration in the range of 0.1-12.5 mu g mL(-1) (2.3 x 10(-7)-2.8 x 10(-5) mol L-1) with a detection limit of 0.0125 mu g mL(-1) (5.7 x 10(-8) mol L-1). The developed approach could be used for ELT determination in commercial tablet formulations.
First Electroanalytical Methodology for the Determination of Hordenine in Dietary Supplements Using a Boron-Doped Diamond Electrode
(Wiley-v C H verlag Gmbh, 2019) Allahverdiyeva, Shabnam; Keskin, Ertugrul; Pinar, Pinar Talay; Yardim, Yavuz; Senturk, Zuhre
The present work describes the first electrochemical investigation and a simple, rapid and modification-free electroanalytical methodology for quantification of hordenine (a potent phenylethylamine alkaloid) using a boron-doped diamond electrode. At optimized square-wave voltammetric parameters, the observed oxidation peak current in 0.1 M HClO4 at +1.33 V (vs. Ag/AgCl) increased linearly from 5.0 to 100 mu g mL(-1) (3.0x10(-5)-6.1x10(-4) M), with detection limit of 1.3 mu g mL(-1) (7.8x10(-6) M). The applicability of the developed method was tested with the determination of hordenine in the commercial dietary supplement formulations.
First Electrochemical Evaluation of Favipiravir Used as an Antiviral Option in the Treatment of Covid-19: a Study of Its Enhanced Voltammetric Determination in Cationic Surfactant Media Using a Boron-Doped Diamond Electrode
(Elsevier, 2021) Allahverdiyeva, Shabnam; Yunusoglu, Oruc; Yardim, Yavuz; Senturk, Zuhre
Favipiravir, a promising antiviral agent, is undergoing clinical trials for the potential treatment of the novel coronavirus disease 2019 (COVID-19). This is the first report for the electrochemical activity of favipiravir and its electroanalytical sensing. For this purpose, the effect of cationic surfactant, CTAB was demonstrated on the enhanced accumulation of favipiravir at the surface of cathodically pretreated boron-doped diamond (CPT-BDD) electrode. At first, the electrochemical properties of favipiravir were investigated in the surfactant-free solutions by the means of cyclic voltammetry. The compound presented a single oxidation step which is irreversible and adsorption controlled. A systematic study of various operational conditions, such as electrode pretreatment, pH of the supporting electrolyte, concentration of CTAB, accumulation variables, and instrumental parameters on the adsorptive stripping response, was examined using square-wave voltammetry. An oxidation signal at around +1.21 V in Britton-Robinson buffer at pH 8.0 containing 6 x 10(-4) M CTAB allowed to the adsorptive stripping voltammetric determination of favipiravir (after 60 s accumulation step at open-circuit condition). The process could be used in the concentration range with two linear segments of 0.01-0.1 mg mL(-1) (6.4 x 10(-8-)6.4 x 10(-7) M) and 0.1-20.0 mg mL(-1) (6.4 x 10(-7)-1.3 x 10(-4) M). The limit of detection values were found to be 0.0028 mg mL(-1) (1.8 x 10(-8) M), and 0.023 mg mL(-1) (1.5 x 10(-7) M) for the first and second segments of calibration graph, respectively. The feasibility of developed methodology was tested to the analysis of the commercial tablet formulations and model human urine samples. (C) 2021 Elsevier B.V. All rights reserved.
First Report for the Electrochemical Investigation of a New Hiv Integrase Inhibitor Dolutegravir: Its Voltammetric Determination in Tablet Dosage Forms and Human Urine Using a Boron-Doped Diamond Electrode
(Elsevier Science Sa, 2021) Allahverdiyeva, Shabnam; Pinar, Pinar Talay; Yardim, Yavuz; Senturk, Zuhre
In this paper, for the first time, the study of electrochemical investigation and voltammetric determination of HIV integrase inhibitor dolutegravir was described. The effect of pretreatment (anodically or cathodically) of borondoped diamond electrode was investigated in detail on the stripping voltammetric performance for this compound. Dolutegravir presented one or two oxidation peaks within the pH range 2.0-12.0 by using both pretreated electrodes. Employing square-wave stripping mode on the surface of cathodically pretreated boron-doped diamond electrode (after 60 s accumulation at +0.3 V) in Britton-Robinson buffer at pH 10.0, there was a linear dependence of the peak current at +0.79 V (vs. Ag/AgCl, 3 M NaCl) and dolutegravir concentration in the range of 1.0-50.0 mu g mL(-1) (2.38 x 10(-6) -1.19 x 10(-4) M), with a detection limit of 0.26 mu g mL(-1) (6.20 x 10(-7) M). The applicability of the developed approach for the quantification of dolutegravir was tested in the commercial tablet formulations and model human urine samples.
First Report for the Electrooxidation of Antifungal Anidulafungin: Application To Its Voltammetric Determination in Parenteral Lyophilized Formulation Using a Boron-Doped Diamond Electrode in the Presence of Anionic Surfactant
(Wiley-v C H verlag Gmbh, 2022) Ozok, Hande Izem; Allahverdiyeva, Shabnam; Yardim, Yavuz; Senturk, Zuhre
In this paper, for the first time, the study of electrochemical oxidation and electroanalytical determination of anidulafungin (ANF), a semi-synthetic echinocandin with antifungal activity was conducted. For this purpose, a commercially available boron-doped diamond (BDD) electrode pretreated electrochemically (anodic and subsequent cathodic) was used. Employing cyclic voltammetry, the compound presented a single and irreversible oxidation step. The electrode process is controlled by a dual mechanism of diffusion and adsorption. A systematic study of various experimental conditions, such as the effect of electrode pretreatment, pH and the nature of the supporting electrolyte, surfactant, accumulation variables, and instrumental parameters on the adsorption behavior of ANF, was carried out by using square-wave voltammetry. When the stripping mode (after 90 s accumulation at +0.3 V) was applied in 0.1 mol L-1 HNO3 containing 3x10(-4) mol L-1 SDS, there was a linear dependence between the oxidation peak current at +1.29 V and the ANF concentration in the range from 0.1 to 10.0 mu g mL(-1) (8.8x10(-8)-8.8x10(-6) mol L-1). The limit of detection value was found to be 0.021 mu g mL(-1) (1.8x10(-8) mol L-1). Practical applicability of the proposed method was demonstrated in commercial parenteral dosage form.
Simple and Rapid Voltammetric Determination of Cephalosporin Drug Cefixime on Boron-Doped Diamond Electrode
(Springer Wien, 2019) Keskin, Ertugrul; Allahverdiyeva, Shabnam; Seker, Hamza; Yardim, Yavuz
A boron-doped diamond electrode was used for the first time in sensitive and selective analysis of cefixime, a third-generation cephalosporin drug, using the square-wave voltammetry technique. The effect of the pretreatment procedure on the current response at the electrode was investigated. The best signals were obtained by polishing the electrode with a polishing pad after applying anodic and cathodic electrochemical pretreatment to the electrode. Cefixime gave a well-defined, irreversible and diffusion-controlled oxidation peak in 0.1 mol dm(-3) H2SO4 support electrolyte at + 1.25 V (vs. Ag/AgCl 3 mol dm(-3) NaCl). Under the best instrumental conditions and with the pretreatment procedure, a calibration curve was obtained with linearity between 2.2x10(-6) mol dm(-3) and 1.3x10(-4) mol dm(-3) at 5.9x10(-7) mol dm(-3) detection limit. The effect of possible interference substances on the current response for cefixime was investigated and the method was found to have sufficient selectivity. The developed method was successfully applied for the analysis of cefixime from pharmaceutical formulations. The method can be an alternative to the other analytical approaches due to its speed, simplicity, low cost, wide calibration range, and repeatable responses. [GRAPHICS] .
A Simple Approach To Simultaneous Electroanalytical Quantification of Acetaminophen and Tramadol Using a Boron-Doped Diamond Electrode in the Existence of Sodium Dodecyl Sulfate
(Wiley-v C H verlag Gmbh, 2020) Yunusoglu, Oruc; Allahverdiyeva, Shabnam; Yardim, Yavuz; Senturk, Zuhre
The present work describes the individual, selective and simultaneous quantification of acetaminophen (ACP) and tramadol hydrochloride (TRA) using a modification-free boron-doped diamond (BDD) electrode. Cyclic voltammetric measurements revealed that the profile of the binary mixtures of ACP and TRA were manifested by two irreversible oxidation peaks at about +1.04 V (for ACP) and +1.61 V (for TRA) in Britton-Robinson (BR) buffer pH 3.0. TRA oxidation peak was significantly improved in the presence of anionic surfactant, sodium dodecyl sulfate (SDS), while ACP signal did not change. By employing square-wave stripping mode in BR buffer pH 3.0 containing 8x10(-4) mol L-1 SDS after 30 s accumulation under open-circuit voltage, the BDD electrode could be used for quantification of ACP and TRA simultaneously in the ranges 1.0-70 mu g mL(-1) (6.6x10(-6)-4.6x10(-4) mol L-1) and 1.0-70 mu g mL(-1) (3.3x10(-6)-2.3x10(-4) mol L-1), with detection limits of 0.11 mu g mL(-1) (7.3x10(-7) mol L-1) and 0.13 mu g mL(-1) (4.3x10(-7) mol L-1), respectively. The practical applicability of the proposed approach was tested for the individual and simultaneous quantification of ACP and/or TRA in the pharmaceutical dosage forms.
Voltammetric Quantification of a Nonsteroidal Anti-Inflammatory Agent Diflunisal Based on the Enhancement Effect of Cationic Surfactant on Boron-Doped Diamond Electrode
(Soc Chemists Technologists Madeconia, 2021) Keskin, Ertugrul; Allahverdiyeva, Shabnam; Alali, Amer; Yardim, Yavuz
The present work describes a simple, fast and inexpensive voltammetric method for diflunisal measurement using a non-modified boron-doped diamond (BDD) electrode. The oxidation of the agent was irreversible and was a diffusion-controlled process. The sensitivity of the square wave voltammetric measurements were significantly improved when the cationic surfactant, cetyltrimethylammonium bromide (CTAB), was present in the supporting electrolyte solution. Using the square-wave mode, a linear response was obtained for diflunisal quantification in a 0.1 mol l(-1) phosphate buffer solution (pH 2.5) containing 5.10(-5) mol l(-1) CTAB at +1.07 V (vs. Ag/AgCl) (after 30 s accumulation under open-circuit conditions). Linearity was found for 0.05 to 2.0 mu g ml(-1) (2.0.10(-7) - 8.0.10(-6) mol l(-1)) with a detection limit of 0.013 mu g ml(-1) (5.2.10(-8) mol l(-1)). The developed approach could be used for the quantification of diflunisal in pharmaceutical formulations.
Voltammetric Quantification of the Anesthetic Drug Propofol (2,6-Diisopropylphenol) in Pharmaceutical Formulations on a Boron-Doped Diamond Electrode
(Serbian Chemical Soc, 2021) Keskin, Ertugrul; Allahverdiyeva, Shabnam; Ozok, Hande Izem; Yunusoglu, Oruc; Yardim, Yavuz
In this paper, the detailed electrochemistry of propofol (PRO), which is one of the intravenous agents commonly used for sedative-hypnotic purposes, was examined. In cyclic voltammetry, the agent showed one irreversible and diffusion-controlled oxidation peak, resulting in the formation of a couple with a reduction and re-oxidation wave at less positive potentials. The effect of electrode pretreatment procedures on the electrochemical response of PRO was investigated using square wave voltammetry (SWV) and the optimum procedure was used to improve the signal response in subsequent studies. Quantification of PRO was realized based on the first oxidation peak using SWV. After optimization of all variables, the linear working range of PRO was found to be between 2.5 mu g mL(-1) (1.4x 10 s mol L-1) and 160.0 mu g mL(-1) (1.1x 10(-3) mol L-1 , n = 15) with a detection limit 0.71 mu g mL(-1) (3.9 x 1 0(-6) mol L-1). No noteworthy interference effect was detected. Furthermore, the developed method was used for quantification of PRO in pharmaceutical samples.
Voltammetric Sensing of Dinitrophenolic Herbicide Dinoterb on Cathodically Pretreated Boron-Doped Diamond Electrode in the Presence of Cationic Surfactant
(Elsevier, 2020) Pinar, Pinar Talay; Allahverdiyeva, Shabnam; Yardim, Yavuz; Senturk, Zuhre
The present work describes the first anodic voltammetric investigation of dinitrophenolic herbicide dinoterb (DTB). For this purpose a commercially available boron-doped diamond electrode pretreated cathodically was applied. At first, the electrochemical properties based both on the oxidation and on the reduction of DTB were investigated by the means of cyclic voltammetry. To develop a voltammetric method for the determination of DTB, the anodic response corresponding to the oxidation of the phenolic moiety in the molecule was selected which was irreversible and exhibited adsorption controlled. A systematic study of various experimental conditions, such as electrode pretreatment, pH, nature of the supporting electrolytes, accumulation variables, and surfactant on the adsorptive stripping response, were examined by using square-wave voltammetry. An oxidation signal at around +1.22 V in Britton-Robinson buffer at pH 7.0 containing 5 x 10(-5) mol L-1 cetyltrimethylammonium bromide (cationic surfactant) allowed to the adsorptive stripping voltammetric determination of DTB (after 30 s accumulation step at open-circuit condition). The process could be used in the concentration range from 0.0075 to 0.75 mu g mL(-1) (3.12 x 10(-8)-3.12 x 10(-6) mol L-1) with a detection limit equal to 0.0022 mu g mL(-1) (9.16 x 10(-9) mol L-1). The feasibility of developed methodology was tested to the analysis of the spiked samples of river water and soil matrices with the satisfactory recoveries.