Simultaneous Voltammetric/Amperometric Determination of Sulfide and Nitrite in Water at BDD Electrode

At a Glance

Metadata	Details
Publication Date	2015-06-19
Journal	Sensors
Authors	Anamaria Baciu, Magdalena Ardelean, Aniela Pop, Rodica Pode, Florica Manea
Institutions	Polytechnic University of Timişoara
Citations	35
Analysis	Full AI Review Included

Technical Analysis of Boron-Doped Diamond Electrodes for Simultaneous Anion Detection

Reference: Baciu et al. Simultaneous Voltammetric/Amperometric Determination of Sulfide and Nitrite in Water at BDD Electrode. Sensors 2015, 15, 14526-14538.

Executive Summary

This study successfully established high-performance electrochemical protocols for the simultaneous, interference-free detection of sulfide (S^2-) and nitrite (NO₂^-) anions in water, leveraging the exceptional properties of Boron-Doped Diamond (BDD) electrodes.

Core Achievement: Simultaneous and sensitive determination of S^2- and NO₂^-, critical water pollutants, using advanced pulse electrochemical techniques.
Material Validation: Confirmed BDD’s suitability for electroanalysis due to its large potential window and inherently low background current, crucial for trace analysis.
Optimal Voltammetry: Square-Wave Voltammetry (SWV) under optimized conditions yielded the best sensitivity (396.0 µA/mM for S^2-) and lowest Limit of Detection (LOD) (1.16 x 10^-5 mM).
In-Field Protocol: Multiple-Pulsed Amperometry (MPA) was developed as a robust, field-ready protocol using a three-level pulse scheme to successfully eliminate the interference between the two anions.
Interference Mitigation: The MPA protocol utilized precise potential steps and timing ratios (3.0 s oxidation time for S^2- vs. 0.3 s for NO₂^-) to ensure quantitative, non-cumulative signal recording.
Practical Accuracy: The optimized MPA technique demonstrated high accuracy in tap water analysis (94% recovery for S^2- and 96% for NO₂^-), validating its potential for practical environmental monitoring.

Technical Specifications

Extraction of key performance metrics and hardware specifications from the research.

Parameter	Value	Unit	Context
Electrode Type	BDD Disc (Commercial)	N/A	Working Electrode Material
Electrode Diameter	3.0	mm	Physical Dimension
Boron Doping Degree	~0.1	%	Material Specification
Supporting Electrolyte	0.1 M Na₂SO₄	Concentration/Chemical	Standardized conditions
Reference Electrode	Saturated Calomel Electrode (SCE)	N/A	Reference Potential
Optimized SWV Amplitude	0.5	V	Best Sensitivity and LOD
Optimized SWV Frequency	10	Hz	Best Analytical Performance
Best S^2- Sensitivity (SWV)	396.0	µA/mM	Achieved using 0.5 V modulation amplitude
Best NO₂^- Sensitivity (SWV)	300.0	µA/mM	Achieved using 0.5 V modulation amplitude
Lowest S^2- LOD (SWV)	1.16 x 10^-5	mM	Key performance indicator
Sulfide Oxidation Potential (MPA)	+0.85	V/SCE	E₂ potential level for selective S^2- detection
Nitrite Oxidation Potential (MPA)	+1.25	V/SCE	E₃ potential level for selective NO₂^- detection
Sulfide Oxidation Time (MPA)	3.0	s	Optimized duration to ensure full oxidation
Nitrite Oxidation Time (MPA)	0.3	s	Optimized duration for quick, selective oxidation

Key Methodologies

The core of the successful simultaneous detection hinged upon the precise control of the electrochemical system, particularly through BDD pre-treatment and tailored MPA pulse sequencing.

1. Electrochemical Setup and Material Pre-Treatment

Cell Configuration: Standard three-electrode system employed: BDD working electrode, Platinum (Pt) counter electrode, and Saturated Calomel Electrode (SCE) reference electrode.
Electrochemical Pre-Treatment: Prior to each experiment, the BDD electrode underwent three repetitive potential cycles in the supporting electrolyte (0.1 M Na₂SO₄) between -0.5 V and +1.25 V vs. SCE.

2. Optimized Square-Wave Voltammetry (SWV)

Purpose: To achieve maximum electroanalytical sensitivity and lowest LOD.
Conditions: Step Potential: 0.01 V; Modulation Amplitude: 0.5 V; Frequency: 10 Hz.

3. Optimized Multiple-Pulsed Amperometry (MPA) for In-Field Use

Principle: Three sequential potential steps are applied continuously to achieve conditioning, selective S^2- oxidation, and selective NO₂^- oxidation (which also functions as an electrode cleaning step).
Pulse Scheme (E₁, E₂, E₃):
1. Conditioning Step (E₁): -0.5 V/SCE for a duration of 0.3 s.
2. Sulfide Detection Step (E₂): +0.85 V/SCE for a duration of 3.0 s (Ensuring full S^2- oxidation).
3. Nitrite Detection/Cleaning Step (E₃): +1.25 V/SCE for a duration of 0.3 s (Ensuring NO₂^- oxidation and electrode surface renewal).
Interference Control: The critical 10:1 ratio (3.0 s vs. 0.3 s) between the S^2- oxidation time and the NO₂^- oxidation/cleaning time was necessary to prevent sulfide oxidation products from interfering with the nitrite measurement.

6CCVD Solutions & Capabilities

6CCVD provides the specialized MPCVD Boron-Doped Diamond required to replicate, scale, and advance the protocols described in this paper for environmental or industrial sensing applications.

Applicable Materials: Custom Boron-Doped Diamond (BDD)

The research successfully utilized BDD with 0.1% boron doping. 6CCVD’s superior MPCVD synthesis capability ensures the precise and repeatable production of highly conductive BDD electrodes, exceeding commercial standards.

Material	Key Specification	Application Alignment
Heavy Boron Doped PCD (Polycrystalline Diamond)	Customizable doping levels (e.g., matching or exceeding 0.1% B/C ratio) to ensure high conductivity and large electrochemical window.	Direct replacement for the commercial electrode used, guaranteeing low background current and high sensitivity for low-LOD applications (SWV).
Thick BDD Substrates	Available up to 10 mm thick, or thin films from 0.1 µm.	Ideal for robustness in high-volume industrial flow cells or integration into complex sensor arrays for high-pressure/corrosive environments.

Customization Potential for Advanced Sensing

The move toward Multiple-Pulsed Amperometry (MPA) suggests a strong commercial interest in creating small, portable, and integrated in-field sensors. 6CCVD’s advanced processing capabilities directly facilitate this transition.

Microelectrode and Array Fabrication: The paper used a 3 mm disc, but modern portable sensors require miniaturization. 6CCVD offers precision laser cutting services to transform large BDD wafers (up to 125 mm) into custom-shaped microelectrodes, interdigitated arrays, or integrated three-electrode systems required for compact systems.
On-Chip Metalization and Integration: The three-electrode system (BDD working, Pt counter, SCE reference) is cumbersome for field use. 6CCVD offers in-house custom metalization (Au, Pt, Ti, Pd), allowing researchers to pattern BDD working electrodes directly alongside integrated Pt or Au counter/quasi-reference electrodes onto a single diamond substrate, drastically simplifying system architecture.
Ultra-Low Current Performance: To push the limits of detection (LOD) lower than the 10^-5 mM achieved by SWV, minimizing background current is vital. 6CCVD provides ultra-smooth polishing (Ra < 5nm for inch-size PCD/BDD), ensuring minimal surface defects and maximized repeatability for enhanced electroanalytical performance.

Engineering Support & Global Supply Chain

6CCVD understands the need for consistency and collaboration in frontier research.

Engineering Consultation: 6CCVD’s in-house PhD team provides specialized engineering support for projects targeting environmental sensing, water quality monitoring, and in-field electrochemical analysis. We assist researchers and engineers in selecting the optimal BDD thickness, doping level, and surface finish (e.g., polished vs. as-grown) to maximize performance for specific redox reactions.
Reliable Global Supply: We offer global shipping (DDU default, DDP available) to ensure rapid and secure delivery of custom-fabricated BDD materials worldwide, supporting timely development of commercial sensing platforms.

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

View Original Abstract

This work reported new voltammetric/amperometric-based protocols using a commercial boron-doped diamond (BDD) electrode for simple and fast simultaneous detection of sulfide and nitrite from water. Square-wave voltammetry operated under the optimized working conditions of 0.01 V step potential, 0.5 V modulation amplitude and 10 Hz frequency allowed achieving the best electroanalytical parameters for the simultaneous detection of nitrite and sulfide. For practical in-field detection applications, the multiple-pulsed amperometry technique was operated under optimized conditions, i.e., −0.5 V/SCE for a duration of 0.3 s as conditioning step, +0.85 V/SCE for a duration of 3 s that assure the sulfide oxidation and +1.25 V/SCE for a duration of 0.3 s, where the nitrite oxidation occurred, which allowed the simultaneously detection of sulfide and nitrite without interference between them. Good accuracy was found for this protocol in comparison with standardized methods for each anion. Also, no interference effect was found for the cation and anion species, which are common in the water matrix.

Tech Support

Original Source

DOI: https://doi.org/10.3390/s150614526

References

2014 - Heterotrophic and Elemental-Sulfur-Based Autotrophic Denitrification Processes for Simultaneous Nitrate and Cr (VI) Reduction [Crossref]
2015 - Electrochemical and Other Methods for Detection and Determination of Dissoleved Nitrite: A Review [Crossref]
2010 - Simultaneous Electrochemical Determination of Nitrate and Nitrite in Aqueous Solution Using Ag-doped Zeolite-Expanded Graphite-Epoxy Electrode [Crossref]
1997 - The Determination of Sulfide in Seawater by Flow-Analysis with Voltammetric Detection [Crossref]
1999 - Metal-Sulfide Complexation in Seawater [Crossref]
2009 - Sulfide Removal by Simultaneous Autotrophic and Heterotrophic Desulfurization-Denitrification Process [Crossref]
2012 - Simultaneous Sulfide and Nitrite Removal from Industrial Wastewaters under Denitrifying Conditions [Crossref]
1995 - Hydrogen Sulfide and Reduced-Sulfur Gases Adversely Affect Neurophysiological Functions [Crossref]
2002 - Determination of Nitrate and Nitrite by High-Performance Liquid Chromatography in Human Plasma [Crossref]