Voltammetric quantification of a nonsteroidal anti-inflammatory agent diflunisal based on the enhancement effect of cationic surfactant on boron-doped diamond electrode
At a Glance
Section titled âAt a Glanceâ| Metadata | Details |
|---|---|
| Publication Date | 2021-05-11 |
| Journal | Macedonian Journal of Chemistry and Chemical Engineering |
| Authors | ErtuÄrul Keskin, Shabnam Allahverdiyeva, Amer S. Alali, Yavuz Yardım |
| Institutions | Adıyaman University, Van YĂŒzĂŒncĂŒ Yıl Ăniversitesi |
| Citations | 5 |
| Analysis | Full AI Review Included |
Executive Summary
Section titled âExecutive SummaryâThis research details a highly sensitive and practical voltammetric method for quantifying the nonsteroidal anti-inflammatory drug Diflunisal (DIF) using a Boron-Doped Diamond (BDD) electrode.
- Core Innovation: Achieved significant sensitivity enhancement by combining a non-modified BDD electrode with the cationic surfactant, Cetyltrimethylammonium bromide (CTAB).
- Performance Gain: The presence of 5·10-5 mol l-1 CTAB increased the DIF oxidation signal sensitivity by 6.8 times compared to CTAB-free measurements.
- Electrode Mechanism: The DIF oxidation was confirmed as an irreversible, diffusion-controlled process occurring at a highly positive potential (+1.07 V vs. Ag/AgCl).
- High Sensitivity: The optimized Square Wave Voltammetry (SWV) protocol yielded a low Limit of Detection (LOD) of 0.013 ”g ml-1 (5.2·10-8 mol l-1).
- Linear Range: Excellent linearity was established across the concentration range of 0.05 to 2.0 ”g ml-1 (2.0·10-7 to 8.0·10-6 mol l-1).
- Practical Application: The method was successfully validated for commercial pharmaceutical tablets, demonstrating high accuracy (average recovery 99.8%) and robustness against common excipients.
Technical Specifications
Section titled âTechnical Specificationsâ| Parameter | Value | Unit | Context |
|---|---|---|---|
| Working Electrode Material | Boron-Doped Diamond (BDD) | N/A | Non-modified, 3 mm diameter |
| Boron Doping Level | 1000 | ppm | BDD electrode specification |
| Supporting Electrolyte | 0.1 mol l-1 Phosphate Buffer Solution (PBS) | N/A | Optimized pH 2.5 |
| Cationic Surfactant (CTAB) Concentration | 5·10-5 | mol l-1 | Optimized for maximum enhancement |
| Oxidation Peak Potential (Ep) | +1.07 | V (vs. Ag/AgCl) | Optimized SWV measurement |
| Accumulation Time | 30 | s | Open-circuit potential, 500 rpm stirring |
| SWV Frequency (f) | 75 | Hz | Optimized instrumental setting |
| SWV Pulse Amplitude (ÎEsw) | 40 | mV | Optimized instrumental setting |
| Linear Working Range (Mass) | 0.05 to 2.0 | ”g ml-1 | DIF quantification |
| Limit of Detection (LOD) | 0.013 (5.2·10-8) | ”g ml-1 (mol l-1) | Calculated via 3s/m formula |
| Sensitivity Enhancement Factor | 6.8 | times | Signal increase with CTAB vs. without CTAB |
| Charge Transfer Coefficient (αn) | 0.87 (n â 2) | N/A | Determined from CV analysis |
| Tablet Recovery Rate | 99.8 | % | Average recovery for commercial samples |
Key Methodologies
Section titled âKey MethodologiesâThe quantitative analysis utilized Square Wave Adsorptive Stripping Voltammetry (SW-AdSV) on a BDD electrode following specific pretreatment and optimization steps:
- BDD Pretreatment Cycle: The electrode underwent sequential anodic (+1.8 V) and cathodic (-1.8 V) pretreatment steps, each lasting 180 s in 0.5 mol l-1 H2SO4, to ensure stable oxygen and hydrogen-terminated surface properties.
- Electrolyte Selection: A 0.1 mol l-1 Phosphate Buffer Solution (PBS) at pH 2.5 was selected as the optimal supporting electrolyte, providing the sharpest and most uniform DIF oxidation peak.
- Surfactant Optimization: The cationic surfactant CTAB was added to the electrolyte, with the optimal concentration determined to be 5·10-5 mol l-1 for maximum signal amplification.
- SWV Parameter Optimization: Instrumental parameters were tuned for maximum sensitivity and peak shape: frequency (f) at 75 Hz, pulse amplitude (ÎEsw) at 40 mV, and step potential (ÎEs) at 10 mV.
- Adsorption/Accumulation: A 30 s accumulation step was performed at open-circuit potential while the solution was stirred at 500 rpm, allowing DIF to adsorb onto the BDD surface, enhanced by the CTAB presence.
- Stripping Measurement: After a 5 s rest period, anodic scanning was performed from 0 V to +1.5 V, yielding the DIF oxidation peak at +1.07 V.
- Kinetic Confirmation: Cyclic Voltammetry (CV) confirmed the reaction was irreversible and diffusion-controlled, characterized by a linear relationship between the anodic peak current (Ipa) and the square root of the scan rate (v1/2).
Commercial Applications
Section titled âCommercial ApplicationsâThe developed methodology leverages the unique properties of BDD electrodes and surfactant chemistry, making it highly relevant for several industrial and analytical sectors:
- Pharmaceutical Quality Control (QC): Provides a rapid, low-cost, and highly sensitive alternative to traditional chromatographic methods (e.g., HPLC) for quantifying active pharmaceutical ingredients (APIs) like NSAIDs in tablet and capsule formulations.
- Electrochemical Sensor Development: Validates the use of non-modified BDD electrodes in combination with surfactants for enhancing the detection of organic molecules, serving as a reference for developing new electrochemical sensors.
- Environmental Analysis: Applicable for monitoring trace levels of pharmaceutical contaminants (PPCPs) in water and wastewater, utilizing the BDDâs stability and wide potential window for complex matrix analysis.
- BDD Electrode Technology: Confirms the high performance and reproducibility of BDD material (specifically 1000 ppm doping) in stripping voltammetry, supporting its adoption in advanced electroanalytical instrumentation.
- Clinical Drug Monitoring: The low Limit of Detection (LOD) suggests potential for future adaptation in therapeutic drug monitoring (TDM) to measure DIF concentrations in biological fluids, provided matrix effects are managed.
View Original Abstract
The present work describes a simple, fast, and inexpensive voltammetric method for diflunisal measurement using a non-modified boron-doped diamond (BDD) electrode. The oxidation of the agent was irreversible and presented a diffusionâcontrolled process. The sensitivity of the square wave voltammetric measurements were significantly improved when the cationic surfactant, cetyltrimethylammonium bromide (CTAB), was present in the supporting electrolyte solution. Using square-wave mode, a linear response was obtained for diflunisal quantification in 0.1 mol L-1 phosphate buffer solution (pH 2.5) solution containing 5Ă10-5 mol L-1 CTAB at +1.07 V (vs. Ag/AgCl) (after 30 s accumulation under open-circuit conditions). Linearity was found for 0.05 to 2.0 ÎŒg mL-1 (2.0Ă10-7-8.0Ă10-6 mol L-1) with a detection limit 0.013 ÎŒg mL-1 (5.2Ă10-8 mol L-1). The developed approach could be used for the quantification of diflunisal in pharmaceutical formulations.