Browsing by Author "Ozok, Hande Izem"

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Developing an Electroanalytical Procedure for the Determination of Caffeic Acid Phenethyl Ester at a Boron-Doped Diamond Electrode by the Use of Cationic Surfactant Media
(Elsevier Science Sa, 2022) Barzani, Hemn A. H.; Ali, Hoshyar Saadi; Ozok, Hande Izem; Yardim, Yavuz
The aim of the present work is to describe voltammetric analysis of caffeic acid phenethyl ester (CAPE) by using a boron-doped diamond (BDD) electrode in the presence of the cationic surfactant. Using cyclic voltammetry, CAPE demonstrated a single well-defined, quasi-reversible, adsorption-controlled by oxidation and reduction peak at approximately +0.44 V & +0.22 V respectively, (vs. Ag/AgCl) in the Britton-Robinson buffer (BR, 0.04 mol L-1, pH 5.0). The obtained results showed that the oxidation peaks of CAPE are pH dependent (ranging from 2.0 to 6.0). The oxidation peak currents of CAPE were significantly increased by using cetyltrimethylammonium bromide (CTAB, cationic surfactant) in the selected supporting electrolyte. Under the optimum parameters of experiment, the linear relationship was found for CAPE determination in 0.04 mol L-1 BR buffer solution (pH 5.0) including 1 x 10(-4) mol L-1 CTAB at +0.41 V (vs. Ag/AgCl) (after 30 s accumulation at the open-circuit condition). The linear range was found with 0.01 to 1.0 mu g mL(-1) (3.5 x 10(-8)-3.5 x 10(-6) mol L-1) via the detection limit 0.0028 mu g mL(-1) (9.8 x 10(-9) mol L-1). The developed approach was used successfully to detect CAPE concentration in the model urine samples. To our knowledge, this is the first approach for electrochemically analyzing of CAPE.
Electroanalytical Investigation and Voltammetric Quantification of Antiviral Drug Favipiravir in the Pharmaceutical Formulation and Urine Sample Using a Glassy Carbon Electrode in Anionic Surfactant Media
(Tubitak Scientific & Technological Research Council Turkey, 2022) Akca, Zeynep; Ozok, Hande Izem; Yardim, Yavuz; Senturk, Zuhre
This work describes the electrochemical investigation of a promising antiviral agent, favipiravir (FAV) utilizing a nonmodified glassy carbon (GC) electrode, along with a unique voltammetric approach that can determine FAV with a good degree of accuracy, speed, and cost-effectiveness. Using cyclic voltammetry, the compound demonstrated a single well-defined and an irreversible oxidation peak at approximately +1.12 V (vs. Ag/AgCl) in Britton-Robinson (BR) buffer at pH 10.0. The synergistic effect of anionic surfactant, sodium dodecyl sulfate (SDS) on the adsorption ability of GC electrode remarkably increased the sensitivity of the stripping voltammetric measurements of FAV. Employing square-wave adsorptive stripping voltammetry at +1.17 V (vs. Ag/AgCl) (after 60 s accumulation at open-circuit condition) in BR buffer (pH 10.0) containing 3 x 10(-4) M SDS, the linear relationship is found for FAV quantification in the concentration from 1.0 to 100.0 mu g mL(-1) (6.4 x 10(-6)-6.4 x 10(-4) M) with a detection limit of 0.26 mu g mL-1 (1.7 x 10(-6) M). The proposed approach was used successfully to determine FAV in pharmaceutical formulations and model human urine samples.
The First Electroanalytical Study of Umifenovir (Arbidol) Used as a Potential Antiviral Drug for The Treatment of Sars-Cov a Voltammetric Quantification on The Boron-Doped Diamond Electrode by Using Anionic Surfactant Media
(Electrochemical Soc inc, 2023) Ozok, Hande Izem; Kiran, Musa; Yunusoglu, Oruc; Yardim, Yavuz
In this work, an electroanalytical procedure for sensing umifenovir (arbidol) by square wave adsorptive stripping voltammetry (SW-AdSV) was developed utilizing an anodically pretreated boron-doped diamond electrode. Measurements of umifenovir using cyclic voltammetry with phosphate buffer solution (PBS, 0.1 M, pH 2.5) revealed irreversible behaviour, adsorption-controlled as well as an ill-defined (+1.13 V, P-A1) and a well-defined (+1.47 V, P-A2) two oxidation peaks. Umifenovir oxidations depend critically on supporting electrolytes and pH. The second oxidation peak (P-A2) current of the umifenovir was enhanced by adding sodium dodecyl sulfate (SDS, anionic surfactant) in the chosen supporting electrolyte. Umifenovir was quantified using its second oxidation peak (P-A2) at about +1.39 V. Using the optimized condition, the oxidation peak current of P-A2 showed a linear relationship for umifenovir determination in the concentration range from 0.005 to 1.0 mu g ml(-1) (9.73 x 10(-9)-1.95 x 10(-6) M), with a detection limit of 0.0014 mu g ml(-1) (2.72 x 10(-9) M) in PBS (PH 2.5) with SDS. Finally, the developed approach was successfully utilized to determine umifenovir in the pharmaceutical formulation and urine samples. To the best of our knowledge, this is the first electroanalytical approach for voltammetric sensing of umifenovir.
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.
First Voltammetric Procedure for Sensing Synthetic Thyroid Hormone Liothyronine Sodium in Tablet Dosage Form Using Anionic Surfactant Media at a Boron-Doped Diamond Electrode
(Elsevier Science Sa, 2025) Ozok, Hande Izem; Keskin, Ertugrul; Yardim, Yavuz
In this study, the voltammetric sensing of liothyronine sodium (LT3Na) was assessed using a boron-doped diamond (BDD) electrode, which had undergone electrochemical pretreatment to improve its surface activity. Cyclic voltammograms of LT3Na revealed well-defined, single, irreversible behavior that is governed by a dual mechanism of adsorption and diffusion at around +1.16 V (vs. Ag/AgCl) in 0.1 mol L- 1 H2SO4 solution. The oxidation peaks of LT3Na were studied using various electrolyte solutions, including Britton-Robinson buffer (0.04 mol L- 1, pH 2-10), phosphate buffer (0.1 mol L- 1, pH 2.5 and 7.4), acetate buffer (0.1 mol L- 1, pH 4.7), and 0.1 mol L- 1 solutions of HNO3, H2SO4, and HClO4, by square wave adsorption stripping voltammetry. The results showed that the oxidation peaks of LT3Na were pH-dependent across the range of 5.0 to 9.0; however, the optimal peak was observed in the H2SO4 solution. Introducing a sodium dodecyl sulfate (anionic surfactant, SDS) into the working electrolyte enhanced the anodic peak currents of LT3Na. A linear correlation for the quantification of LT3Na was obtained at +1.05 V in a 0.1 mol L- 1 H2SO4 solution containing 4 x 10-4 mol L- 1 SDS, under optimized conditions (vs. Ag/AgCl) (using open-circuit condition in 30 s accumulation step). The linear range spanned from 0.5 to 30.0 mu g mL-1 (7.4 x 10- 7-4.5 x 10-5 mol L- 1), with a detection limit of 0.15 mu g mL-1 (2.2 x 10-7mol L- 1). The LT3Na concentration in the drug formulation was successfully quantized using this method. According to our knowledge, this is the initial study to present an electrochemical analysis of this compound.
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.