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Voltammetric Behavior and Determination of Trace Amounts of Omeprazole Using an Edge-plane Pyrolytic Graphite Electrode.

Shahrokhian S, Ghalkhani M, Bayat M, Ghorbani-Bidkorbeh F - Iran J Pharm Res (2015)

Bottom Line: The voltammetric performance of edge-plane pyrolytic graphite (EPG) electrode via adsorptive stripping voltammetry was investigated for study of the electrochemical behavior of omeprazole (OMZ) in aqueous solution.The results revealed that the oxidation of OMZ is an irreversible pH-dependent process that proceeds with the transfer of one electron and one proton in an adsorption-controlled mechanism.Simplicity, high reproducibility and low detection limit (3 nM) of the electrode response as well as wide linear range (0.01 to 4.0 µM) can be stated as significant features of this electrode.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Sharif University of Technology, Tehran, Iran . ; Institute for Nanoscience and Technology, Sharif University of Technology, Tehran, Iran .

ABSTRACT
The voltammetric performance of edge-plane pyrolytic graphite (EPG) electrode via adsorptive stripping voltammetry was investigated for study of the electrochemical behavior of omeprazole (OMZ) in aqueous solution. The results revealed that the oxidation of OMZ is an irreversible pH-dependent process that proceeds with the transfer of one electron and one proton in an adsorption-controlled mechanism. The determination conditions, such as the pH values of the supporting electrolyte, accumulation time and scan rate were optimized. Simplicity, high reproducibility and low detection limit (3 nM) of the electrode response as well as wide linear range (0.01 to 4.0 µM) can be stated as significant features of this electrode. The EPG electrode was successfully applied for the determination of OMZ in pharmaceutical formulations and satisfactory results were obtained.

No MeSH data available.


Related in: MedlinePlus

(A) LSVs of 100  M OMZ at the EPG electrode in various pHs of buffer solution (from 1 to 5: 5.0, 6.0, 7.0, 8.0, 9.0). (B) Dependence of Ep with pH solution; scan rate 100 mV s-1.
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Figure 2: (A) LSVs of 100  M OMZ at the EPG electrode in various pHs of buffer solution (from 1 to 5: 5.0, 6.0, 7.0, 8.0, 9.0). (B) Dependence of Ep with pH solution; scan rate 100 mV s-1.

Mentions: The organic electrode reaction systems always involve the proton transfer, so a buffer solution is often used as the supporting electrolyte, and the pH of the buffer solution has a direct impact on the peak shape and E1/2. Therefore, pH of buffer solution is very important. OMZ degrades in acidic solutions unless it may be protected against acid conditions (29), so a significant decomposition is observed in solutions with pH values below 5.0 with a color change of solution, so we studied solutions with pH values equal or more than 5.0. Voltammetric behavior of OMZ in buffer solutions with different pHs (from 5.0 to 9.0) was investigated on the surface of the EPG electrode (Figure 2A). A good linear relationship was observed between the Ep and pH values (in the range of 5 to 8, Figure 2B) with the equation, Ep (mV) = - 48.0 pH + 1238.5 (R² = 0.9992). It could be observed that the oxidation peak potential shifted negatively with increasing pH, which suggests that H+ participates in the oxidation process and OMZ oxidation involves the same number of electrons and protons. In solutions with a pH value greater than 8.0, the slope is changed because the mechanism itself changes to where there are no protons involved before the rate determining step. The best electrode response is achieved in buffer solutions with pH 7.0. Therefore, phosphate buffer with pH 7.0 was chosen as supporting electrolyte for further experiments.


Voltammetric Behavior and Determination of Trace Amounts of Omeprazole Using an Edge-plane Pyrolytic Graphite Electrode.

Shahrokhian S, Ghalkhani M, Bayat M, Ghorbani-Bidkorbeh F - Iran J Pharm Res (2015)

(A) LSVs of 100  M OMZ at the EPG electrode in various pHs of buffer solution (from 1 to 5: 5.0, 6.0, 7.0, 8.0, 9.0). (B) Dependence of Ep with pH solution; scan rate 100 mV s-1.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4403062&req=5

Figure 2: (A) LSVs of 100  M OMZ at the EPG electrode in various pHs of buffer solution (from 1 to 5: 5.0, 6.0, 7.0, 8.0, 9.0). (B) Dependence of Ep with pH solution; scan rate 100 mV s-1.
Mentions: The organic electrode reaction systems always involve the proton transfer, so a buffer solution is often used as the supporting electrolyte, and the pH of the buffer solution has a direct impact on the peak shape and E1/2. Therefore, pH of buffer solution is very important. OMZ degrades in acidic solutions unless it may be protected against acid conditions (29), so a significant decomposition is observed in solutions with pH values below 5.0 with a color change of solution, so we studied solutions with pH values equal or more than 5.0. Voltammetric behavior of OMZ in buffer solutions with different pHs (from 5.0 to 9.0) was investigated on the surface of the EPG electrode (Figure 2A). A good linear relationship was observed between the Ep and pH values (in the range of 5 to 8, Figure 2B) with the equation, Ep (mV) = - 48.0 pH + 1238.5 (R² = 0.9992). It could be observed that the oxidation peak potential shifted negatively with increasing pH, which suggests that H+ participates in the oxidation process and OMZ oxidation involves the same number of electrons and protons. In solutions with a pH value greater than 8.0, the slope is changed because the mechanism itself changes to where there are no protons involved before the rate determining step. The best electrode response is achieved in buffer solutions with pH 7.0. Therefore, phosphate buffer with pH 7.0 was chosen as supporting electrolyte for further experiments.

Bottom Line: The voltammetric performance of edge-plane pyrolytic graphite (EPG) electrode via adsorptive stripping voltammetry was investigated for study of the electrochemical behavior of omeprazole (OMZ) in aqueous solution.The results revealed that the oxidation of OMZ is an irreversible pH-dependent process that proceeds with the transfer of one electron and one proton in an adsorption-controlled mechanism.Simplicity, high reproducibility and low detection limit (3 nM) of the electrode response as well as wide linear range (0.01 to 4.0 µM) can be stated as significant features of this electrode.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry, Sharif University of Technology, Tehran, Iran . ; Institute for Nanoscience and Technology, Sharif University of Technology, Tehran, Iran .

ABSTRACT
The voltammetric performance of edge-plane pyrolytic graphite (EPG) electrode via adsorptive stripping voltammetry was investigated for study of the electrochemical behavior of omeprazole (OMZ) in aqueous solution. The results revealed that the oxidation of OMZ is an irreversible pH-dependent process that proceeds with the transfer of one electron and one proton in an adsorption-controlled mechanism. The determination conditions, such as the pH values of the supporting electrolyte, accumulation time and scan rate were optimized. Simplicity, high reproducibility and low detection limit (3 nM) of the electrode response as well as wide linear range (0.01 to 4.0 µM) can be stated as significant features of this electrode. The EPG electrode was successfully applied for the determination of OMZ in pharmaceutical formulations and satisfactory results were obtained.

No MeSH data available.


Related in: MedlinePlus