Browsing by Author "Uslu, Bengi"

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Citation Count: 45
Electrochemical behavior of tadalafil on TiO₂ nanoparticles-MWCNT composite paste electrode and its determination in pharmaceutical dosage forms and human serum samples using adsorptive stripping square wave voltammetry
(Springer, 2014) Demir, Ersin; Inam, Recai; Ozkan, Sibel A.; Uslu, Bengi
A sensitive and selective electroanalytical method for the determination of tadalafil (TAD) using adsorptive stripping square wave voltammetry at multiwalled carbon nanotube paste electrode (MWCNTPE) and modified TiO2-multiwalled carbon nanotube paste electrode (TiO2-MWCNTPE) was presented. The calibration curves were linear in the concentration range of 3.6-8.1 and 12.7-61.1 mu M on MWCNTPE, 0.27-15.2 mu M on TiO2-MWCNTPE. The recommended method was successfully applied to the determination of the drug in tablets and human serum samples with good recoveries. The selectivity of the proposed method was considered in the presence of Ca2+, K+, Na+, 2-mercapto benzimidazole, thiourea, and dopamine by means of recovery tests. Interfering agents did not show considerable effect on TAD determination. No electroactive interferences from the tablet excipients and endogenous substances from biological material were detected. The possible electrooxidation pathway and the number of transferred electrons were also investigated.
Citation Count: 6
VOLTAMMETRIC DETERMINATION OF VARDENAFIL ON MODIFIED ELECTRODES CONSTRUCTED BY GRAPHITE, METAL OXIDES AND FUNCTIONALIZED MULTI-WALLED CARBON NANOTUBES
(Editura Acad Romane, 2019) Demir, Ersin; Bozal-Palabiyik, Burcin; Uslu, Bengi; Inam, Recai
The voltammetric behavior of the vardenafil was investigated by means of square wave stripping voltammetry (SWSV), differential pulse stripping voltammetry (DPSV) and cyclic voltammetry (CV) on the modified electrodes constructed by graphite, metal oxide and functionalized multi-walled carbon nanotubes (MWCNT).Different experimental conditions were optimized such as pH and electrolyte type, accumulation potential and accumulation time for both techniques and step potential, pulse amplitude and frequency for SWSV. In the optimum conditions a linear relationship has been constructed in the concentration range of 0.02 to 1.0 mg/L and 0.01 to 0.5 mg/L for SWSV and DPSV in pH 3.0 phosphate buffer solution, respectively. Limit of detection (LOD) values for vardenafil determinations were13.6 mu g/L and 4.38 mu g/L for SWSV and DPSV, respectively. Quantifications were performed on commercial pharmaceutical tablets and synthetic blood serum using both techniques. The relative errors were +5.0% and -3.0% for SWSV and DPSV, respectively in the determination of vardenafil active ingredient in Levitra (R) tablet. SWS and DPS voltammetric determination of synthetic blood serum spiked with 50.0 mu g/L vardenafil exhibited 100.8% and 104.4% recovery, respectively. Interference effects of some organic species such as ascorbic acid, uric acid, dopamine, glucose have also been investigated.