Cyclic voltammetry of natural flavonoids on MWNT-modified electrode and their determination in pharmaceuticals

2011 ◽  
Vol 76 (12) ◽  
pp. 1619-1631 ◽  
Author(s):  
Guzel Ziyatdinova ◽  
Ilmira Aytuganova ◽  
Alfiya Nizamova ◽  
Mikhail Morozov ◽  
Herman Budnikov
Keyword(s):  
Cyclic Voltammetry ◽  
Dynamic Range ◽  
Phosphate Buffer Solution ◽  
Cyclic Voltammograms ◽  
Buffer Solution ◽  
Coulometric Determination ◽  
Average Roughness ◽  
Pharmaceutical Dosage Forms ◽  
Force Microscopy ◽  
Relative Standard

The determination of rutin, quercetin and taxifolin in pharmaceutical dosage forms using cyclic voltammetry on multi-walled carbon nanotube modified glassy carbon electrode (MWNT-GCE) has been developed. The surface of the electrode created has been characterized by atomic force microscopy. Electrode modification with MWNT increases the surface average roughness (190-fold) and structures it. There are two oxidation steps at 0.22 and 0.80, 0.23 and 0.80, 0.26 and 0.86 V on cyclic voltammograms of taxifolin, quercetin and rutin, respectively, in phosphate buffer solution of pH 7.4. The linear dynamic range is 1.4–28 and 28–210, 2.0–220 and 0.52–210 μM with detection limits of 0.71, 1.0 and 0.26 μM for rutin, quercetin and taxifolin, respectively. The relative standard deviation of flavonoids determination in pharmaceuticals does not exceed of 7%. The data obtained are in good agreement with coulometric determination.

scholarly journals Spectrophotometric and RP-HPLC Methods for Determining Cefotaxime Sodium in Pharmaceutical Preparations

2020 ◽  
Vol 32 (6) ◽  
pp. 1314-1320
Author(s):  
Lamya A. Sarsam ◽  
Salim A. Mohammed ◽  
Sahar A. Fathe
Keyword(s):  
Limit Of Detection ◽  
Phosphate Buffer Solution ◽  
Pharmaceutical Preparations ◽  
Molar Absorptivity ◽  
Hplc Method ◽  
Buffer Solution ◽  
Limit Of Quantification ◽  
Rp Hplc ◽  
Relative Standard

A rapid, simple and sensitive spectrophotometric and RP-HPLC methods have been developed for the quantitative determination of cefotaxime-Na in both pure and dosage forms. The spectrophotometric method was based on diazotization of cefotaxime-Na and then coupling with 8-hydroxyquinoline in an alkaline medium. The resulting azo dye exhibited maximum absorption at 551 nm with a molar absorptivity of 0.597 × 104 L mol-1 cm-1. Beer′s law was obeyed over the range 10-700 μg/25 mL (i.e. 0.4-28.0 ppm) with an excellent determination coefficient (R2 = 0.9993). The limit of detection (LOD) and limit of quantification (LOQ) were found to be 0.0194 and 0.3765 μg mL-1, respectively. The recoveries were obtained in the range 97.3-102.5% and the relative standard deviation (RSD) was better than ± 1.56. The HPLC method has been developed for the determination of cefotaxime-Na. The analysis were carried out on a C18 column and a mobile phase composed of acetonitrile and phosphate buffer solution (0.024M KH2PO4 and 0.01M H3PO4) at pH 3.5 in the ratio of 60:40 (v:v), with a flow rate of 1.0 mL min-1 and UV detection at 258 nm. The proposed method showed good linearity (in a range of concentration 1.0-200 μg mL-1. The recovery percent and a relative standard deviations were found in the range 96 to 104.8% and ± 0.017 to ± 0.031%, respectively. Both methods were applied successfully to the assay of cefotaxime-Na in commercial injection preparations.

Electroanalysis of nicotine at an electroreduced carboxylated graphene modified glassy carbon electrode

2015 ◽  
Vol 7 (3) ◽  
pp. 1147-1153 ◽  
Author(s):  
Hualing Xiao ◽  
Lingen Sun ◽  
Hongling Yan ◽  
Wen Wang ◽  
Jiali Liu ◽  
...  
Keyword(s):  
Cyclic Voltammetry ◽  
Glassy Carbon Electrode ◽  
Glassy Carbon ◽  
Phosphate Buffer ◽  
Phosphate Buffer Solution ◽  
Carbon Electrode ◽  
Modified Glassy Carbon Electrode ◽  
Buffer Solution

Nicotine is determined at a glassy carbon electrode modified with partially electroreduced carboxylated graphene by cyclic voltammetry and semi-derivative treatment after enrichment at −1.1 V in 0.1 M pH 7.0 phosphate buffer solution.

A Hydrogen Peroxide Biosensor Based on Peroxidase Activity of Hemoglobin in Polymeric Film

2007 ◽  
Vol 7 (11) ◽  
pp. 4005-4008 ◽  
Author(s):  
A. K. M. Kafi ◽  
Dong-Yun Lee ◽  
Sang-Hyun Park ◽  
Young-Soo Kwon
Keyword(s):  
Hydrogen Peroxide ◽  
Phosphate Buffer Solution ◽  
Amperometric Detection ◽  
Buffer Solution ◽  
Long Term Stability ◽  
Sensor Performance ◽  
Redox Peak ◽  
Relative Standard ◽  
Optimized Conditions

A Hydrogen peroxide (H2O2) biosensor, based on hemoglobin (Hb) and ortho-phenylenediamine (o-PD) gold electrode, was fabricated. Hb was immobilized onto the electrode surface by electrochemical polymerize method with o-PD. The designed biosensor showed a well defined redox peak which was attributed to the direct electrochemical response of Hb. The immobilized Hb exhibited an excellent electrocatalytical response to the reduction of hydrogen peroxide, enabling the sensitivity determination of H2O2. Factors and performances such as pH, potential, influencing the designed biosensor, were studied carefully. The amperometric detection of H2O2 was carried out at −300 mV in phosphate buffer solution (PBS) (0.1 M) with pH 6.0. This biosensor showed a fast amperometric response (less then 5 s) to H2O2. The levels of the (Relative standard deviation) RSDs (<3 5%) for the entire analyses reflected a highly reproducible sensor performance. Using the optimized conditions, the detection limit of the biosensor was 1 × 10−7 M and linear range was from 5 × 10−6 to 1.25 × 10−4 M. In addition, this sensor showed long term stability and good sensitivity.

scholarly journals Synthesis of Polypyrrole Inverse Opal in [bmim]PF6-Containing Acetonitrile and the Application of the Inverse Opal in Cell Prototype

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Wei Yan ◽  
Qi-Qi Dong ◽  
Li-Ning Sun ◽  
Wei Deng ◽  
Shaoping Wu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Phosphate Buffer Solution ◽  
Open Circuit ◽  
Acetonitrile Solution ◽  
Cyclic Voltammograms ◽  
Inverse Opal ◽  
Buffer Solution ◽  
Metallic Oxide ◽  
Experimental Conditions ◽  
Inverse Opals

Most primary cells use Zn or Li as the anode, a metallic oxide as the cathode, and an acidic or alkaline solution or moist past as the electrolytic solution. In this paper, highly ordered polypyrrole (PPy) inverse opals have been successfully synthesized in the acetonitrile solution containing [bmim]PF6. PPy films were prepared under the same experimental conditions. Cyclic voltammograms of the PPy film and the PPy inverse opal in neutral phosphate buffer solution (PBS) were recorded. X-ray photoelectron spectroscopy technique was used to investigate the structural surface of the PPy films and the PPy inverse opals. It is found that thePF6-anions kept dedoping from the PPy films during the potential scanning process, resulting in the electrochemical inactivity. AlthoughPF6-anions also kept dedoping from the PPy inverse opals, thePO43-anions from PBS could dope into the inverse opal, explaining why the PPy inverse opals kept their electrochemical activity. An environmental friendly cell prototype was constructed, using the PPy inverse opal as the anode. The electrolytes in both the cathodic and anodic half-cells were neutral PBSs. The open-circuit potential of the cell prototype reached 0.487 V and showed a stable output over several hundred hours.

Photoelectrochemical Sensing of Hydrazine Based on Palladium Film Modifying N-Silicon Electrode under Visible Irradiation

2014 ◽  
Vol 1006-1007 ◽  
pp. 811-814
Author(s):  
Huai Xiang Li ◽  
Jin Chao Hu ◽  
Qiong Wu ◽  
Wen Hua Song
Keyword(s):  
Cyclic Voltammetry ◽  
Electron Microscope ◽  
Modified Electrode ◽  
Photoelectron Spectroscopy ◽  
Phosphate Buffer Solution ◽  
Buffer Solution ◽  
X Ray ◽  
Visible Irradiation ◽  
Photo Electrode ◽  
Scanning Electron

In this work, a palladium film has been evaporated on an n-silicon (n-n+-Si) surface and electrochemically activated by cyclic voltammetry (CV) to form a modified silicon photo-electrode. Scanning electron microscope (SEM) and x-ray photoelectron spectroscopy (XPS) were used to characterize the morphology and composition of the modified electrode surface. A new photoelectrochemical (PEC) cell based on the modified electrode was used as sensor for hydrazine determination by photocurrent measurements. The sensor showed good photocurrent responses by adding different concentrations of hydrazine with a good stability. The linear ranges for the detection of hydrazine are 2 to 20 μM with a detection limit of 0.5 μM in pH=7.0 phosphate buffer solution (PBS).

scholarly journals A simple optical pH sensor based on pectin and Ruellia tuberosa L-derived anthocyanin for fish freshness monitoring

F1000Research ◽  
2021 ◽  
Vol 10 ◽  
pp. 422
Author(s):  
Nazaruddin Nazaruddin ◽  
Nurul Afifah ◽  
Muhammad Bahi ◽  
Susilawati Susilawati ◽  
Nor Diyana Md. Sani ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Room Temperature ◽  
Ph Value ◽  
Ph Sensor ◽  
Phosphate Buffer Solution ◽  
Good Sensitivity ◽  
Buffer Solution ◽  
C Storage ◽  
Relative Standard ◽  
Optical Ph Sensor

A simple optical pH sensor using the active compound anthocyanin (ACN), derived Ruellia tuberosa L. flower immobilized in a pectin membrane matrix, was been fabricated and employed to monitor the freshness of tilapia fish at room temperature and 4oC storage. The optimum pectin weight and ACN concentrations were 0.1% and 0.025 mg/L. The sensor showed good sensitivity at 0.03 M phosphate buffer solution. The sensor’s reproducibility was evaluated using 10 replicate sensors where a standard deviation of 0.045 or relative standard deviation of 9.15 was achieved. The sensor displayed an excellent response after 10 minutes of exposure, possessing a response stability for 10 consecutive days. The decrease in pH value of the Tilapia fish from 7.3 to 5 was observed in a 48 hour test, which can be used as the parameter when monitoring fish freshness.

scholarly journals Development of Methanol Sensor Based on Sol-Gel Drop-Coating Co3O4·CdO·ZnO Nanoparticles Modified Gold-Coated µ-Chip by Electro-Oxidation Process

Gels ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 235
Author(s):  
Mohammed M. Rahman ◽  
Jahir Ahmed ◽  
Abdullah M. Asiri ◽  
Sulaiman Y.M. Alfaifi ◽  
Hadi. M. Marwani
Keyword(s):  
Photoelectron Spectroscopy ◽  
Metallic Nanoparticles ◽  
Dynamic Range ◽  
Sol Gel ◽  
Phosphate Buffer Solution ◽  
Fast Response ◽  
Buffer Solution ◽  
Metallic Oxide ◽  
X Ray ◽  
Methanol Sensor

Herein, novel Co3O4·CdO·ZnO-based tri-metallic oxide nanoparticles (CCZ) were synthesized by a simple solution method in basic phase. We have used Fourier Transform Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Field Emission Scanning Electron Microscope (FESEM), Dynamic Light Scattering (DLS), Tunneling Electron Microscopy (TEM), and Energy-Dispersive Spectroscopy (EDS) techniques to characterize the CCZ nanoparticles. XRD, TEM, DLS, and FESEM investigations have confirmed the tri-metallic nanoparticles’ structure, while XPS and EDS analyses have shown the elemental compositions of the CCZ nanoparticles. Later, a Au/μ-Chip was modified with the CCZ nanoparticles using a conducting binder, PEDOT: PSS (poly(3,4-ethylenedioxythiophene) polystyrene sulfonate) in a sol-gel system, and dried completely in air. Then, the CCZ/Au/μ-Chip sensor was used to detect methanol (MeOH) in phosphate buffer solution (PBS). Outstanding sensing performance was achieved for the CCZ/Au/μ-Chip sensor, such as excellent sensitivity (1.3842 µAµM−1cm−2), a wide linear dynamic range of 1.0 nM–2.0 mM (R2 = 0.9992), an ultra-low detection limit (32.8 ± 0.1 pM at S/N = 3), a fast response time (~11 s), and excellent reproducibility and repeatability. This CCZ/Au/μ-Chip sensor was further applied with appropriate quantification results in real environmental sample analyses.

scholarly journals Polymethionine modified carbon nanotube sensor for sensitive and selective determination of L-tryptophan

2020 ◽  
Vol 10 (4) ◽  
pp. 305-315
Author(s):  
Nambudumada S. Prinith ◽  
Jamballi G. Manjunatha
Keyword(s):  
Cyclic Voltammetry ◽  
Carbon Nanotube ◽  
Phosphate Buffer Solution ◽  
Calibration Plot ◽  
Linear Segment ◽  
Current Signal ◽  
Buffer Solution ◽  
Detection Range ◽  
Selective Determination

The electrochemically initiated catalytic oxidation of amino acid L-tryptophan (L-TPN) in phosphate buffer solution has been scrutinized using highly conductive polymethionine modified carbon nanotube paste sensor (PMETCNTPS) through cyclic voltammetry (CV) technique. Compared to the bare carbon nanotube paste sensor (BCNTPS), PMETCNTPS exhibited a quantifiable current signal by CV method. PMETCNTPS was found sensitive to L-TPN concentrations within the linear segment of detection range 1.5 - 8.0×10-5 M. By employing the calibration plot, the detection limit was determined as 6.99×10-7 M. In addition, PMETCNTPS was successfully exploited and validated in determining L-TPN in the pharmaceutical supplement.

scholarly journals Electroorganic synthesis of disulfonamide substituted p-benzoquinone by hydroquinone electrochemical oxidation

2018 ◽  
Vol 9 (1) ◽  
pp. 1-7 ◽  
Author(s):  
Seba Nassif ◽  
Deeb Bakeer ◽  
Rushdi Madwar ◽  
Waleed Khadam ◽  
Abeer Nakhla
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Synthesis ◽  
Phosphate Buffer Solution ◽  
Electrolytic Cell ◽  
Oxidation Potential ◽  
Atom Economy ◽  
Buffer Solution ◽  
Ethanol Mixture ◽  
Ece Mechanism ◽  
Green Conditions

This study illustrates electrochemical behavior of hydroquinone and 4-amino-6-chloro­benzene-1,3-disulfonamide in the phosphate buffer solution evaluated by cyclic voltammetry. It was found that the peak of the hydroquinone oxidation potential in the presence of 4-amino-6-chlorobenzene-1,3-disulfonamide is shifted to more positive values compared to hydroquinone alone.  Based on these results, the electrochemical synthesis of new disulfonamide substituted p-benzoquinone is proposed and carried out via electro­chemical oxidation of hydroquinone in the presence of 4-amino-6-chlorobenzene-1,3-di­sulfonamide in the electrolytic cell. It has been concluded that hydroquinone is converted into disulfonamide substituted p-benzoquinone via an ECE mechanism. The successful electrochemical synthesis was conducted in the water/ethanol mixture under green conditions without any toxic reagents or solvents and with high atom economy.

scholarly journals Lanthanum Ortho-Ferrite (LaFeO3) Nano-Particles Based Electrochemical Sensor for the Detection of Dopamine

2020 ◽  
Vol 10 (5) ◽  
pp. 6182-6188
Keyword(s):  
Cyclic Voltammetry ◽  
Electrochemical Sensor ◽  
Differential Pulse Voltammetry ◽  
Phosphate Buffer Solution ◽  
Differential Pulse ◽  
Nano Particles ◽  
Ferric Nitrate ◽  
Buffer Solution ◽  
Pulse Voltammetry ◽  
Modified Sensor

The perovskite type lanthanum ortho ferrite nano-particles (LaFeO3) based electrochemical sensor was developed and used to detect dopamine. For this work the lanthanum ortho ferrite nano-particles (LaFeO3) were synthesized by combustion technique using sugar and ethanolamine with lanthanum oxide and ferric nitrate. For the characterization of newly prepared lanthanum ortho ferrite nano-particles, techniques like FESEM, and TEM were used. The crystallite size was found to be 40 to 46 nm with cubic crystal structure. To check the electrochemical properties of a modified sensor electrode (LaFeO3/GP), the cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques were used. During the experiment, the phosphate buffer solution having pH 6.0 was employed, maintaining the scan rate 100mVs-1 and 50mVs-1 for cyclic voltammetry and Differential pulse voltammetry, respectively.

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