Metal-free graphene-based nanoelectrodes for the electrochemical determination of ascorbic acid (AA) and p-nitrophenol (p-NP): implication towards biosensing and environmental monitoring

2021 ◽  
Vol 45 (10) ◽  
pp. 4666-4674
Author(s):  
Vijay S. Sapner ◽  
Bhaskar R. Sathe
Keyword(s):  
Ascorbic Acid ◽  
Phosphate Buffer Solution ◽  
Electrochemical Determination ◽  
Buffer Solution ◽  
Functionalized Graphene Oxide ◽  
Free Graphene ◽  
Potential Stability ◽  
Current Potential

Herein, tyramine functionalized graphene oxide electrocatalyst is used for the electrochemical determination of ascorbic acid and p-nitrophenol in 1 M phosphate buffer solution at pH-7  with long term current/potential stability and reproducibility.

Electrochemical Determination of Norepinephrine at Poly (p-aminobenzenesulfonic Acid) Modified Sensor

2020 ◽  
Vol 16 (5) ◽  
pp. 591-600
Author(s):  
Şevket Zişan Yağcı ◽  
Ebru Kuyumcu Savan ◽  
Gamze Erdoğdu
Keyword(s):  
Ascorbic Acid ◽  
Limit Of Detection ◽  
Phosphate Buffer Solution ◽  
Differential Pulse ◽  
Electrochemical Determination ◽  
Buffer Solution ◽  
Oxidation Current ◽  
Pulse Voltammetry ◽  
Modified Sensor

Objective: In this study, it was aimed to prepare an electrochemical sensor capable of assigning Norepinephrine in the presence of an interference such as ascorbic acid. Methods: A sensitive modified sensor was prepared by electrodeposition of p-aminobenzenesulfonic acid (p-ABSA) to the glassy carbon electrode by cyclic voltammetry. The electrooxidation of Norepinephrine was accomplished by cyclic and differential pulse voltammetry. Results: The current values were enhanced and the peak potentials of Norepinephrine and ascorbic acid were separated at the sensor compared to the bare electrode. There was linearity between the oxidation current and concentration of Norepinephrine ranging from 0.5 to 99.8 μM in phosphate buffer solution at pH 7.0. The limit of detection was 10.0 nM and the sensitivity was 0.455 μA/μM. Conclusion: The determination of Norepinephrine was successfully performed in real samples such as blood serum and urine at the poly (p-ABSA) sensor. To the best of our knowledge, this is the first study to detect Norepinephrine in the presence of ascorbic acid at poly (p-ABSA) modified sensor in the literature.

Sensitive Determination of Epinephrine in the Presence of Ascorbic Acid at Poly(diphenylamine sulfonic acid) Modified Sensor

2020 ◽  
Vol 18 (4) ◽  
pp. 253-258
Author(s):  
Gamze Erdoğdu
Keyword(s):  
Ascorbic Acid ◽  
Sulfonic Acid ◽  
Limit Of Detection ◽  
Phosphate Buffer Solution ◽  
Differential Pulse ◽  
Buffer Solution ◽  
Sensitive Determination ◽  
Pulse Voltammetry ◽  
Modified Sensor

A sensitive and simple modified sensor was prepared by electrodeposition of diphenylamine sulfonic acid (DPSA) to the glassy carbon electrode surface by cyclic voltammetry (CV) technique. The electrooxidation of epinephrine (EP) was accomplished by CV and differential pulse voltammetry at poly(DPSA) modified sensor. As a result of the findings, the current values were enhanced and both substances were separated at the modified sensor compared to the bare electrode. There was linearly between the oxidation current and concentration of EP from 0.2 to 100 μM in phosphate buffer solution at pH 7.0. The limit of detection was 5.0 nM and the sensitivity was 0.4205 μA/μM. The determination of EP was successfully and satisfactorily carried out in real samples such as human blood serum and urine at the poly(DPSA) sensor. To the best knowledge of this work, this is the first study that detect the EP in the presence of ascorbic acid at poly(DPSA) sensor in the literature.

scholarly journals A novel dopamine electrochemical sensor based on La3+/ZnO nanoflower modified graphite screen printed electrode

2019 ◽  
Vol 9 (3) ◽  
pp. 187-195 ◽  
Author(s):  
Somayeh Tajik ◽  
Hadi Beitollahi ◽  
Mohammad Reza Aflatoonian
Keyword(s):  
Modified Electrode ◽  
Phosphate Buffer Solution ◽  
High Sensitivity ◽  
Differential Pulse ◽  
Electrochemical Determination ◽  
Screen Printed Electrode ◽  
Buffer Solution ◽  
Optimized Conditions ◽  
Screen Printed

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.

Synthesis and characterisation of a novel bi-nuclear copper2+ complex and its application as electrode-modifying agent for simultaneous voltammetric determination of dopamine and ascorbic acid

2014 ◽  
Vol 68 (2) ◽  
Author(s):  
Diganta Das ◽  
Babita Sarma ◽  
Sangita Haloi
Keyword(s):  
Ascorbic Acid ◽  
Modified Electrode ◽  
Phosphate Buffer Solution ◽  
Oxidation Potential ◽  
Buffer Solution ◽  
Electrode Potentials ◽  
Electro Oxidation ◽  
Simultaneous Voltammetric Determination ◽  
Complex Ion

AbstractA new binuclear complex of copper2+, [LCu2+(CH3COO)2Cu2+L](CH3COO)2 where L is N,N-bis(phthalimide)ethylenediamine, was synthesised and characterised. The complex ion [LCu2+ (CH3COO)2Cu2+L]2+ was encapsulated into ZSM-5 zeolite and used to modify the surface of the glassy carbon electrode. This modified electrode, in a phosphate buffer solution at pH 7.0, exhibited an oxidation potential for dopamine (DA) and ascorbic acid (AA) at electrode potentials of 0.230 V and −0.090 V vs. Ag/AgCl respectively, a separation of 0.320 V. The electro-oxidation of DA or AA on the modified electrode is independent of each other. No interference was observed from Na+, K+, Cl−, SO42−, Mg2+, Ca2+, Zn2+, Fe2+, and glucose. The detection limits obtained were 2.91 × 10−7 M for DA and 3.5 × 10−7 M for AA.

scholarly journals Electrochemical detection of carbidopa using a ferrocene-modified carbon nanotube paste electrode

2009 ◽  
Vol 74 (12) ◽  
pp. 1443-1453 ◽  
Author(s):  
Halimeh Yaghoubian ◽  
Hassan Karimi-Maleh ◽  
Ali Khalilzadeh ◽  
Fatemeh Karimi
Keyword(s):  
Phosphate Buffer Solution ◽  
Modified Carbon Paste Electrode ◽  
Carbon Paste ◽  
Buffer Solution ◽  
Long Term Stability ◽  
Good Surface ◽  
Carbon Nanotube Paste Electrode ◽  
Paste Electrode

A chemically modified carbon paste electrode (MCPE) containing ferrocene (FC) and carbon nanotubes (CNT) was constructed. The electrochemical behavior and stability of the MCPE were investigated by cyclic voltammetry. The electrocatalytic activity of the MCPE was investigated and it showed good characteristics for the oxidation of carbidopa (CD) in phosphate buffer solution (PBS). A linear concentration range of 5 to 600 ?M CD, with a detection limit of 3.6?0.17 ?M CD, was obtained. The diffusion coefficient of CD and the transfer coefficient (?) were also determined. The MCPE showed good reproducibility, remarkable long-term stability and especially good surface renewability by simple mechanical polishing. The results showed that this electrode could be used as an electrochemical sensor for the determination of CD in real samples, such as urine samples.

Non-enzymatic determination of purine nucleotides using a carbon dot modified glassy carbon electrode

2019 ◽  
Vol 11 (30) ◽  
pp. 3866-3873 ◽  
Author(s):  
R. Karthikeyan ◽  
D. James Nelson ◽  
S. Abraham John
Keyword(s):  
Glassy Carbon ◽  
Low Cost ◽  
Phosphate Buffer Solution ◽  
Purine Nucleotides ◽  
Buffer Solution ◽  
Solution Ph ◽  
Carbon Dot ◽  
Enzymatic Determination ◽  
Sensitive Determination

Selective and sensitive determination of one of the purine nucleotides, inosine (INO) using a low cost carbon dot (CD) modified glassy carbon (GC) electrode in 0.2 M phosphate buffer solution (pH 7.2) was demonstrated in this paper.

Electrochemical Determination of Uric Acid at CdTe Quantum Dot Modified Glassy Carbon Electrodes

2015 ◽  
Vol 98 (5) ◽  
pp. 1260-1266 ◽  
Author(s):  
Deng Pan ◽  
Shengzhong Rong ◽  
Guangteng Zhang ◽  
Yannan Zhang ◽  
Qiang Zhou ◽  
...  
Keyword(s):  
Uric Acid ◽  
Quantum Dot ◽  
Glassy Carbon ◽  
Semiconductor Nanocrystals ◽  
Phosphate Buffer Solution ◽  
Differential Pulse ◽  
Electrochemical Determination ◽  
Buffer Solution ◽  
Peak Current ◽  
Cdte Quantum Dot

Abstract Cyclic voltammetry and differential pulse voltammetry were used to investigate the electrochemical behavior of uric acid (UA) at a CdTe quantum dot (QD) modified the glassy carbon electrode (GCE). CdTe QDs, as new semiconductor nanocrystals, can greatly improve the peak current of UA. The anodic peak current of UA was linear with its concentration between 1.0 × 10–6 and 4.0 × 10–4 M in 0.1 M pH 5.0 phosphate buffer solution. The LOD for UA at the CdTe electrode (1.0 × 10–7 M) was superior to that of the GCE. In addition, we also determined the effects of scan rate, pH, and interferences of UA for the voltammetric behavior and detection. The results indicated that modified electrode possessed excellent reproducibility and stability. Finally, a new and efficient electrochemical sensor for detecting UA was developed.

Development and Validation of HPLC Determination of related Substances in A Novel Anticonvulsant agent Epimidin

2021 ◽  
pp. 3223-3231
Author(s):  
Hanna I. Severina ◽  
Svitlana M. Gubar ◽  
Ivan V. Bezruk ◽  
Anna S. Materiienko ◽  
Liudas Ivanauskas ◽  
...  
Keyword(s):  
Mobile Phase ◽  
Phosphate Buffer Solution ◽  
Anticonvulsant Drug ◽  
Strong Acid ◽  
Gradient Elution ◽  
Stress Conditions ◽  
Drug Candidate ◽  
Buffer Solution ◽  
Related Substances

1-(4-methoxyphenyl)-5-[2-[4-(4-methoxyphenyl)piperazin-1-yl]-2-oxo-ethyl]pyrazolo[3,4-d]pyrimidin-4-one has been reported as a promising new anticonvulsant drug candidate with a code name “Epimidin”. A new HPLC method for the related substances determination of potential active pharmaceutical ingredient has been developed and validated. The method uses ACE C18 column (250x4.6mm, 5µm) and gradient elution. Mobile phase consisted of a mixture of methanol R (mobile phase A) and phosphate buffer solution with triethanolamine, adjusted to pH 7.0 (mobile phase B). During the analysis, the ratio of mobile phases was changing according to a gradient mode at a flow rate of 1ml/min. The DAD detection was set at 240nm. The method was validated according to the ICH guidelines and requirements of State Pharmacopoeia of Ukraine. Drug substance was thoroughly explored for stability assessments under various stress conditions such as high temperature, as well as the influence of strong acid and base and oxidizing agents. The obtained solutions were analyzed by HPLC and LC/MS. It has been shown that the substance Epimidin was not resistant to the action of peroxide, alkali and acid decomposition – the mentioned stress conditions lead to the formation of unidentified impurities.

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