scholarly journals Construction of a simple and selective electrochemical sensor based on Nafion/TiO2 for the voltammetric determination of olopatadine

Author(s):  
Mohammad Mehmandoust ◽  
Amirhossein Mehmandoust ◽  
Nevin Erk

A selective and facile voltammetric method based on titanium dioxide nanoparticles and Nafion (Nafion/TiO2 NPs) on the screen-printed electrode (SPE) was proposed for olopatadine determination. Followed by the synthesis of TiO2 nanoparticles, various methods, including high-resolution transmission electron microscopy (HR-TEM), ultraviolet-visible spectroscopy (UV-Vis), energy-dispersive X-ray (EDX) Raman spectrum, and electrochemical impedance spectroscopy (EIS) were utilized to characterize the nanomaterials. Nafion/TiO2 on the screen-printed electrode (NFN/TiO2/SPE) was used to determine olopatadine in concentration ranges of 0.01 to 0.07 and 0.07 to 14.6 µM with a limit of quantification as low as 7.0 nM, via differential pulse voltammetry technique. The NFN/TiO2/SPE offered a high-performance ability to determine olopatadine in the eye drop sample with satisfactory recovery data of 98.2–99.0 %. Also, the developed electrode showed good reproducibility, repeatability, and high selectivity features. The obtained results indicate that NFN/TiO2/SPE could be utilized as an appropriate candidate for electrochemical olopatadine sensing.

2019 ◽  
Vol 97 (2) ◽  
pp. 140-146
Author(s):  
Tian Gan ◽  
Zhikai Wang ◽  
Mengru Chen ◽  
Wanqiu Fu ◽  
Haibo Wang ◽  
...  

In this work, the Ag@Cu particles with yolk–shell nanostructure was prepared by facile solvothermal method, which was modified on glassy carbon electrode (GCE) to fabricate electrochemical sensor for the convenient and fast determination of p-aminobenzoic acid (PABA). The surface morphology and electrochemical properties of the as-prepared Ag@Cu nanocomposite modified electrode were characterized by scanning electron microscopy, transmission electron microscopy, chronocoulometry, and electrochemical impedance spectroscopy. Further, the electrochemical sensing of PABA was performed on the Ag@Cu/GCE using cyclic voltammetry and differential pulse voltammetry techniques, showing high catalytic activity. Under the optimal conditions, the sensor exhibited a wide linear range, high sensitivity, and low detection limit of 0.315 μmol/L for PABA. The developed sensor was also successfully applied for PABA detection in anesthetic and cosmetics with satisfactory results.


Author(s):  
Kuddusi Karaboduk

Abstract Objectives The aim of this study is to investigate the electrochemical behavior of Sudan II (SuII) using a screen printed gold electrode (SPGE) modified with 1,4-dithiothreitol (DTT) and to determine the amount of Sudan II by voltammetry. Materials and Methods A DTT modified screen printed gold electrode (DTT/SPGE) was fabricated and its application for differential pulse voltammetric (DPV) determination of SuII was reported. Fourier transform infrared spectroscopy (FT-IR), cyclic voltammetry (CV) and electrochemical impedance spectroscopy were used for the characterization of modified electrode. The effects of instrumental and chemical parameters were optimized for the determination of SuII. The fabricated electrode was used for the analysis of SuII in fortified and real samples. High performance liquid chromatography (HPLC) was preferred as a reference method for the evaluation of the obtained voltammetric results. Results The electrochemical studies and FT-IR demonstrated that the SPGE was modified with DTT. The obtained peak current at DTT/SPGE was 6.67 times higher than that recorded with SPGE. At the optimized conditions of DPV in pH = 2.5 of H2SO4, the oxidation peak current of SuII was proportional to its concentration in range: 0.001 - 1.500 μmol L -1 with a detection limit of 0.0002 μmol L -1 (S/N=3). For the analysis of SuII, 101.67 - 104.33% of recovery percentage was obtained. Conclusions A new electrode was successfully improved for the determination of SuII. This highly selective and sensitive electrode supplied the fast determination of SuII in ketchup, chili sauce and salsa dip sauce. In addition, voltammetric and chromatographic results are found to be consistent.


2019 ◽  
Vol 9 (2) ◽  
pp. 113-123 ◽  
Author(s):  
Sayed Zia Mohammadi ◽  
Hadi Beitollahi ◽  
Tahereh Rohani ◽  
Hossein Allahabadi

Electrochemical characteristics of carvacrol were investigated on a screen-printed electrode (SPE) modified with La2O3/Co3O4 nanocomposite by using voltammetric techniques, which displayed a well-defined peak for sensitive carvacrol determination in phosphate buffer solution (PBS) at pH 7.0. La2O3/Co3O4 nanoparticles demonstrated suitable catalytic activity for carvacrol determination by differential pulse voltammetry (DPV) technique. Besides, determination of carvacrol in a real samples was recognized in the light of electrochemical findings and a validated voltammetric technique for quantitative analysis of carvacrol in a real formulation was proposed. The DPV peak currents were found to be linear in the concentration range of 10.0 to 800.0 μM. The limit of detection (LOD) was found to be 1.0 μM.


2019 ◽  
Vol 9 (3) ◽  
pp. 187-195 ◽  
Author(s):  
Somayeh Tajik ◽  
Hadi Beitollahi ◽  
Mohammad Reza Aflatoonian

Flower-like La3+/ZnO nanocomposite was facile synthesized. A simple and ultrasensitive sensor based on graphite screen printed electrode (SPE) modified by La3+/ZnO nanoflower was developed for the electrochemical determination of dopamine. The electrochemical behavior of dopamine was studied in 0.1 M phosphate buffer solution (PBS) using cyclic voltammetry (CV), chronoamperometry (CA) and differential pulse voltammetry (DPV). Compared with the unmodified graphite screen printed electrode, the modified electrode facilitates the electron transfer of dopamine, since it notably increases the oxidation peak current of dopamine. Also, according to CV results the maximum oxidation of dopamine on La3+/ZnO/SPE occurs at 150 mV which is about 140 mV more negative compared with unmodified SPE. Under optimized conditions, the modified electrode exhibited a linear response over the concentration range from 0.15 to 300.0 μM, with a detection limit of 0.08 μM (S/N = 3). The proposed sensor exhibited a high sensitivity, good stability and was successfully applied for dopamine determination in dopamine ampoule, with high recovery.


2020 ◽  
Vol 16 ◽  
Author(s):  
Vesna Antunović ◽  
Rada Baošić ◽  
Aleksandar Lolić

Background: Diazepam belongs to the group of 1,4-benzodiapines. It is used for the treatment of anxiety, convulsions and as a muscle relaxant. The presence of 4,5-azomethine group enables its electrochemical detection Introduction: A screen-printed electrode modified with antimony film was used for the determination of diazepam in pharmaceutical preparations Methods: Electrode modification was done by ex-situ deposition of antimony on commercially available screen-printed electrode. Parameters affecting the electroanalytical response of the sensor, such as deposition potential, deposition time, and antimony concentration, were examined and optimized. The modified electrode showed enhanced electroactivity for diazepam reduction compared to unmodified electrode. Under optimal conditions, linear sweep voltammetry was used for the determination of analyte Results: The sensor showed linear dependence in the range from 0.5 to 10 μmol/L, the correlation coefficient was 0.9992. The limit of detection was 0.33 μmol/L, corresponding limit of quantification was 1.08 μmol/L. Modification enabled determination of diazepam in the presence of oxygen. Conclusion: The modified electrode was used for the determination of diazepam in tablets. Results confirmed the applicability of the electrochemical sensor


Biosensors ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 23 ◽  
Author(s):  
Sanaz Akbarzadeh ◽  
Habibollah Khajesharifi ◽  
Michael Thompson

In this paper, an electrochemical technique is introduced for the determination of streptomycin (STR) in the presence of oxytetracycline (OTC) in milk samples. A novel bifunctional modified screen-printed electrode (SPE) modified with oracet blue, silver nanoparticles, and graphene oxide (OB/SNPs/GO/SPE) was fabricated. The modified electrode plays a catalyzer role for electrooxidation of STR at pH = 7.0 and reveals a facile a separation between the oxidation peaks of STR and OTC. Calculation of kinetic parameters such as the electron transfer coefficient α and the heterogeneous rate constant k´ of STR at the OB/SNPs/GO/SPE as 8.1 ± 0.07 cm s−1 and 0.32 have been obtained based on the theoretical model of Andrieux and Saveant. A differential pulse voltammetric measurement demonstrates two linear dynamic ranges, 0.4 to 240.0 nM and 240.0 to 720.0 nM and a detection limit of 0.17 nM for STR. The sensitivities of the OB/SNPs/GO/SPE towards the oxidation of STR in the absence and presence of OTC were 2.625 × 10−1 and 2.633 × 10−1 µA/µM, respectively.


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