Browsing by Author "Altun, Ahmet"

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Investigation of the Electrochemical Properties of Benzo[K]fluorenthene Using a Glassy Carbon Electrode and Development of a Square-Wave Voltammetric Method for Its Quantification
(indian Acad Sciences, 2023) Altun, Ahmet; Yardim, Yavuz; Levent, Abdulkadir
The electrochemical behaviour of benzo[k]fluorenthene was studied using a bare glassy carbon electrode, cyclic voltammetry, and square wave voltammetry with a wide range of supporting electrolytes and a variety of pH values. An irreversible wave was generated due to adsorption-controlled diffusion at a potential of about +0.80 V at the glassy carbon electrode in benzo[k]fluoranthene BR medium with a pH of 3.0. Using the square-wave adsorptive voltammetry tecnhique, an extremely linear correlation was established between the anodic peak current and the concentration measured at the glassy carbon electrode in the BR medium with a pH value of 3.0. Using a glassy carbon electrode containing 80 mu M benzo[k]fluoranthene, the newly developed voltammetric technique was found to have a repeatability of 1.97% relative standard deviation. The voltammetric technique was applied to tap water samples without prior purification or separation steps. In this study, the results of the newly created voltammetric technique were evaluated together with those of chromatographic and spectroscopic analyses, which were found to be consistent with each other.
Sensitive Voltammetric Determination of Testosterone in Pharmaceuticals and Human Urine Using a Glassy Carbon Electrode in the Presence of Cationic Surfactant
(Pergamon-elsevier Science Ltd, 2014) Levent, Abdulkadir; Altun, Ahmet; Yardim, Yavuz; Senturk, Zuhre
In this work, the electrochemical investigation of testosterone, a steroid hormone from the androgen group, was carried out in aqueous and aqueous/surfactant solutions using a glassy carbon (GC) electrode. In cyclic voltammetry, the compound showed one irreversible and adsorption-controlled reduction peak. Addition of cationic surfactant (cetyltrimethylammonium bromide, CTAB) was found to enhance the reduction current signal of testosterone, whereas, anionic (sodium dodecylsulfate, SDS) and non-ionic (Tween 80) surfactants exhibited opposite effect. Using square-wave adsorptive stripping voltammetry, the current showed a linear dependence with concentration in the range between 10 and 70 nM in Britton-Robinson buffer, pH 5.0 containing 3 mM CTAB. A detection limit of 1.18 nM (0.34 ng mL(-1)), and relative standard deviation of 4.12% for a concentration level of 35 nM (n = 11) were calculated. This method was successfully applied for the analysis of testosterone in oil-based pharmaceutical preparations and urine samples without any separation. (C) 2013 Elsevier Ltd. All rights reserved.
Voltammetric Behavior of Testosterone on Bismuth Film Electrode: Highly Sensitive Determination in Pharmaceuticals and Human Urine by Square-Wave Adsorptive Stripping Voltammetry
(Wiley-v C H verlag Gmbh, 2015) Levent, Abdulkadir; Altun, Ahmet; Tas, Suleyman; Yardim, Yavuz; Senturk, Zuhre
In this paper, an electrochemical application of bismuth-film electrode (BiFE) fabricated via ex-situ electrodeposition onto a glassy carbon electrode for testosterone determination was investigated in aqueous and aqueous/surfactant solutions. In cyclic voltammetry, the compound showed one irreversible and adsorption-controlled reduction peak. The BiFE revealed good linear response in the examined concentration range of 1 to 45 nmolL(-1) testosterone in Britton-Robinson buffer, pH 5.0 containing 3 mmolL(-1) cetyltrimethylammonium bromide. The limit of detection was 0.3 nmolL(-1) (0.09 ng mL(-1)). Finally, the BiFE was satisfactorily applied for quantitation of testosterone in both pharmaceutical (oil-based ampoule) and biological (human urine) samples.