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Öğe Electrochemical performance of boron-doped diamond electrode in surfactant-containing media for ambroxol determination(Elsevier, 2014-07-17) Levent, Abdulkadir; Yardım, Yavuz; Şentürk, ZühreA novel application of boron-doped diamond electrode is introduced for the determination of ambroxol, a potential antioxidant drug belonging to the expectorant class. The electrochemical oxidation of ambroxol was first investigated by cyclic voltammetry using boron-doped diamond and glassy carbon electrodes in aqueous solutions both with and without the addition of surfactant. The compound was irreversibly oxidized in one/two steps at high positive potentials, resulting in the formation of a couple with a reduction and re-oxidation wave at less positive potentials. Special attention was given to the use of adsorptive stripping voltammetry at a surface of mildly oxidized boron-doped diamond electrode in aqueous solutions over the pH range of 1.0–10.0. Addition of anionic surfactant (sodium dodecylsulfate) to ambroxol-containing electrolyte enhanced the stripping current signal. Using square-wave stripping mode, the drug yielded a well-defined voltammetric response in phosphate buffer pH 2.5 containing 4 × 10−4 M sodium dodecylsulfate at +1.02 V (versus Ag/AgCl) (after 30 s accumulation at +0.50 V). The process could be used to determine ambroxol in the concentration range of 0.05–0.7 μM, with a detection limit of 0.010 μM (4.2 ng mL−1). The suggested method was successfully applied to pharmaceuticals and spiked human urine samples.Öğe Graphene/Nafion composite film modified glassy carbon electrode for simultaneous determination of paracetamol, aspirin and caffeine in pharmaceutical formulations(ScienceDirect, 2016-05-16) Yiğit, Aydın; Yardım, Yavuz; Çelebi, Metin; Levent, Abdulkadir; Şentürk, ZühreA graphene-Nafion compositefilm was fabricated on the glassy carbon electrode (GR-NF/GCE), and usedfor simultaneous determination of paracetamol (PAR), aspirin (ASA) and caffeine (CAF). The electro-chemical behaviors of PAR, ASA and CAF were investigated by cyclic voltammetry and square-waveadsorptive anodic stripping voltammetry. By using stripping one for simultaneous determination of PAR,ASA and CAF, their electrochemical oxidation peaks appeared atþ0.64, 1.04 and 1.44 V, and good linearcurrent responses were obtained with the detection limits of 18 ng mL 1(1.2 10 9M), 11.7 ng mL 1(6.5 10 8M) and 7.3 ng mL 1(3.8 10 8M), respectively. Finally, the proposed electrochemical sensorwas successfully applied for quantifying PAR, ASA and CAF in commercial tablet formulations.
