scholarly journals Comparative Electroanalytical Studies of Graphite Flake and Multilayer Graphene Paste Electrodes

Sensors ◽  
2020 ◽  
Vol 20 (6) ◽  
pp. 1684 ◽  
Author(s):  
Natalia Festinger ◽  
Kamila Morawska ◽  
Vladimir Ivanovski ◽  
Magdalena Ziąbka ◽  
Katarzyna Jedlińska ◽  
...  

In this paper, the fabrication, surface characterisation and electrochemical properties of graphite flake (GFPE) and multilayer graphene (MLGPE) paste electrodes are described. The Raman investigations and scanning electron microscopy were used to analyze and compare structure of both carbon materials. The electroanalytical performance of both electrodes was examined and compared on the basis of the square-wave and cyclic voltammetric behavior of acetaminophen and model redox systems. Results of those studies revealed that GFPE has a larger electroactive surface area and better conductive properties, whilst MLGPE demonstrate better analytical characteristic in case of acetaminophen (AC) determination. AC determination was developed using square wave voltammetry (SWV) and square wave stripping voltammetry (SWSV). For both working electrodes, the process of accumulation enabled us to obtain an extended linear range and to lower the detection limit. In pharmaceutical formulations, AC was determined with good recovery.

2017 ◽  
Vol 240 ◽  
pp. 848-856 ◽  
Author(s):  
Mohamad Idris Saidin ◽  
Illyas Md Isa ◽  
Mustaffa Ahmad ◽  
Norhayati Hashim ◽  
Sulaiman Ab Ghani

2011 ◽  
Vol 76 (12) ◽  
pp. 1699-1715 ◽  
Author(s):  
Sławomira Skrzypek ◽  
Valentin Mirceski ◽  
Sylwia Smarzewska ◽  
Dariusz Guziejewski ◽  
Witold Ciesielski

Although 2-guanidinobenzimidazole (GBI; CAS: 5418-95-1) is a compound of biological interest, generally there is a lack of electrochemical studies and the methods of its determination. The GBI behavior at a mercury electrode was analyzed under conditions of linear sweep voltammetry (LSV), differential pulse voltammetry (DPV), square-wave voltammetry (SWV) and square-wave stripping voltammetry (SWSV). Although GBI is electrochemically inactive at mercury electrode it adsorbs at the mercury surface and catalyzes effectively the hydrogen evolution reaction. Theoretical analysis of two possible pathways, according to which the GBI electrode mechanism can be explained, is performed. Simple analysis of peak current and potential with respect to available time window, i.e. change of frequency can be helpful in discerning the character of the recorded SW current. The established electrode mechanism is assumed to involve a preceding chemical reaction in which the adsorbed catalyst (GBIads) is protonated and the protonated form of the catalyst (GBIH+(ads)) is irreversibly reduced at potential about –1.18 V vs Ag|AgCl (citrate buffer pH 2.5). New methods of voltammetric determination of 2-guanidinobenzimidazole were developed. The detection and quantifications limits were found to be 1 × 10–7, 1 × 10–6 mol l–1 (SWV); 8 × 10–8, 9 × 10–7 mol l–1 (SWSV); 4 × 10–7, 2 × 10–6 mol l–1 (DPV) and 6 × 10–7, 3 × 10–6 mol l–1 (LSV), respectively.


2004 ◽  
Vol 82 (7) ◽  
pp. 1203-1209 ◽  
Author(s):  
E Hammam ◽  
H S El-Desoky ◽  
A Tawfik ◽  
M M Ghoneim

Imatinib (GleevecTM, ST1571) exemplifies the successful development of a rationally designed molecularly targeted therapy for treatment of a specific cancer. It is a highly promising new drug for the treatment of chronic myelogenous leukemia in blast crisis, in the accelerated or chronic phase after interferon failure or intolerance. The electrochemical behavior of imatinib was studied in Britton–Robinson (B–R) buffers of pH 2 to 11 by means of cyclic voltammetry at a hanging mercury drop electrode. The voltammograms showed a single 2-electron irreversible cathodic peak, which may be attributed to reduction of the C=O double bond of the imatinib molecule. Imatinib exhibited a strong adsorption onto the electrode surface especially in B–R buffers of pH 6 and 7. The adsorptive response of the drug was optimized with respect to the pH of the electrolysis medium, accumulation variables, and instrumental parameters using a square-wave stripping voltammetry technique. A fully validated, simple, sensitive, precise, and selective square-wave adsorptive cathodic stripping voltammetric procedure is described for trace determination of imatinib. The limits of detection (LOD) and quantitation (LOQ) of the bulk imatinib, following preconcentration for 150 s onto the hanging mercury drop electrode, were found to be 2.6 × 10–10 and 8.7 × 10–10 mol/L, respectively. The proposed procedure was successfully applied for quantitation of imatinib in pharmaceutical formulation (Glivec®) and spiked human serum, without the necessity for sample pretreatment or time-consuming extraction or evaporation steps prior to analysis of the drug. LOD and LOQ of 4.6 × 10–10 and 1.5 × 10–9 mol/L, respectively, were achieved after 120 s of preconcentration of the drug spiked in human serum.Key words: imatinib, GleevecTM, Glivec®, ST1571, cyclic voltammetry, square-wave stripping voltammetry, electrochemical behavior, quantification, pharmaceutical formulation, human serum.


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