Browsing by Author "Şentürk, Z."

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Electroanalytical Determination of Salbutamol in Pharmaceutical Formulations Using Cathodically Pretreated Boron-Doped Diamond Electrode
(Marmara University, 2018) Talay Pınar, P.; Ali, H.S.; Abdullah, A.A.; Yardim, Y.; Şentürk, Z.
This paper examined for the first time the possibilities of the usage of the cathodically pretreated boron-doped diamond (CPT-BDD) electrode for the redox behavior of salbutamol (SAL) using cyclic and adsorptive stripping voltammetry. The cyclic voltammograms showed an irreversible and adsorption-controlled oxidation peak at about +1.0 V in the Britton-Robinson (BR) buffer (pH 9.0) solution. Under the optimized experimental condition, using square-wave adsorptive stripping mode, the compound yielded a well-defined voltammetric response in BR buffer, pH 9.0 at +0.95 V (vs. Ag/AgCl) (after 30 s accumulation at an open circuit condition). A linear calibration graph was obtained in the concentration range of 4.15 to 83 μg mL-1 (1.73x10-5-3.47x10-4 M). A detection limit of 1.21 μg mL-1 (5.06x10-6 M) was observed. The suggested method was also applied to the determination of SAL in the drug formulations. © 2018 Elsevier B.V., All rights reserved.
Electrochemical Behavior of Folic Acid at a Boron-Doped Diamond Electrode: Its Adsorptive Stripping Voltammetric Determination in Tablets
(Turkish Pharmacists Association, 2014) Yardim, Y.; Şentürk, Z.
The electrochemical properties of folic acid were investigated in pH range 1.0-9.0 by cyclic, linear sweep and adsorptive stripping voltammetry. The compound was irreversibly oxidized at an anodically pretreated boron-doped diamond electrode in one or two oxidation steps, which are concentration- and/or pH-dependent. Using square-wave stripping mode, folic acid yielded well-defined voltammetric responses in both 0.1M perchloric acid and 0.1M Britton-Robinson buffer, pH 6.0 with limits of detection 0.035 μg/mL (7.93 10-8 M) and 0.14 μg/mL (3,2 × l0-7 M), respectively, after an accumulation of 120 s at open-circuit condition. Practical applicability of the newly developed approach was verified by the direct assays of tablet dosage forms.
Electrochemical Determination of Norepinephrine by Adsorptive Stripping Voltammetry Using a Bare Boron-Doped Diamond Electrode
(Editura Academiei Romane, 2019) Keskin, E.; Yardim, Y.; Levent, A.; Şentürk, Z.
A boron-doped diamond electrode was used for the first time for sensitive and selective analysis of norepinephrine (NE) using square wave voltammetry (SWV) technique. NE displayed one well-defined, irreversible and adsorption-controlled oxidation peak at about +0.85 V (vs. Ag/AgCl) in Britton-Robinson buffer (BR, 0.1 M, pH 2.0) using cyclic voltammetry (CV) technique. The effect of supporting electrolyte, solution pH and instrumental variables on oxidation peak current were optimized. In optimal experiment conditions, it was found that there was an excellent correlation between oxidation peak current and NE concentration in the range of 1 to 100 μg mL-1 (4.9×10-6 M-4.9×10-4 M) with a detection limit of 0.254 μg mL-1 (1.2×10-6 M) in 0.1 M BR buffer (pH 2.0) solution employing square-wave stripping mode. The developed technique can be used for the quantification of NE in the pharmaceutical formulation with acceptable recoveries. © 2020 Elsevier B.V., All rights reserved.
Trace Determination of Dna in an Amaryllidaceae Plant, Narcissus Tazetta by Square-Wave Stripping Voltammetry Based on Guanine Signal
(2007) Yardim, Y.; Şentürk, Z.; Özsöz, M.; Özdemir, K.; Atalan, E.
This study is, to our knowledge, the first application of electrochemical DNA biosensor for the quantification of DNA in plant extracts. The DNA biosensor was assembled by immobilizing the double-stranded fish sperm DNA on the surface of a singleuse pencil graphite electrode. Square-wave voltammetric method with the baseline correction was carried out to evaluate the oxidation signal of the guanine base. The experimental variables such as solution pH, buffer concentration, immobilization time, stirring speed, and square-wave parameters were optimized. The extremely low detection limit (0.36 ng/mL) was coupled to a good surface-to-surface reproducibility (a relative standard deviation of 8.4% for 7 repetitive measurements of 40 ng/mL). The renewable and low-cost DNA biosensor developed in this study using pencil graphite electrode was applied to the determination of DNA isolated from an Amaryllidaceae plant, Narcissus tazetta.