Voltammetry is a popular electrochemical technique used for food analysis owing to its high sensitivity, usability in varied temperatures and concentrations, and rapid processing time.1
This article discusses varied voltammetry techniques, such as cyclic voltammetry (CV), pulse voltammetry (PV), linear sweep voltammetry (LSV), and stripping voltammetry (SV), designed to ensure food quality and safety.
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The Principle and Working of Voltammetry in Food Analysis
Voltammetry is an analytical method first introduced in the 1920s by Jaroslav Heyrovský through his experiment that measured the surface tension of mercury and elucidated the nature of the liquid–metal interface.2
This technique provides information on the analytes based on their electrical current as a function of the potential applied to a working electrode.
The voltammetric process is carried out in an electrochemical cell comprising a working electrode, a reference electrode, and a counter electrode.3 The working electrode provides the interphase through which a charge could be transferred, or its effect felt.
It is essential to develop a working electrode with known dimensions and surface characteristics. The primary attributes of auxiliary electrodes are that they should not react with bulk analytes and be a good conductor of electricity.
The reference electrodes must be constant over time, provide a reversible half-reaction with Nernstian behavior, and be easy to assemble and maintain.
For aqueous solutions, the most commonly used reference electrodes are the silver/silver chloride electrode and the calomel electrode.4
Analytical chemistry routinely uses various voltammetry methods to determine the quantity of various dissolved organic and inorganic substances.5
The key advantages of these techniques are superior sensitivity over wide-ranging linear concentrations of both inorganic and organic analytes.
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Different Voltammetry Methods Used to Analyze Food
Over the years, voltammetry has been expanded to LSV, CV, PV, and SV.6 Some of the common types of voltammetry techniques used in food analysis are discussed below:
Cyclic voltammetry (CV)
CV measures the current in an electrochemical cell when the voltage exceeds the current predicted by the Nernst equation. A cyclic voltammogram is developed by plotting the current at the working electrode against the applied voltage.7
Pulse voltammetry (PV)
PV is used to utilize a frequently increasing pulse height that is applied at periodic intervals. This method detects, characterizes, and quantifies substances like polyphenols in wine products.6
Linear sweep voltammetry (LSV):
In LSV, the current at the working electrode is measured while the potential between the working and reference electrodes is swept linearly with time.
For food analysis, this method is used to estimate the potential at which oxidation or reduction of the analyte occurs at the working electrode, which is shown as a peak or trough in the current.8
Stripping voltammetry (SV):
SV entails pre-concentration of an analyte on an electrode, followed by a potential sweep to oxidize or reduce the analyte selectively. Here, the current generated is proportional to the total analyte present on the electrode.
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Importance of Electrode Materials in Food Assessment
It must be noted that the efficiency of the assessment is dependent on the type of electrode used in voltammetry. An electrode can be made up of alloys, nanomaterials, polymers, ceramic oxides, and surfactants.9
Recent studies have shown that working electrodes made from carbon-based materials, such as ordered mesoporous carbon (OMC), carbon dots (CD), boron-doped diamond (BDD), graphene, and carbon nanotubes (CNTs), are most efficient and suitable for food analysis.
This could be because these materials have a high activation energy barrier, large surface area, macroscopic quantum tunnelling effects, refined structure, and stability at room temperature.
The efficiency of an electrode in assessing food quality is significantly influenced by the morphology (e.g., rod, spherical, needle, and barrel) and size of carbon materials used for the electrode.
Each shape and size is associated with distinct chemical and electronic properties useful to detect specific analytes.
Applications of Voltammetry in Food Analysis
Chemical contaminants in foods are of greatest concern for regulatory authorities, food manufacturers, and consumers. Food quality and safety are assessed based on contamination (e.g., pesticides and additives) and pollutants.
It is important to assess food components because of their direct association with health outcomes.10
To attract consumers, synthetic colors, preservatives, and flavors are often added, which could influence food safety. Due to high sensitivity, accuracy, stability, and robustness, voltammetric methods detect toxic chemicals in food.
CV is the most commonly used method to assess food quality among the different types of volumetric techniques.
The main advantages of CV in food analysis are its ability to detect various analytes at low concentrations, its cost-effective approach, and its one-step detecting process.
Over the years, SV has been used to determine the presence of trace and ultra-trace concentrations of toxic metals, such as mercury, lead, cadmium, antimony, arsenic, and uranium in foods.
Differential pulse anodic stripping voltammetry has been used to detect cadmium and lead in agriculture crops simultaneously. This method detected toxic metals in beans, fish, apple juice, infant formula, and cereal. SV method exhibited high efficacy in detecting pesticide molecules in soil, foods, and tap water.
Residual veterinary drugs used to treat animals for bacterial/parasitic infections could enter the human diet through milk, meat, and dairy products.
The linear sweep stripping voltammetry (LSSV) method detected food products' antibiotics, such as nitroxyl and fluoroquinolones. The anodic stripping voltammetric method detected nitrite in sausages and pickled vegetables.
Voltammetric methods were also used to detect artificial colorants, such as tartrazine, ponceau 4R, and sunset yellow, in drinks, candy, and juice.
Conclusion
Voltammetry is a highly effective electrochemical technique for food analysis due to its sensitivity, versatility, and rapid processing. This article reviewed various voltammetry methods, including cyclic voltammetry (CV), pulse voltammetry (PV), linear sweep voltammetry (LSV), and stripping voltammetry (SV), highlighting their roles in ensuring food quality and safety.
Based on principles introduced by Jaroslav Heyrovský, the method relies on precise electrode selection and maintenance, with carbon-based materials offering significant advantages. Voltammetry is particularly useful in detecting chemical contaminants, toxic metals, and artificial colorants in food, providing a reliable means of ensuring food safety.
In summary, voltammetry's sensitivity, accuracy, and adaptability make it an essential tool in modern food analysis, effectively safeguarding consumer health by ensuring food products meet stringent safety standards.
References
- Buenaventura TMA, et al. The Role of Voltammetric Analysis in the Wine Industry. Engineering Proceedings. 2023; 56(1):152. https://doi.org/10.3390/ASEC2023-16641
- Singh R, et al. A Review on Recent Trends and Future Developments in Electrochemical Sensing. ACS Omega. 2024;9(7):7336-7356. doi: 10.1021/acsomega.3c08060.
- Bilal S. Cyclic Voltammetry. In: Kreysa, G., Ota, Ki., Savinell, R.F. (eds) Encyclopedia of Applied Electrochemistry. 2014; https://doi.org/10.1007/978-1-4419-6996-5_220
- Elgrishi N, et al. A Practical Beginner’s Guide to Cyclic Voltammetry. J Chem Edu. 2018; 95 (2), 197-206. DOI: 10.1021/acs.jchemed.7b00361
- Kolesnichenko I. Development of a Method for Multisensory Stripping Voltammetry in the Analysis of Medical Preparations. ACS Omega. 2023;8(43):40229-40241. doi: 10.1021/acsomega.3c03946.
- Alyamni N, Abot JL, Zestos AG. Perspective-Advances in Voltammetric Methods for the Measurement of Biomolecules. ECS Sens Plus. 2024;3(2):027001. doi: 10.1149/2754-2726/ad3c4f.
- Jara-Palacios MJ, et al. Effectiveness of Cyclic Voltammetry in Evaluation of the Synergistic Effect of Phenolic and Amino Acids Compounds on Antioxidant Activity: Optimization of Electrochemical Parameters. Foods. 2024; 13(6):906. https://doi.org/10.3390/foods13060906
- Jeremic J, et al. Monitoring Oxidative Status in Winemaking by Untargeted Linear Sweep Voltammetry. Foods. 2020; 9(6):728. https://doi.org/10.3390/foods9060728
- Rajendrachari S,et al. Assessing the Food Quality Using Carbon Nanomaterial Based Electrodes by Voltammetric Techniques. Biosensors (Basel). 2022;12(12):1173. doi: 10.3390/bios12121173.
- Alghamdi AH. Applications of stripping voltammetric techniques in food analysis. Arab J Chem. 2009; 3(1), 1-7. https://doi.org/10.1016/j.arabjc.2009.12.001
Further Reading