Selective Voltammetric Detection of Dopamine in the Presence of Ascorbic Acid at Poly(p-methoxyphenol)-Modified Electrode

2020 ◽  
Vol 18 (3) ◽  
pp. 222-226
Author(s):  
Gamze Erdoğdu
Keyword(s):  
Ascorbic Acid ◽  
Detection Limit ◽  
Modified Electrode ◽  
Oxidative Polymerization ◽  
Phosphate Buffer Solution ◽  
Relative Sensitivity ◽  
High Concentration ◽  
Buffer Solution ◽  
Solution Ph ◽  
Voltammetric Detection

A gold electrode was modified with electropolymerized films of p-methoxyphenol by its oxidative polymerization from an alkaline solution by cyclic voltammetry. The modified electrode was then used to determine dopamine (DA) in the presence of a high concentration of ascorbic acid (AA) by differential pulse voltammetry. The peak positions as well as relative sensitivity DA/AA were affected by the potential window used for the polymerization. For polymerization between 0 and 1.0 V, the peak potentials recorded in a phosphate buffer solution (pH = 7.2) were 516 and 312 mV versus Ag/AgCl for DA and AA, respectively. In addition to the effects of pH and the type of electrolyte on the linearity range and detection limit are investigated. The detection limit for 3s-test is 0.1 nM. The high selectivity and sensitivity for DA was found to be due to charge discrimination/analyte accumulation.

scholarly journals Electrochemical Polymerised Graphene Paste Electrode and Application to Catechol Sensing

2019 ◽  
Vol 13 (1) ◽  
pp. 81-87 ◽  
Author(s):  
Jamballi G. Manjunatha
Keyword(s):  
Modified Electrode ◽  
Limit Of Detection ◽  
Phosphate Buffer Solution ◽  
Sample Pretreatment ◽  
Differential Pulse ◽  
Buffer Solution ◽  
Solution Ph ◽  
Graphene Paste Electrode ◽  
Paste Electrode

Objective: To build up an advantageous strategy for sensitive determination of catechol (CC), a poly (proline) modified graphene paste electrode (PPMGPE) was fabricated and used as a voltammetric sensor for the determination of CC. Methods: The performance of the modified electrode was studied using cyclic voltammetric (CV) and differential pulse voltammetric method (DPV). The modified electrode was characterized by CV and DPV. The surface of the modified electrode was examined by FESEM. The electrochemical behavior of CC in phosphate buffer solution (pH 7.5) was inspected using bare graphene paste electrode (BGPE) and PPMGPE. Results & Conclusion: The PPMGPE shows a lower limit of detection, calculated to be 8.7×10–7mol L−1 (S/N=3). This modified electrode was applied successfully for the determination of CC in water samples without applying any sample pretreatment.

scholarly journals Voltammetric Detection of Dopamine in Presence of Ascorbic Acid and Uric Acid at Poly (Xylenol Orange) Film-Coated Graphite Pencil Electrode

2011 ◽  
Vol 2011 ◽  
pp. 1-8 ◽  
Author(s):  
Umesh Chandra ◽  
B. E. Kumara Swamy ◽  
Ongera Gilbert ◽  
B. S. Sherigara
Keyword(s):  
Ascorbic Acid ◽  
Uric Acid ◽  
Limit Of Detection ◽  
Xylenol Orange ◽  
Excellent Result ◽  
Phosphate Buffer Solution ◽  
Differential Pulse ◽  
Buffer Solution ◽  
Voltammetric Detection ◽  
Simultaneous Study

Poly (xylenol orange) film-coated graphite pencil electrode was fabricated for the detection of dopamine in the presence of ascorbic acid and uric acid in phosphate buffer solution of pH 7. The redox peaks obtained at modified electrode shows a good enhancement. The scan rate effect was found to be a diffusion-controlled electrode process. The electrochemical oxidation of dopamine was depended on pH, and the limit of detection was found to be 9.1×10−8 M. The simultaneous study gave and excellent result with great potential difference between dopamine and other bioactive organic molecules by using both cyclic voltammetric and differential pulse voltammetric techniques. The present modified graphite electrode was applied to the detection of dopamine in the injection samples, and the recovery obtained was satisfactory.

Sensitive Detection of Human Hemoglobin by MWCNTs-ionic Liquid: Anthraquinone Modified Electrode

2019 ◽  
Vol 9 (4) ◽  
pp. 479-485
Author(s):  
Aghdas Banaei ◽  
Mostafa Shourian ◽  
Fariba Dashtestani ◽  
Khadijeh Eskandari
Keyword(s):  
Ionic Liquid ◽  
Modified Electrode ◽  
Clinical Sample ◽  
Phosphate Buffer Solution ◽  
Cyclic Voltammograms ◽  
Buffer Solution ◽  
Solution Ph ◽  
Nano Composite ◽  
Composite Gels ◽  
Composite Gel

Introduction: Today, nano-composite gels based on multi-walled carbon nanotubes in room temperature ionic liquid (MWCNTs-IL-Gel) are an interesting subject. Materials and Methods: The nano-composite gels showed convenient electrochemical properties against redox activities of electroactive biomolecules. Also, the evaluation of hemoglobin concentration is a critical point in the clinical sample. So, the kind of nano-composite gel which is composed of NH2 functionalized MWCNTs and [amim] Br IL and anthraquinone 2-carboxilic acid (AQ) was fabricated and applied in electrochemical detection of hemoglobin. Cyclic voltammograms of NH2.MWCNTs-IL-AQ modified electrode exhibited redox peak sat -0.5 V (vs. Ag/AgCl) in 0.1 M phosphate buffer solution ((pH 7.0). Results: As the hemoglobin added into the measured solution, the redox current decreased. Conclusion: It can be concluded that the increment in the concentration of hemoglobin caused the decrease in the redox currents in cyclic voltammetry. The NH2.MWCNTs-IL-AQ would detect the concentration of hemoglobin from 1.64 x10−8 to 4.89x10−7 M.

scholarly journals Impact of Pasteurization on Ascorbic Acid in Orange Juice (Overview)

2020 ◽  
Vol 9 (3) ◽  
pp. 82
Author(s):  
Yuhui Ding
Keyword(s):  
Ascorbic Acid ◽  
Formic Acid ◽  
Orange Juice ◽  
Phosphate Buffer ◽  
Phosphate Buffer Solution ◽  
Standard Samples ◽  
Three Solutions ◽  
Buffer Solution ◽  
Solution Ph ◽  
Mobile Phases

Loss in Ascorbic Acid contents of orange juice heated under different situations and pH was researched. In this experiment, Navanila oranges from Spain were squeezed and filtered by using a vacuum pump to make orange juice samples. These samples were extracted and make up with 0.1% Formic Acid in HPLC water, HPLC water and phosphate buffer solution (pH=6). Pasteurization was achieved at 60, 65 and 70℃ over 15, 25 and 35min period by using the water bath method and cooled to room temperature immediately. After that, Ascorbic Acid contents were analyzed by HPLC and 0.1% Formic Acid in HPLC water, HPLC water and phosphate buffer solution (pH=6) were used as mobile phases separately for their solutions. HPLC standard samples of Ascorbic Acid were prepared which means 0.1g Ascorbic Acid was weighted and then diluted into 50-250mg/ L solutions to make calibration lines for three solutions. The wavelength of Ascorbic Acid was 245nm but it changed to 296nm when samples in phosphate buffer solution (pH=6). Results showed that Ascorbic Acid concentration is more at 60℃ at 15min and there was a total decline trend with the increase of time and temperature. After statistics analysis, it has a significant affect (P<0.5) related to Ascorbic Acid contents with temperature and pH.

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.

Detection of Hepatitis a Virus in Drinking Water by Enzyme -Immunoassay Using Ultracentrifugation for Virus Concentration

1985 ◽  
Vol 17 (10) ◽  
pp. 39-41 ◽  
Author(s):  
A. Schnattinger
Keyword(s):  
Membrane Filtration ◽  
Hepatitis A ◽  
Hepatitis A Virus ◽  
Solid Phase ◽  
Phosphate Buffer Solution ◽  
Enzyme Linked Immunosorbent Assay ◽  
Virus Concentration ◽  
Buffer Solution ◽  
Solution Ph ◽  
Two Stage

Ten litres of tapwater were seeded with 200 µl (8×108 HAV particles) of a commercial (Organon Teknika) suspension of hepatitis A virus. Following WALTER and RÜDIGER (1981), the contaminated tapwater was treated with a two-stage technique for concentration of viruses from solutions with low virus titers. The two-stage technique consists of aluminium hydroxideflocculation (200 mg/l Al2(SO4)3. 18 H2O, pH 5,4-5,6) as first stage, the second stage of a lysis of aluminium hydroxidegel with citric acid/sodium citrate-buffer (pH 4,7; 1 ml/l sample), separation of viruses from the lysate by ultracentrifugation and suspension in 1 ml phosphate buffer solution (pH 7,2). A commercial solid phase enzyme-linked immunosorbent assay (ELISA) was used for the detection of HAV. HAV was detecterl in the 10.000:1 concentrates, but not in the seeded 101 samples. Approximately 4×108 of the inoculated 8×108 HAV particles were found in the 1 ml concentrates. The efficiency of detection is about 50%, the virus concentration 5000-fold. Although the percentage loss of HAV in comparison with concentration by means of membrane filtration is similar, the ultracentrifugation method yields a larger sample/concentrate ratio, so that smaller amounts of HAV can be detected more efficiently because of the smaller end-volume.

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.

scholarly journals Electro-Polymerized Titan Yellow Modified Carbon Paste Electrode for the Analysis of Curcumin

Surfaces ◽  
2021 ◽  
Vol 4 (3) ◽  
pp. 191-204
Author(s):  
Edwin S. D’Souza ◽  
Jamballi G. Manjunatha ◽  
Chenthattil Raril ◽  
Girish Tigari ◽  
Huligerepura J. Arpitha ◽  
...  
Keyword(s):  
Carbon Paste Electrode ◽  
Limit Of Detection ◽  
Phosphate Buffer Solution ◽  
Modified Carbon Paste Electrode ◽  
Carbon Paste ◽  
Buffer Solution ◽  
Solution Ph ◽  
Real Sample Analysis ◽  
Titan Yellow ◽  
Paste Electrode

A modest, efficient, and sensitive chemically modified electrode was fabricated for sensing curcumin (CRC) through an electrochemically polymerized titan yellow (TY) modified carbon paste electrode (PTYMCPE) in phosphate buffer solution (pH 7.0). Cyclic voltammetry (CV) linear sweep voltammetry (LSV) and differential pulse voltammetry (DPV) approaches were used for CRC detection. PTYMCPE interaction with CRC suggests that the electrode exhibits admirable electrochemical response as compared to bare carbon paste electrode (BCPE). Under the optimized circumstances, a linear response of the electrode was observed for CRC in the concentration range 2 × 10−6 M to 10 × 10−6 M with a limit of detection (LOD) of 10.94 × 10−7 M. Moreover, the effort explains that the PTYMCPE electrode has a hopeful approach for the electrochemical resolution of biologically significant compounds. Additionally, the proposed electrode has demonstrated many advantages such as easy preparation, elevated sensitivity, stability, and enhanced catalytic activity, and can be successfully applied in real sample analysis.

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