An Interference-Free Voltammetric Method for the Detection of Sulfur Dioxide in Wine Based on a Boron-Doped Diamond Electrode and Reaction Electrochemistry

At a Glance

Metadata	Details
Publication Date	2023-08-17
Journal	International Journal of Molecular Sciences
Authors	Eva Culková, Zuzana Lukáčová-Chomisteková, Renata Bellová, Miroslav Rievaj, Jarmila Švancarová-Laštincová
Institutions	Catholic University in Ruzomberok
Citations	3
Analysis	Full AI Review Included

Technical Documentation & Analysis: Boron-Doped Diamond for Voltammetric SO₂ Detection in Wine

This document analyzes the research detailing an interference-free voltammetric method for sulfur dioxide (SO₂) detection in wine using a bare Boron-Doped Diamond (BDD) electrode. This application highlights the superior electrochemical stability and performance of MPCVD diamond materials supplied by 6CCVD.

Executive Summary

The following points summarize the technical achievements and core value proposition of using BDD for highly selective SO₂ analysis in complex matrices:

Application Validation: A simple, highly selective voltammetric method was successfully validated for determining free and total SO₂ content in complex white wine samples.
Material Selection: The method relies exclusively on an unmodified, bare Boron-Doped Diamond (BDD) electrode, leveraging diamond’s inherent low background current and resistance to fouling.
Mechanism: Detection is achieved via chemical redox cycling, where electrogenerated iodine (I₂) reacts with SO₂ (Bunsen reaction), and the resulting iodide (I^-) diffuses back to the electrode surface for reoxidation, significantly amplifying the signal.
High Sensitivity: The estimated detection limit (LOD) was achieved in the range of 10^-6-10^-7 mol dm^-3, allowing for high sample dilution and low chemical consumption.
Interference Control: Selectivity was ensured through optimized pH (0.1 mol dm^-3 HClO₄) and chemical pre-treatment steps (NaOH for total SO₂, formaldehyde/Chelaton III for interference blanking).
Commercial Viability: The technique is faster, requires less sample/reagent consumption, and is lower cost than traditional titrimetric or expensive optical methods, positioning BDD as a strong candidate for routine wine quality control.

Technical Specifications

The following hard data points were extracted from the experimental results and methodology:

Parameter	Value	Unit	Context
Electrode Material	Boron-Doped Diamond (BDD)	N/A	Unmodified, bare surface
Electrode Geometry	1.5	mm radius	Used in PEEK tube housing
Electrochemical Technique	Linear Sweep Voltammetry (LSV)	N/A	Used for quantification
Scan Rate	50	mV s^-1	Standard measurement speed
Optimal Supporting Electrolyte	0.1 mol dm^-3 HClO₄	Concentration	Optimized for maximal signal amplification (pH ≈ 1)
Optimal KI Concentration	2 x 10^-5	mol dm^-3	Initial concentration for redox cycling
Estimated Detection Limit (LOD)	10^-6-10^-7	mol dm^-3	Based on 3SA/B criterion
Calibration Linearity (R²)	0.994	N/A	Linearity for Na₂SO₃ concentration dependence
Operating Temperature	25.0 ± 0.5	°C	Controlled environment
Cleaning Potential	-3	V vs. Ag/AgCl	Chronoamperometric cleaning in 0.6 mol dm^-3 H₂SO₄

Key Methodologies

The experiment utilized a three-electrode voltammetric setup combined with specific chemical pre-treatment steps to isolate and quantify SO₂ species.

Electrode Pre-treatment: The BDD working electrode was cleaned chronoamperometrically in 0.6 mol dm^-3 H₂SO₄ at a constant potential of -3 V vs. Ag/AgCl for 300 s to ensure a clean, active surface.
Electrolyte Selection: 0.1 mol dm^-3 HClO₄ was selected as the optimal supporting electrolyte due to its highly acidic nature (pH ≈ 1), which maximized the signal amplification produced by the chemical redox cycling.
Anodic Generation: Iodine (I₂) was electrogenerated from iodide (I^-) on the BDD surface via anodic oxidation (2I^- - 2e^- → I₂).
Redox Cycling: The electrogenerated I₂ reacted rapidly with SO₂ in the diffusion layer (Bunsen reaction: SO₂ + I₂ + 2H₂O → H₂SO₄ + 2I^- + 2H⁺). The product, iodide (I^-), diffused back to the electrode surface and was reoxidized, closing the catalytic cycle and enhancing the current response.
Free SO₂ Determination: Direct LSV measurement was performed on the diluted wine sample (1 mL wine in 25 mL cell) after optimization.
Total SO₂ Determination: Samples were pre-treated with 4 mol dm^-3 NaOH for 5 minutes to release bonded SO₂ (e.g., HCHOSO₂) into the free form (Na₂SO₃) before measurement.
Interference Blanking: Formaldehyde and Chelaton III (EDTA) were used to bind free SO₂ and inactivate metal ions, respectively, allowing the measurement of interfering species that react with iodine, which was then subtracted as a blank.

6CCVD Solutions & Capabilities

This research successfully demonstrates the critical role of high-quality, bare BDD electrodes in developing advanced, routine analytical methods for complex food and beverage matrices. 6CCVD is uniquely positioned to supply the materials and customization required to replicate, scale, and advance this research.

Research Requirement	6CCVD Applicable Materials & Services	Value Proposition for the Researcher
High-Performance BDD Material	Boron-Doped Diamond (BDD) Wafers/Plates: We supply high-quality MPCVD BDD material optimized for electrochemical sensing, ensuring the wide potential window and low background current necessary for this redox cycling mechanism.	Guaranteed Electrochemical Purity: Access to BDD substrates with controlled doping levels for optimal conductivity and stability, crucial for achieving the reported 10^-6-10^-7 mol dm^-3 LOD.
Custom Electrode Dimensions	Precision Laser Cutting Services: The paper used a 1.5 mm radius electrode. 6CCVD provides custom laser cutting and shaping of BDD plates to exact specifications for integration into PEEK housings or specialized flow cells.	Seamless Integration: Receive BDD electrodes pre-cut to the required diameter or geometry, minimizing preparation time and maximizing experimental repeatability.
Need for Stable, Clean Surface	Ultra-Smooth Polishing (Ra < 1 nm): Our Single Crystal Diamond (SCD) polishing achieves surface roughness (Ra) < 1 nm, and our inch-size Polycrystalline Diamond (PCD) polishing achieves Ra < 5 nm.	Reduced Fouling and Adsorption: A superior surface finish minimizes matrix adsorption (a known challenge in wine analysis) and ensures long-term sensor stability and accuracy.
Scaling and Advanced Sensor Design	Large-Area PCD Substrates (up to 125 mm): For scaling up production or developing microfabricated sensors (e.g., interdigitated arrays mentioned in the references), we offer PCD wafers up to 125 mm in diameter.	Platform for Commercialization: Enables the transition from laboratory-scale disc electrodes to high-throughput, integrated sensor arrays for industrial wine control applications.
Electrode Contacting/Packaging	Custom Metalization Services: We offer in-house deposition of metals (Au, Pt, Ti, W, Cu) for creating robust electrical contacts or defining specific active areas on the diamond surface.	Ready-to-Use Components: Supply BDD materials with pre-applied metal contacts, simplifying packaging and ensuring reliable connection to potentiostats.

Engineering Support

6CCVD’s in-house PhD team specializes in diamond material science and electrochemical applications. We can assist researchers and engineers in selecting the optimal BDD doping concentration, surface termination, and geometry required to replicate or extend this highly sensitive voltammetric detection platform for similar food safety and quality control projects.

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

View Original Abstract

This paper describes a new, simple, and highly selective analytical technique for the detection of sulfur dioxide in wine, as a real sample with a relatively complicated matrix. The detection of the above analyte was based on the electrogeneration of iodine from iodide on a boron-doped diamond electrode, without modifications, in the presence of 0.1 mol dm−3 HClO4 as a supporting electrolyte. The electrogenerated iodine reacted with sulfur dioxide, forming iodide ions and sulfuric acid (i.e., a Bunsen reaction). The product of this reaction, the iodide ion, diffused back to the surface of the boron-doped diamond electrode and oxidized itself again. This chemical redox cycling enhanced the voltammetric response of the boron-doped diamond electrode. The selectivity of the determination was assured using NaOH and formaldehyde during sample preparation, and a blank was also measured and taken into account. The detection limit was estimated to be 10−6-10−7 mol dm−3. However, the content of sulfur dioxide in wine is significantly higher, which can lead to more accurate and reliable results.

Tech Support

Original Source

DOI: https://doi.org/10.3390/ijms241612875

References

2016 - Food Safety Risk Assessment for Estimating Dietary Intake of Sulfites in the Taiwanese Population [Crossref]
2013 - Determination of Sulfites in Wine
2015 - A Headspace Gas Detection Tube Method to Measure SO2 in Wine without Disruption SO2 Equilibria [Crossref]
2013 - Determination of Sulfur Dioxide in Wine Using Headspace Gas Chromatography and Electron Capture Detection [Crossref]
2015 - Headspace Thin-Film Microextraction Coupled with Surface-Enhanced Raman Scattering as a Facile Method for Reproducible and Specific Detection of Sulfur Dioxide in Wine [Crossref]
2020 - Direct Quantification of Sulfur Dioxide in Wine by Surface Enhanced Raman Spectroscopy [Crossref]
2021 - The Effects of Sulphur Dioxide on Wine Metabolites: New Insights from H-1 NMR Spectroscopy Based In-Situ Screening, Detection, Identification and Quantification [Crossref]
2021 - Microanalytical Flow System for the Simultaneous Determination of Acetic Acid and Free Sulfur Dioxide in Wines [Crossref]