scholarly journals New Methylene Blue Covalently Functionalized Graphene Oxide Nanocomposite as Interfacial Material for the Electroanalysis of Hydrogen Peroxide

2021 ◽  
Vol 9 ◽  
Author(s):  
Jifang Chen ◽  
Ziqing Gao ◽  
Ruonan Yang ◽  
Huiling Jiang ◽  
Lin Bai ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Methylene Blue ◽  
Graphene Oxide ◽  
Electrochemical Sensor ◽  
Limit Of Detection ◽  
Crosslinking Agent ◽  
Spectroscopic Techniques ◽  
Experimental Conditions ◽  
Functionalized Graphene Oxide

New methylene blue (NMB), a phenothiazine dye, was covalently bonded to graphene oxide (GO) using glutaraldehyde as a crosslinking agent, which was characterized by spectroscopic techniques and electrochemistry. The obtained GO–NMB nanocomposite was used as interface material to construct a novel electrochemical sensor for the determination of hydrogen peroxide (H2O2). The electrochemical sensor based on GO–NMB nanocomposite exhibited excellent electrocatalytic activity for the reduction of hydrogen peroxide (H2O2), which was also enhanced by GO within the GO–NMB nanocomposite. With the optimized experimental conditions, the developed sensor showed high sensitivity (79.4 μA mM−1 cm−2) for electrocatalytic determination of H2O2 at the applied potential of −0.50 V in the concentration range of 0.000333 to 2.28 mΜ. The low limit of detection (1.35 μM), good reproducibility, and high stability of the sensor suggests that the electrochemical sensor based on the GO–NMB nanocomposite possesses obvious advantages, which paves a new avenue to functionalize GO for obtaining electrode interface materials.

scholarly journals Immobilization-Free Electrochemical Sensor Coupled with a Graphene-Oxide-Based Aptasensor for Glycated Albumin Detection

Biosensors ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 85
Author(s):  
Wassa Waiwinya ◽  
Thitirat Putnin ◽  
Dechnarong Pimalai ◽  
Wireeya Chawjiraphan ◽  
Nuankanya Sathirapongsasuti ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Electrochemical Sensor ◽  
Detection Method ◽  
Limit Of Detection ◽  
Glycated Albumin ◽  
Cost Effective ◽  
Logarithmic Scale ◽  
Electrochemical Aptasensor ◽  
Alternative Approach

An immobilization-free electrochemical sensor coupled with a graphene oxide (GO)-based aptasensor was developed for glycated human serum albumin (GHSA) detection. The concentration of GHSA was monitored by measuring the electrochemical response of free GO and aptamer-bound GO in the presence of glycated albumin; their currents served as the analytical signals. The electrochemical aptasensor exhibited good performance with a base-10 logarithmic scale. The calibration curve was achieved in the range of 0.01–50 µg/mL. The limit of detection (LOD) was 8.70 ng/mL. The developed method was considered a one-drop measurement process because a fabrication step and the probe-immobilization process were not required. This simple sensor offers a cost-effective, rapid, and sensitive detection method, and could be an alternative approach for determination of GHSA levels.

scholarly journals Detection of dopamine by a minimized electrochemical sensor using a graphene oxide molecularly imprinted polymer modified micropipette tip shaped graphite electrode

2021 ◽  
pp. 174751982198995
Author(s):  
Yi Wang ◽  
Jianshe Tang ◽  
Li Xiang
Keyword(s):  
Graphene Oxide ◽  
Electrochemical Sensor ◽  
Molecularly Imprinted Polymer ◽  
Carbon Paste Electrode ◽  
Limit Of Detection ◽  
Carbon Paste ◽  
Imprinted Polymer ◽  
Molecularly Imprinted ◽  
Paste Electrode

A simple and efficient electrochemical sensor based on a homemade reshaped micropipette tip carbon paste electrode is reported. Molecularly imprinted polymer membranes of graphene oxide and polypyrrole are synthesized and modified on the surface of micropipette tip carbon paste electrode. The merit of the method is evaluated under optimized conditions via differential pulse voltammetrics. The prepared sensor exhibits remarkable sensitivity toward dopamine with a linear range of 6.4 × 10−8–2 × 10−4 M, with a limit of detection as low as 1 × 10−8 M. The proposed method is applied for the determination of dopamine in urine samples by the standard addition route. A range of 1 × 10−7–1 × 10−4 M is obtained from these samples. The relative recoveries are in the range of 95.2%–104%. The proposed method has acceptable performance for the determination of dopamine in real samples with excellent sensitivity and selectivity.

scholarly journals Analytical application of the reaction system disulphonated hydroquinone-hydrogen peroxide for the kinetic spectrophotometric determination of iron traces in acidic media

2019 ◽  
Vol 73 (6) ◽  
pp. 387-396
Author(s):  
Snezana Tosic ◽  
Snezana Mitic ◽  
Aleksandra Pavlovic ◽  
Emilija Pecev-Marinkovic ◽  
Danijela Kostic ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Limit Of Detection ◽  
Reaction System ◽  
Absorption Spectrometry ◽  
Acidic Media ◽  
Experimental Conditions ◽  
Method Effects ◽  
Kinetic Spectrophotometric ◽  
White Radish

A simple, rapid, sensitive and selective kinetic spectrophotometric method for determination of Fe(III) traces was elaborated in this paper. It is based on the catalytic effect of Fe(III) ions on oxidation of potassium salt of disulphonated hydroquinone (K2S2Hy) by hydrogen peroxide in acidic media, at a constant ionic strength. At the working temperature of 20?C and the wavelength of 450.0 nm, optimal conditions for determination of iron were found so that iron (III) can be determined by the proposed method in the concentration range of 1.87 to 18.7 ng cm-3. Corresponding RSD values were determined to be in the range 4.22 to 10.33 %. The limit of detection (LOD) calculated in two ways was found to be 1.07 ng cm-3 i.e. 1.11 ng cm-3 Fe(III). In order to assess the selectivity of the method effects of different ions on the reaction rate were also determined. It was found that presence of oxalates and citrates in the w/w ratio to Fe(III) 1:1 under selected experimental conditions interferes with determination of iron. Then the method was applied for determination of Fe(III) traces in white radish juice. The results agreed well with those obtained by atomic absorption spectrometry.

scholarly journals Simultaneous Determination of Uric Acid and Xanthine Using a Poly(Methylene Blue) and Electrochemically Reduced Graphene Oxide Composite Film Modified Electrode

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Gen Liu ◽  
Wei Ma ◽  
Yan Luo ◽  
Deng-ming Sun ◽  
Shuang Shao
Keyword(s):  
Methylene Blue ◽  
Uric Acid ◽  
Graphene Oxide ◽  
Composite Film ◽  
Simultaneous Determination ◽  
Reduced Graphene Oxide ◽  
Modified Electrode ◽  
Reduced Graphene ◽  
Electrochemically Reduced Graphene Oxide

Poly(methylene blue) and electrochemically reduced graphene oxide composite film modified electrode (PMB-ERGO/GCE) was successfully fabricated by electropolymerization and was used for simultaneous determination of uric acid (UA) and xanthine (Xa). Based on the excellent electrocatalytic activity of PMB-ERGO/GCE, the electrochemical behaviors of UA and Xa were studied by cyclic voltammetry (CV) and square wave voltammetry (SWV). Two anodic sensitive peaks at 0.630 V (versus Ag/AgCl) for UA and 1.006 V (versus Ag/AgCl) for Xa were given by CV in pH 3.0 phosphate buffer. The calibration curves for UA and Xa were obtained in the range of 8.00 × 10−8~4.00 × 10−4 M and 1.00 × 10−7~4.00 × 10−4 M, respectively, by SWV. The detection limits for UA and Xa were3.00×10-8 M and5.00×10-8 M, respectively. Finally, the proposed method was applied to simultaneously determine UA and Xa in human urine with good selectivity and high sensitivity.

scholarly journals Determination of cobalt in water samples by atomic absorption spectrometry after pre-concentration with a simple ionic liquid-based dispersive liquid-liquid micro-extraction methodology

2010 ◽  
Vol 8 (3) ◽  
pp. 617-625 ◽  
Author(s):  
Hossein Abdolmohammad-Zadeh ◽  
Elnaz Ebrahimzadeh
Keyword(s):  
Ionic Liquid ◽  
Atomic Absorption Spectrometry ◽  
Atomic Absorption ◽  
Water Samples ◽  
Limit Of Detection ◽  
Absorption Spectrometry ◽  
Experimental Conditions ◽  
Flame Atomic Absorption ◽  
Relative Standard

AbstractA rapid dispersive liquid-liquid micro-extraction (DLLME) methodology based on the application of 1-hexylpyridinium hexafluorophosphate [C6py][PF6] ionic liquid (IL) as an extractant solvent was applied for the pre-concentration of trace levels of cobalt prior to determination by flame atomic absorption spectrometry (FAAS). 1-Phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP) was employed as a chelator forming a Co-PMBP complex to extract cobalt ions from aqueous solution into the fine droplets of [C6py][PF6]. Some effective factors that influence the micro-extraction efficiency include the pH, the PMBP concentration, the amount of ionic liquid, the ionic strength, the temperature and the centrifugation time which were investigated and optimized. In the optimum experimental conditions, the limit of detection (3s) and the enrichment factor were 0.70 µg L−1 and 60, respectively. The relative standard deviation (RSD) for six replicate determinations of 50 µg L−1 Co was 2.36%. The calibration graph using the pre-concentration system was linear at levels 2–166 µg L−1 with a correlation coefficient of 0.9982. The applicability of the proposed method was evaluated by the determination of trace amounts of cobalt in several water samples.

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