Browsing by Author "Şentürk, Z."

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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.
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.