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Amperometric Determination of Ascorbic Acid in Pharmaceutical Formulations by a Reduced Graphene Oxide-cobalt Hexacyanoferrate Nanocomposite.

Heli H - Iran J Pharm Res (2015)

Bottom Line: A nanocomposite of reduced graphene oxide-cobalt hexacyanoferrate was synthesized by a simple precipitation route.Scanning electron microscopy revealed that the nanocomposite comprised nanoparticles of cobalt hexacyanoferrate attached to the reduced graphene oxide nanosheets.Finally, an amperometric method was developed for the quantification of ascorbic acid in different pharmaceutical formulations.

View Article: PubMed Central - PubMed

Affiliation: Nanomedicine and Nanobiology Research Center, Shiraz University of Medical Sciences , Shiraz, Iran. ; Department of Nanomedicine, School of Advanced Medical Sciences and Technologies, Shiraz University of Medical Sciences, Shiraz, Iran.

ABSTRACT
Investigation of the redox properties of drugs and their determination are performed by electrochemical techniques. Data obtained from electrochemical techniques are often correlated with molecular structure and pharmacological activity of drugs. In this regard, different modified electrodes were applied as sensors for quantification of different drugs. A nanocomposite of reduced graphene oxide-cobalt hexacyanoferrate was synthesized by a simple precipitation route. Scanning electron microscopy revealed that the nanocomposite comprised nanoparticles of cobalt hexacyanoferrate attached to the reduced graphene oxide nanosheets. A nanocomposite-modified carbon paste electrode was then fabricated. It represented prominent activity toward the electrocatalytic oxidation of ascorbic acid, and the kinetics of the electrooxidation process was evaluated. Finally, an amperometric method was developed for the quantification of ascorbic acid in different pharmaceutical formulations.

No MeSH data available.


Related in: MedlinePlus

Cyclic voltammograms of UCPE (A) and MCPE (B) recorded in the absence (curve a) and presence (curve b) of 3.75 10-4 M AA in PBS.
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Figure 3: Cyclic voltammograms of UCPE (A) and MCPE (B) recorded in the absence (curve a) and presence (curve b) of 3.75 10-4 M AA in PBS.

Mentions: Cyclic voltammograms of UCPE and MCPE recorded in the absence and presence of 3.7510-4 M AA in PBS is shown in Figure 3. AA was oxidized on the UCPE surface and generated a broad anodic peak. In the case of MCPE, AA caused an increment in the anodic current of couple I and a decrement in the corresponding cathodic current occurred while the peak currents of couple II almost remained constant (concerning the currents correcting with respect to the baseline current). The anodic charge of couple I in the presence of AA is >10 times higher than the corresponding cathodic charge. The anodic and cathodic charges in the absence of AA are almost the same. These results indicate that AA was oxidized by the Co(III) moiety during couple I through a cyclic mediation redox process (an electrocatalytic oxidation mechanism). Different valence cobalt species are immobilized on the electrode surface, and the species with the higher valence (Co(III)) oxidizes AA via a chemical reaction followed by generation of low-valence (Co(II)) species. Then, the high-valence species is regenerated through the external electrical circuit. Accordingly, AA is oxidized via an electrocatalytic (EC’) process. Moreover, the current in the reverse sweep indicates that the reaction of AA with the high-valence species is the rate-determining step of the oxidation process. It should be noted that although AA is electro reactive on the UCPE surface via a direct electron transfer process, it is oxidized at lower potentials and generates higher electro oxidation current on the MCPE surface. Therefore, MCPE better oxidizes AA than UCPE from both thermodynamic and kinetic points of view. Based on the presented results, the electrocatalytic oxidation of AA on the MCPE surface can be expressed as:


Amperometric Determination of Ascorbic Acid in Pharmaceutical Formulations by a Reduced Graphene Oxide-cobalt Hexacyanoferrate Nanocomposite.

Heli H - Iran J Pharm Res (2015)

Cyclic voltammograms of UCPE (A) and MCPE (B) recorded in the absence (curve a) and presence (curve b) of 3.75 10-4 M AA in PBS.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4403061&req=5

Figure 3: Cyclic voltammograms of UCPE (A) and MCPE (B) recorded in the absence (curve a) and presence (curve b) of 3.75 10-4 M AA in PBS.
Mentions: Cyclic voltammograms of UCPE and MCPE recorded in the absence and presence of 3.7510-4 M AA in PBS is shown in Figure 3. AA was oxidized on the UCPE surface and generated a broad anodic peak. In the case of MCPE, AA caused an increment in the anodic current of couple I and a decrement in the corresponding cathodic current occurred while the peak currents of couple II almost remained constant (concerning the currents correcting with respect to the baseline current). The anodic charge of couple I in the presence of AA is >10 times higher than the corresponding cathodic charge. The anodic and cathodic charges in the absence of AA are almost the same. These results indicate that AA was oxidized by the Co(III) moiety during couple I through a cyclic mediation redox process (an electrocatalytic oxidation mechanism). Different valence cobalt species are immobilized on the electrode surface, and the species with the higher valence (Co(III)) oxidizes AA via a chemical reaction followed by generation of low-valence (Co(II)) species. Then, the high-valence species is regenerated through the external electrical circuit. Accordingly, AA is oxidized via an electrocatalytic (EC’) process. Moreover, the current in the reverse sweep indicates that the reaction of AA with the high-valence species is the rate-determining step of the oxidation process. It should be noted that although AA is electro reactive on the UCPE surface via a direct electron transfer process, it is oxidized at lower potentials and generates higher electro oxidation current on the MCPE surface. Therefore, MCPE better oxidizes AA than UCPE from both thermodynamic and kinetic points of view. Based on the presented results, the electrocatalytic oxidation of AA on the MCPE surface can be expressed as:

Bottom Line: A nanocomposite of reduced graphene oxide-cobalt hexacyanoferrate was synthesized by a simple precipitation route.Scanning electron microscopy revealed that the nanocomposite comprised nanoparticles of cobalt hexacyanoferrate attached to the reduced graphene oxide nanosheets.Finally, an amperometric method was developed for the quantification of ascorbic acid in different pharmaceutical formulations.

View Article: PubMed Central - PubMed

Affiliation: Nanomedicine and Nanobiology Research Center, Shiraz University of Medical Sciences , Shiraz, Iran. ; Department of Nanomedicine, School of Advanced Medical Sciences and Technologies, Shiraz University of Medical Sciences, Shiraz, Iran.

ABSTRACT
Investigation of the redox properties of drugs and their determination are performed by electrochemical techniques. Data obtained from electrochemical techniques are often correlated with molecular structure and pharmacological activity of drugs. In this regard, different modified electrodes were applied as sensors for quantification of different drugs. A nanocomposite of reduced graphene oxide-cobalt hexacyanoferrate was synthesized by a simple precipitation route. Scanning electron microscopy revealed that the nanocomposite comprised nanoparticles of cobalt hexacyanoferrate attached to the reduced graphene oxide nanosheets. A nanocomposite-modified carbon paste electrode was then fabricated. It represented prominent activity toward the electrocatalytic oxidation of ascorbic acid, and the kinetics of the electrooxidation process was evaluated. Finally, an amperometric method was developed for the quantification of ascorbic acid in different pharmaceutical formulations.

No MeSH data available.


Related in: MedlinePlus