Voltammetric measurement of catechol-O-methyltransferase inhibitor tolcapone in the pharmaceutical form on the boron-doped diamond electrode

At a Glance

Metadata	Details
Publication Date	2024-02-21
Journal	TURKISH JOURNAL OF CHEMISTRY
Authors	Musa Kıran, Yavuz Yardım
Institutions	Czech Academy of Sciences, Institute of Analytical Chemistry
Citations	3
Analysis	Full AI Review Included

Technical Analysis: Voltammetric Measurement of Tolcapone on Boron-Doped Diamond (BDD) Electrodes

This document analyzes the research detailing the use of Boron-Doped Diamond (BDD) electrodes for the sensitive and selective voltammetric measurement of Tolcapone (TOL), a critical pharmaceutical agent. This application highlights the superior electrochemical properties of 6CCVD’s MPCVD BDD materials for advanced analytical chemistry and sensor development.

Executive Summary

Core Value Proposition: A rapid, cost-effective, and simple electroanalytical method was successfully developed for the quantification of Tolcapone (TOL) in commercial pharmaceutical formulations using a Boron-Doped Diamond (BDD) electrode.
Material Performance: The BDD electrode demonstrated excellent chemical stability, low fouling characteristics, and high selectivity, crucial for reliable analysis in complex matrices containing fillers and interfering ions.
Optimal Methodology: Square Wave Voltammetry (SWV) combined with Cathodic Pretreatment (CPT) yielded the highest sensitivity, achieving an optimal anodic peak potential (E_p) of +0.66 V (vs. Ag/AgCl) in 0.1 M PBS (pH 2.5).
High Sensitivity Achieved: The method established a wide linear working range (LWR) of 1.0-50.0 µg mL⁻¹ and a low Limit of Detection (LOD) of 0.29 µg mL⁻¹ (1.1 x 10⁻⁶ M).
Real-World Application: The developed CPT-BDD platform was successfully validated by measuring TOL in commercial tablets, yielding high recovery rates (103.2% to 106.2%), confirming its practical applicability.
Future Potential: The findings support the use of BDD electrodes in future electroanalytical investigations, including high-speed amperometric sensing for pharmaceutical and biological fluid analysis.

Technical Specifications

The following hard data points were extracted from the optimal SWV analysis of Tolcapone (TOL) on the CPT-BDD electrode:

Parameter	Value	Unit	Context
Electrode Material	Boron-Doped Diamond (BDD)	N/A	MPCVD material
Boron Doping Concentration	1000	ppm	Used for the 3 mm diameter electrode
Optimal Peak Potential (E_p)	+0.66	V	Anodic peak potential (vs. Ag/AgCl)
Optimal Supporting Electrolyte	0.1 mol L⁻¹ PBS	N/A	Phosphate Buffer Solution at pH 2.5
Linear Working Range (LWR)	1.0-50.0	µg mL⁻¹	Equivalent to 3.7 x 10⁻⁶ - 1.8 x 10⁻⁴ M
Limit of Detection (LOD)	0.29	µg mL⁻¹	High sensitivity achieved by SWV
Correlation Coefficient (r)	0.9984	N/A	Demonstrates excellent linearity
Intra-day Repeatability (RSD%)	5.8	%	Measured at 1.0 µg mL⁻¹ TOL (n=10)
Inter-day Repeatability (RSD%)	7.1	%	Measured over three consecutive days (n=3)
Optimal SWV Frequency (f)	100	Hz	Optimized Square Wave Voltammetry setting
Optimal SWV Pulse Amplitude (ΔE_SW)	60	mV	Optimized Square Wave Voltammetry setting

Key Methodologies

The successful quantification of TOL relied on precise control over the BDD electrode surface and optimized voltammetric parameters:

Electrode Material Selection: A Boron-Doped Diamond (BDD) electrode (3 mm diameter, 1000 ppm B) was chosen for its wide potential window and low adsorption characteristics, minimizing fouling.
Cathodic Pretreatment (CPT) Optimization: CPT was identified as the most effective pretreatment method, significantly enhancing sensitivity compared to anodic or combined pretreatment.
- Initial Cleaning: -1.8 V applied for 180 s in 0.5 mol L⁻¹ H₂SO₄.
- Routine Cleaning: -1.8 V applied for 60 s in 0.5 mol L⁻¹ H₂SO₄ before each measurement to ensure a clean surface and prevent adsorption of TOL oxidation products.
Electrolyte and pH Selection: The oxidation of TOL was found to be highly pH-dependent. Optimal performance was achieved using 0.1 mol L⁻¹ Phosphate Buffer Solution (PBS) at pH 2.5.
Voltammetric Technique Selection: Square Wave Voltammetry (SWV) was selected over Cyclic Voltammetry (CV) and Differential Pulse Voltammetry (DPV) due to its superior sensitivity and rapid analysis rate.
Analytical Validation: The method was validated using the standard addition method to measure TOL in commercial tablet samples, demonstrating high recovery and minimal matrix interference from common pharmaceutical fillers.

6CCVD Solutions & Capabilities

This research validates the critical role of high-quality, customized Boron-Doped Diamond (BDD) electrodes in advanced electroanalytical chemistry. 6CCVD is uniquely positioned to supply the materials and engineering support required to replicate, scale, and extend this research into commercial sensor platforms.

Research Requirement	6CCVD Solution & Capability	Value Proposition for Researchers/Engineers
Applicable Materials	Heavy Boron-Doped PCD/SCD Wafers. We provide MPCVD BDD with precise, tunable doping levels (e.g., replicating the 1000 ppm used here) for high conductivity and wide electrochemical windows.	Guaranteed Consistency: Access to high-purity, highly reproducible BDD material essential for reliable LOD/LOQ metrics and long-term sensor stability.
Electrode Dimensions (3 mm disc)	Custom Laser Cutting & Sizing. We supply PCD plates up to 125 mm and offer precision laser cutting to produce custom electrode geometries (e.g., 3 mm discs, micro-arrays, or flow cell inserts).	Scalability & Prototyping: Rapid transition from small R&D electrodes to large-scale, custom-sized sensor arrays without compromising material quality.
Surface Quality & Repeatability	Ultra-Low Roughness Polishing (Ra < 5 nm). Our advanced polishing techniques for PCD minimize surface defects and roughness, reducing adsorption and fouling.	Enhanced Lifetime & Signal Integrity: Reduces the need for aggressive or frequent pretreatment cycles (like CPT), extending electrode lifetime and improving signal repeatability (RSD < 7.1%).
Integration & Sensor Development	Custom Metalization Services. For integrating BDD into commercial sensors, 6CCVD offers in-house deposition of metals (Au, Pt, Pd, Ti, W, Cu) for robust electrical contacts and bonding.	Turnkey Manufacturing: Provides ready-to-integrate BDD components, streamlining the development of complex amperometric or voltammetric sensor devices.
Engineering Support	In-House PhD Team Consultation. Our experts specialize in optimizing BDD material selection (doping concentration, PCD vs. SCD) and surface termination for specific electroanalytical applications, such as pharmaceutical and biological fluid sensing.	Accelerated R&D: Leverage our deep expertise to quickly optimize material parameters for similar Tolcapone (TOL) sensing or other neurodegenerative drug analysis projects.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

This study presents an electroanalytical approach to measure the catechol-O-methyltransferase (COMT) inhibitor tolcapone (TOL) using a boron-doped diamond (BDD) electrode. The application of cyclic voltammetry (CV) technique revealed that TOL exhibited a distinct, diffusion-controlled, irreversible anodic peak at a potential of approximately +0.71 V (vs. Ag/AgCl) in a 0.1 mol L-1 phosphate buffer solution (PBS) with a pH of 2.5. The oxidation of TOL is highly dependent on the pH and supporting electrolytes. Based on the data obtained from the pH investigation, a proposed mechanism for the electro-oxidation of TOL is suggested. Using the square wave voltammetry (SWV) technique, a satisfactory linear relationship was observed at approximately +0.66 V in a 0.1 mol L-1 PBS with a pH of 2.5. The presented method exhibited linearity within the concentration range between 1.0-50.0 μg mL-1 (3.7 × 10-6-1.8 × 10-4 mol L-1), with a limit of detection (LOD) of 0.29 μg mL-1 (1.1 × 10-6 mol L-1). The BDD electrode demonstrated good selectivity against inorganic ions and filler materials interference. Finally, the suitability of the developed approach was assessed by measuring TOL in tablet formulations, resulting in favorable recoveries ranging from 103.4% to 106.2%.

Tech Support

Original Source

DOI: https://doi.org/10.55730/1300-0527.3650