Amperometric determination of xanthine and hypoxanthine at carbon electrodes. Effect of surface activity and the instrumental parameters on the sensitivity and the limit of detection

Direct current voltammetric (DCV) and differential pulse voltammetric (DPV) determination of antineoplastic agent doxorubicin (DOX) at a carbon paste electrode (CPE) was developed. Britton–Robinson buffer (pH 7.0) was used as a supporting electrolyte. The limits of detection are 8 × 10–7 mol l–1 (DCV) and 6 × 10–8 mol l–1 (DPV). The accumulation of DOX at the electrode surface was used to decrease the limits of detection down to 2.2 × 10–7 mol l–1 for adsorptive stripping DC voltammetry (DCAdSV) and 2.8 × 10–9 mol l–1 for adsorptive stripping differential pulse voltammetry (DPAdSV) at CPE. The results of the voltammetric methods were utilized for the development of a new determination of doxorubicin using HPLC with amperometric detection on CPE based on spherical microparticles of glassy carbon in a wall-jet configuration. A column with chemically bonded C18 stationary phase and a mobile phase containing 0.01 M phosphate buffer (pH 5.0)–methanol 25:75 (v/v) were used. The limit of detection is 4 × 10–7 mol l–1 (HPLC with electrochemical detection (ED)).

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Simultaneous amperometric determination of malic and gluconic acids in wine using screen-printed carbon electrodes

Sensors and Actuators B Chemical ◽

10.1016/j.snb.2015.01.101 ◽

2015 ◽

Vol 211 ◽

pp. 250-254 ◽

Cited By ~ 6

Author(s):

Begoña Molinero-Abad ◽

M. Asunción Alonso-Lomillo ◽

Olga Domínguez-Renedo ◽

M. Julia Arcos-Martínez

Keyword(s):

Carbon Electrodes ◽

Amperometric Determination ◽

Screen Printed

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Voltammetric Determination of Uric Acid in Clinical Serum Samples Using DMF Modified Screen Printed Carbon Electrodes

International Journal of Electrochemistry ◽

10.1155/2019/6318515 ◽

2019 ◽

Vol 2019 ◽

pp. 1-8

Author(s):

Melaku Metto ◽

Samrawit Eramias ◽

Bekele Gelagay ◽

Alemayehu P. Washe

Keyword(s):

Uric Acid ◽

Limit Of Detection ◽

Phosphate Buffer Solution ◽

Clinical Samples ◽

Carbon Electrodes ◽

Current Response ◽

Serum Samples ◽

Relative Standard ◽

Screen Printed

Screen printed carbon electrodes (SPCEs) provide attractive opportunity for sensitive and selective determination target analytes in clinical samples. The aim of the current work was to develop SPCEs based sensor for the determination of uric acid in clinical serum samples. The electrodes were pretreated by soaking in N,N-dimethylformamide for 5 minutes followed by drying in an oven at 100°C for 20 mins. The effect of surface pretreatment was characterized using cyclic voltammetry. The current response of uric acid detection was improved by a factor of 3.5 in differential pulse voltammetric measurement compared to unmodified electrode. Under the optimized conditions, the sensor displayed two dynamic linear ranges 5-100 μM and 100-500 μM with correlation coefficient, R2, values of 0.98782 and 0.97876, respectively. The limit of detection and limit of quantification calculated using the dynamic linear range 5-100 μM were 1.9 x 10−7 M and 6.33 x 10−7 M, respectively. The developed sensor displayed well separated and discerned peaks for UA in presence of the potential interferent (ascorbic acid and citric acid). The electrode was successfully applied for the detection of very low level of UA in clinical serum samples in a phosphate buffer solution (pH = 7). The proposed sensor showed a very high reproducibility and repeatability with the relative standard deviation of 0.9%. In conclusion, a simple and low cost sensor based on SPCEs is developed for sensitive and selective detection of uric acid in clinical samples.

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Disposable stencil-printed carbon electrodes for electrochemical analysis of sildenafil citrate in commercial and adulterated tablets

Brazilian Journal of Analytical Chemistry ◽

10.30744/brjac.2179-3425.ar-65-2021 ◽

2021 ◽

Author(s):

Danielly Rocha ◽

Habdias Silva-Neto ◽

Laísa Oliveira ◽

Shellyda Souza ◽

Mário Santana ◽

...

Keyword(s):

Limit Of Detection ◽

Graphite Powder ◽

Electrochemical Analysis ◽

Sildenafil Citrate ◽

Carbon Electrodes ◽

Heterogeneous Electron Transfer ◽

Linear Behavior ◽

Electron Transfer Rate Constant ◽

3D Printed

Forensic studies are extremally important to investigate suspected adulterations of consumable products, such as Viagra®. This report describes the determination of sildenafil citrate (SC) in commercial and adulterated tablets based on square-wave voltammetry (SWV) measurements using disposable stencil-printed carbon electrodes. The conductive ink used for the manufacture of integrated electrodes was produced by combining graphite powder and glass varnish. To promote a reusable strategy for limiting the geometric area of the electrodes, a 3D-printed holder was constructed. Detailed morphological and electrochemical characterization studies revealed well-defined graphite flakes incorporated on the polymeric substrate and a faster heterogeneous electron-transfer rate constant (Ks = 1.3 × 10–3 cm s–1). Based on the analytical performance, a linear behavior was observed in a SC concentration range from 1 to 20 µmol L–1 with limit of detection equal to 0.2 µmol L–1. The selectivity of the proposed method was evaluated and the presence of potentially interfering compounds like phosphate, lactose, paracetamol and tadalafil and no difference higher than 15% was observed. The analysis of SC was performed in commercial and seized tablets and the achieved values were 50 ± 1 mg for Viagra® tablet, 54 ± 1 mg for generic formulations 38 ± 1 mg for seized tablet. In addition, the proposed method offered satisfactory accuracy (98.2 – 102.0%) no noticeable matrix effect. Lastly, considering the achieved results, the use of stencil-printed carbon electrodes and SWV has demonstrated to be a powerful and robust analytical tool for forensic investigations.

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An investigation of the influences of the background material and layer thickness of sputtered palladium/gold on carbon electrodes for the amperometric determination of hydrogen peroxide

Journal of Molecular Catalysis ◽

10.1016/0304-5102(86)87048-1 ◽

1986 ◽

Vol 38 (1-2) ◽

pp. 49-60 ◽

Cited By ~ 31

Author(s):

Lo Gorton ◽

Thomas Svensson

Keyword(s):

Hydrogen Peroxide ◽

Layer Thickness ◽

Carbon Electrodes ◽

Amperometric Determination ◽

Background Material

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Determination of epinephrine in human serum using a Pt electrode modified by polyaniline–poly(3-methylthiophene)–poly(3,3′-diaminobenzidine)

Canadian Journal of Chemistry ◽

10.1139/cjc-2015-0207 ◽

2015 ◽

Vol 93 (11) ◽

pp. 1239-1244 ◽

Cited By ~ 2

Author(s):

Emine Ülker ◽

Muammer Kavanoz

Keyword(s):

Human Serum ◽

Dynamic Range ◽

Limit Of Detection ◽

Oxidation Potential ◽

Serum Samples ◽

Pt Electrode ◽

Limit Of Quantification ◽

Amperometric Determination ◽

Best Response

A Pt electrode modified by polyaniline–poly(3-methylthiophene)–poly(3,3′-diaminobenzidine) was used for amperometric determination of epinephrine in a solution of NaHSO4/Na2SO4 (pH 2.0). For these studies, potentials between 0.40 and 0.50 V were applied, and the best response was obtained at 0.45 V. The limit of detection, limit of quantification, and the linear dynamic range were 1.23 × 10−4, 4.10 × 10−4, and 4.10 × 10−4 to 100.0 mmol L−1, respectively. These results were compared with determinations using Pt electrodes that were coated and uncoated with homopolymers. To check the accuracy of the developed method and the matrices interference, determination of epinephrine was performed in human serum samples using this modified electrode. The epinephrine concentrations were adjusted to 1.0 and 5.0 mmol L−1, and recovery values were calculated as 100.4% and 96.8%, respectively. It is significant that the determination of epinephrine was carried out at a lower potential (0.45 V) than the oxidation potential of epinephrine (0.65 V) without any matrix effect.

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