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Electro-oxidation mechanism and direct square-wave voltammetric determination of lidocaine with a carbon-paste electrode.

Rahbar N, Ramezani Z, Babapour A - Jundishapur J Nat Pharm Prod (2015)

Bottom Line: The limit of detection (LOD) was 0.29 μmol L(-1).The results of this study show that LH in different pharmaceutical preparations could be determined with good reliability.In addition, the results reveal that the equal numbers of electrons and protons are involved in the oxidation of LH and the irreversible oxidation of an analyte was performed via amine groups of LH molecule.

View Article: PubMed Central - PubMed

Affiliation: Nanotechnology Research Center, School of Pharmacy, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran ; Department of Medicinal Chemistry, School of Pharmacy, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran.

ABSTRACT

Background: Lidocaine hydrochloride (LH) is one of the most extensively used local anesthetics and peripheral analgesics. Availability of a simple and sensitive assay method for this analyte in pharmaceutical preparations as well as development of new voltammetric detectors that can be applied in chromatographic systems for determination of this analyte in biological samples are of great importance.

Objectives: In this study, a square-wave voltammetric (SWV) determination of LH at a bare carbon-paste electrode (CPE) was reported. Moreover, the oxidation mechanism for LH molecule at this electrode was investigated.

Materials and methods: The SW voltammogram of LH solution at CPE showed a well-defined peak between +0.80 and +0.88 V depending on a scan rate in potassium nitrate (KNO3) solution. Different chemical and instrumental parameters influencing the voltammetric response, such as the pH level and scan rate were optimized for LH determination.

Results: A linear range of 8.0 - 1000.0 μmol L(-1) (r(2) = 0.999) was obtained. The limit of detection (LOD) was 0.29 μmol L(-1). The relative standard deviations of 2.1% obtained for 0.8 800 μmol L(-1) solution of LH indicated a reasonable reproducibility of the method.

Conclusions: The results of this study show that LH in different pharmaceutical preparations could be determined with good reliability. In addition, the results reveal that the equal numbers of electrons and protons are involved in the oxidation of LH and the irreversible oxidation of an analyte was performed via amine groups of LH molecule.

No MeSH data available.


A) SW voltammograms of LH solution at different potential scan rates within the range of 10-300 mV s-1. B) The plot of peak current vs. scan rate. C) The plot of log of peak current vs. log of scan rate. D) The plot of peak current vs. square root of scan rate. E) The plot of peak potential vs. log of scan rate. [Conditions: concentration of LH: 150 µM; pH=10.0; accumulation time: 120 s]
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fig17938: A) SW voltammograms of LH solution at different potential scan rates within the range of 10-300 mV s-1. B) The plot of peak current vs. scan rate. C) The plot of log of peak current vs. log of scan rate. D) The plot of peak current vs. square root of scan rate. E) The plot of peak potential vs. log of scan rate. [Conditions: concentration of LH: 150 µM; pH=10.0; accumulation time: 120 s]

Mentions: A study of the effect of potential sweep rate (ν) on the peak current was investigated. It helps to identify that the oxidation of LH at CPE is diffusion- or surface-controlled. Figure 5A illustrates the SW voltammograms of 150 µM LH at different scan rates within the range of 0.01 - 0.30 V s-1. It shows a linear increase in the peak current with increase in scan rate between 0.05 - 0.20 V s-1 as expected for the surface-controlled process. This linear dependency between Ip and ν (Figure 5B) can be concluded by the regression equation:


Electro-oxidation mechanism and direct square-wave voltammetric determination of lidocaine with a carbon-paste electrode.

Rahbar N, Ramezani Z, Babapour A - Jundishapur J Nat Pharm Prod (2015)

A) SW voltammograms of LH solution at different potential scan rates within the range of 10-300 mV s-1. B) The plot of peak current vs. scan rate. C) The plot of log of peak current vs. log of scan rate. D) The plot of peak current vs. square root of scan rate. E) The plot of peak potential vs. log of scan rate. [Conditions: concentration of LH: 150 µM; pH=10.0; accumulation time: 120 s]
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4379891&req=5

fig17938: A) SW voltammograms of LH solution at different potential scan rates within the range of 10-300 mV s-1. B) The plot of peak current vs. scan rate. C) The plot of log of peak current vs. log of scan rate. D) The plot of peak current vs. square root of scan rate. E) The plot of peak potential vs. log of scan rate. [Conditions: concentration of LH: 150 µM; pH=10.0; accumulation time: 120 s]
Mentions: A study of the effect of potential sweep rate (ν) on the peak current was investigated. It helps to identify that the oxidation of LH at CPE is diffusion- or surface-controlled. Figure 5A illustrates the SW voltammograms of 150 µM LH at different scan rates within the range of 0.01 - 0.30 V s-1. It shows a linear increase in the peak current with increase in scan rate between 0.05 - 0.20 V s-1 as expected for the surface-controlled process. This linear dependency between Ip and ν (Figure 5B) can be concluded by the regression equation:

Bottom Line: The limit of detection (LOD) was 0.29 μmol L(-1).The results of this study show that LH in different pharmaceutical preparations could be determined with good reliability.In addition, the results reveal that the equal numbers of electrons and protons are involved in the oxidation of LH and the irreversible oxidation of an analyte was performed via amine groups of LH molecule.

View Article: PubMed Central - PubMed

Affiliation: Nanotechnology Research Center, School of Pharmacy, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran ; Department of Medicinal Chemistry, School of Pharmacy, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, IR Iran.

ABSTRACT

Background: Lidocaine hydrochloride (LH) is one of the most extensively used local anesthetics and peripheral analgesics. Availability of a simple and sensitive assay method for this analyte in pharmaceutical preparations as well as development of new voltammetric detectors that can be applied in chromatographic systems for determination of this analyte in biological samples are of great importance.

Objectives: In this study, a square-wave voltammetric (SWV) determination of LH at a bare carbon-paste electrode (CPE) was reported. Moreover, the oxidation mechanism for LH molecule at this electrode was investigated.

Materials and methods: The SW voltammogram of LH solution at CPE showed a well-defined peak between +0.80 and +0.88 V depending on a scan rate in potassium nitrate (KNO3) solution. Different chemical and instrumental parameters influencing the voltammetric response, such as the pH level and scan rate were optimized for LH determination.

Results: A linear range of 8.0 - 1000.0 μmol L(-1) (r(2) = 0.999) was obtained. The limit of detection (LOD) was 0.29 μmol L(-1). The relative standard deviations of 2.1% obtained for 0.8 800 μmol L(-1) solution of LH indicated a reasonable reproducibility of the method.

Conclusions: The results of this study show that LH in different pharmaceutical preparations could be determined with good reliability. In addition, the results reveal that the equal numbers of electrons and protons are involved in the oxidation of LH and the irreversible oxidation of an analyte was performed via amine groups of LH molecule.

No MeSH data available.