Amperometric Determination of Hydrogen Peroxide in Whitening Gels Using Boron-doped Diamond Electrode

At a Glance

Metadata	Details
Publication Date	2018-05-18
Journal	Analytical Sciences
Authors	Gustavo Chevitarese Azevedo, Roberto H. S. Castro, Maria Auxiliadora Costa Matos, Renato Camargo Matos
Institutions	Universidade Federal de Juiz de Fora
Citations	8
Analysis	Full AI Review Included

BDD Diamond for High-Sensitivity Amperometry: Analysis of Hydrogen Peroxide Determination

6CCVD Technical Document Reference: BDD-H₂O₂-FIA-2018

Executive Summary

This study successfully demonstrates the superior performance of Boron-Doped Diamond (BDD) electrodes manufactured via MPCVD when applied to highly sensitive electroanalysis using Flow Injection Analysis (FIA). The core findings establish BDD as the ideal material for rapid, high-throughput, and precise determination of hydrogen peroxide (H₂O₂) in complex matrices, such as commercial whitening gels.

Material Superiority: BDD electrodes exhibited significantly higher sensitivity (current density) for H₂O₂ oxidation (0.23 mA cm^-2) compared to traditional noble metals and carbon electrodes (Au: 0.07 mA cm^-2; Pt: 0.13 mA cm^-2; Glassy Carbon: negligible signal).
Activation Efficacy: A simple, repeatable cathodic activation protocol (-2.9 V for 340 s) ensured high reproducibility and conferred maximum sensitivity without requiring complex surface modification (e.g., metal or enzyme immobilization).
High Throughput: The FIA system coupled with the BDD electrode achieved a high analytical frequency of 63 injections per hour, enabling rapid quality control and sample screening.
Precision and Accuracy: The method yielded excellent precision, demonstrated by a low Relative Standard Deviation (RSD) of 1.1% in repeatability tests and recovery values ranging from 74% to 107%.
Low Detection Limits: Detection and quantification limits were established at 1.06 µmol L^-1 and 3.54 µmol L^-1, respectively, highlighting the BDD electrode’s ability to detect trace concentrations.
Engineering Benefit: The BDD’s inherent resistance to fouling and the non-enzyme-dependent reaction mechanism (H₂O₂ to H₂O) significantly reduced long-term maintenance and analytical costs compared to biosensor-based methods.

Technical Specifications

Parameter	Value	Unit	Context
Electrode Material	Boron-Doped Diamond (BDD)	-	Concentration: 6000-8000 ppm
Electrode Type	Working Electrode (WE)	-	Fixed to copper plate adapter
Applied Potential	+0.60	V	vs. Ag/AgCl_(sat)
Optimum Flow Rate (Electrolyte)	2.80	mL min^-1	Phosphate Buffer Solution (PBS)
Optimum Sample Volume	175	µL	Equivalent to 28.5 cm sample loop
Electrode Exposed Area	0.28	cm²	Defined by rubber O-ring in PTFE cell
H₂O₂ Detection Limit (DL)	1.06	µmol L^-1	Calculated via 3S method
H₂O₂ Quantification Limit (QL)	3.54	µmol L^-1	Calculated via 10S method
Analytical Frequency	63	Injections per hour	High-throughput FIA capability
Sensitivity (BDD Current Density)	0.23	mA cm^-2	Superior to Pt (0.13 mA cm^-2) and Au (0.07 mA cm^-2)
System Precision (RSD)	1.1	%	10 consecutive injections of 19.5 µmol L^-1 H₂O₂
Electrolyte (Supporting)	PBS 0.1 mol L^-1	pH 7.00	Optimized for stability and response

Key Methodologies

The determination relied on coupling a custom-designed electrochemical flow cell with Flow Injection Analysis (FIA) using an activated BDD working electrode.

BDD Electrode Activation & Cleaning Protocol

The BDD electrode required specific pre-treatment to ensure stable and highly sensitive measurements:

Cathodic Activation (Daily):
- Potential: -2.9 V.
- Duration: 340 s.
- Electrolyte: 3 mol L^-1 H₂SO₄.
Anodic Cleaning (Weekly or PRN):
- Current: 0.1 A.
- Duration: 2000 s.
- Purpose: To restore sensitivity and remove accumulated residues.
Post-Cleaning Treatment: Immediately followed by the standard cathodic activation protocol.

Electrochemical Flow Cell Design

The methodology utilized a miniaturized, lab-made PTFE (Polytetrafluoroethylene) flow cell designed specifically for integration with the BDD plate.

Internal Volume: Up to 100 µL.
Electrode Attachment: BDD plate fixed to a copper adapter using screws to establish electrical contact.
O-Ring Function: A rubber O-ring was essential to limit the exposed active area of the BDD film to 0.28 cm².
Electrode Configuration: Three-electrode system consisting of the BDD Working Electrode (WE), a miniaturized Ag/AgCl_(sat) Reference Electrode (RE), and a Platinum needle Counter Electrode (CE).

Optimized FIA Parameters

The high efficiency was achieved by tuning the flow system parameters:

Carrier Solution: Phosphate Buffer Solution (PBS) at 0.1 mol L^-1 (pH 7.00).
Flow Optimization: Flow rate maximized to 2.80 mL min^-1 to reduce dispersion and maintain signal height.
Injection Volume: Fixed at 175 µL, selected to maximize signal without unnecessarily widening the peak signal.
Signal Measurement: Amperometric detection at the fixed potential of +0.60 V.

6CCVD Solutions & Capabilities

This research validates BDD diamond as the preferred material platform for high-performance electroanalytical applications, particularly for sensors requiring robustness, high sensitivity, and chemical inertness. 6CCVD is uniquely positioned to supply the exact materials and custom fabrication required to replicate and advance this sensor technology.

Applicable Materials & Customization

Requirement from Paper	6CCVD Custom Solution	Technical Advantage
BDD Film (6000-8000 ppm)	Heavy Boron-Doped Diamond (BDD) Wafers	Guaranteed, precise control over Boron concentration (ppm) and uniformity for optimized electroactivity (critical for achieving 0.23 mA cm^-2 sensitivity).
Custom Electrode Area (0.28 cm²)	Precision Laser Cutting and Shaping	We fabricate custom shapes and dimensions from wafers up to 125mm, ensuring perfect integration into bespoke flow cells (PTFE or PEEK chambers).
Electrode Integration (Copper Contact)	Custom Metalization Layering	6CCVD offers in-house deposition of adhesion and contact layers (e.g., Ti/W/Au or Ti/Pt) directly onto the diamond film for reliable, low-resistance ohmic contact with external circuitry (e.g., copper adapter).
Polishing Requirements	Engineering Polish (Ra < 5nm)	While electrochemical sensors benefit from surface termination, 6CCVD ensures ultra-low roughness polishing for uniform film quality and clean interfacing with O-rings/flow structures.
Future Modifications	SCD Substrates up to 500 µm	For high-power or high-frequency electrochemistry requiring superior thermal management or extreme purity, we offer single crystal diamond (SCD) platforms for precise BDD layer growth.

Engineering Support

The successful fabrication of the miniaturized flow cell (Fig. 1) and the optimization of the cathodic activation procedure require specialized materials knowledge.

Application Replication: 6CCVD’s in-house PhD team provides consultative support on material selection, surface termination effects, and integration techniques necessary to replicate or optimize Flow Injection Analysis (FIA) and Amperometric Detection projects.
Sensor Development: We assist engineers in optimizing BDD doping profiles (tailored ppm B concentrations) for target analytes and selecting appropriate metalization schemes for robust chemical stability in harsh environments (e.g., concentrated H₂SO₄).
Global Logistics: Utilizing DDP shipping options, 6CCVD ensures the timely, secure, and compliant delivery of sensitive MPCVD materials globally, supporting rapid international research timelines.

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

Tech Support

Original Source

DOI: https://doi.org/10.2116/analsci.17p491