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Öğe Voltammetric behavior of testosterone on bismuth film electrode: Highly sensitive determination in pharmaceuticals and human urine by square‐wave adsorptive stripping voltammetry(Wiley Online Library, 2015-03-20) Levent, Abdulkadir; Altun, Ahmet; Taş, Süleyman; Yardım, Yavuz; Şentürk, ZühreIn 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 nmol L−1 testosterone in BrittonRobinson buffer, pH 5.0 containing 3 mmol L−1 cetyltrimethylammonium bromide. The limit of detection was 0.3 nmol L−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.Öğe Sensitive voltammetric determination of testosterone in pharmaceuticals and human urine using a glassy carbon electrode in the presence of cationic surfactant(Elsevier, 2014-05-10) Levent, Abdulkadir; Altun, Ahmet; Yardım, Yavuz; Şentürk, ZühreIn 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.
