PubMed İndeksli Yayınlar Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.14720/6

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The Performance of Cathodically Pretreated Boron-Doped Diamond Electrode in Cationic Surfactant Media for Enhancing the Adsorptive Stripping Voltammetric Determination of Catechol-Containing Flavonoid Quercetin in Apple Juice
(Elsevier Science Bv, 2018) Abdullah, Abdullah A.; Yardim, Yavuz; Senturk, Zuhre
In the present paper, an electroanalytical methodology was developed for the determination of an important catechol-containing flavonoid derivative, quercetin using adsorptive stripping voltammetry at a cathodically pretreated boron-doped diamond electrode. In cyclic voltammetry, the compound showed a couple of oxidation/reduction peak at low positive potentials, and additional two oxidation peaks at more positive potentials. The sensitivity of the stripping voltammetric measurements was significantly improved when the cationic surfactant, cetyltrimethylammonium bromide (CTAB) was present in the electrolyte solution. Using square-wave stripping mode, a highly linear analytical curve was obtained for quercetin determination in 0.1 M acetate buffer solution (pH 4.7) containing 3 x 10(-4) M CTAB at + 0.37 V (vs. Ag/AgCl) (after 30 s accumulation at open-circuit condition) in the range of 0.5-200 ng mL(-1) (1.7 x 10(-9)-3.3 x 10(-7) M), with a detection limit of 0.132 ng mL(-1) (4.4 x 10(-10) M). As an example, the practical applicability of proposed method was successfully tested with the measurement of quercetin concentration in commercial apple juice samples.
Simultaneous Voltammetric Determination of Vanillin and Caffeine in Food Products Using an Anodically Pretreated Boron-Doped Diamond Electrode: Its Comparison With Hplc-Dad
(Elsevier Science Bv, 2017) Ali, Hoshyar Saadi; Abdullah, Abdullah A.; Pinar, Pinar Talay; Yardim, Yavuz; Senturk, Zuhre
This paper describes an electroanalytical method for the simultaneous determination of vanillin (VAN) and caffeine (CAF) using an anodically pretreated boron-doped diamond electrode. Selective determination of one compound in the presence of other one was also realized. Both compounds yielded a single irreversible oxidation peak using cyclic voltammetry. The nature of the electrode reaction was found to be diffusion controlled with contribution of adsorption. By using square-wave adsorptive stripping voltammetry after 60 s accumulation under open-circuit voltage, method allowed simultaneous determination of VAN and CAF in phosphate buffer, pH 2.5, with detection limits of 0.234 g (1.54x10(-6) M) and 0.071 mu g mL(-1) (3.66x10(-7)M), respectively. The proposed method was successfully applied in the selective and simultaneous determination of VAN and CAF in commercial food and beverage samples. In addition, for the comparison, high-performance liquid chromatographic method with diode-array detection was developed for the first time for their simultaneous determination.

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Browsing PubMed İndeksli Yayınlar Koleksiyonu by Author "Abdullah, Abdullah A."