Recent advances in electrochemical sensors based on nanomaterials for detection of red dyes in food products: A review

Red dyes as Allura Red (E129), Amaranth (E124), Ponceau 4R (E123), Erythrosine (E127) and Carmoisine (E122), are very popular food additives due to their stability, low cost, and minimal microbial contamination. Despite these advantages, their consumption may result in asthma, hyperactivity, carcinogenic effects, etc depending on the uptake and age. Therefore, the United States Food and Drug Administration (FDA) and European Food Safety Authority (EFSA) have managed the permissions of allowed daily intake (ADI) for consumption levels of these dyes to be 0.01-7.0 mg/kg to assure foodstuffs consumer's safety and avoid their adverse effects. Yet, many countries as Japan and USA have prohibited their use in food and drinks to reduce their possible health risks. Based on the above concentration ranges, highly sensitive and selective detection techniques are required, accordingly, the application of electrochemical sensors for the analysis of these dyes in food samples is very promising due to their superior sensitivity and selectivity, low cost and rapid response compared to traditional spectrophotometric or chromatographic methods. Also, they can be miniaturized, portable and require no complicated sampling or preparation procedures, besides being ecofriendly which allows their commercialization for public consumers in fast detection kits. In this review, the role of nanomaterials such as: carbon-based, transition metal oxides, metal organic frameworks, ionic liquids and others in enhancing the detection properties of modified electrochemical sensors for red dyes will be evaluated in terms of the type of nanomaterial applied, tested food samples and their impact on the evaluation of foodstuffs quality.

ZnO Hollow Quasi-Spheres Modified Screen-Printed Graphite Electrode for Determination of Carmoisine

Food colorants are important in food selection because they improve the gastronomic appeal of foods by improving their aesthetic appeal. However, after prolonged use, many colorants turn toxic and cause medical problems. A synthetic azo-class dye called carmoisine gives meals a red color. Therefore, the carmoisine determination in food samples is of great importance from the human health control. The current work was developed to synthesis ZnO hollow quasi-spheres (ZnO HQSs) to prepare a new electrochemical carmoisine sensor that is sensitive. Field emission-scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD) have been used to analyze the properties of prepared ZnO HQSs. A screen-printed graphite electrode (SPGE) surface was modified with ZnO HQSs to prepare the ZnO HQSs-SPGE sensor. For carmoisine detection, the ZnO HQSs-SPGE demonstrated an appropriate response and notable electrocatalytic activities. The carmoisine electro-oxidation signal was significantly stronger on the ZnO HQSs-SPGE surface compared to the bare SPGE. Cyclic voltammetry (CV), linear sweep voltammetry (LSV), chronoamperometry (CHA), and differential pulse voltammetry (DPV) have been utilized to investigate the suggested protocol. The DPV results revealed an extensive linear association between variable carmoisine concentrations and peak current that ranged from 0.08 to 190.0 µM, with a limit of detection (LOD) as narrow as 0.02 µM. The ZnO HQSs-SPGE's ability to detect carmoisine in real samples proved the sensor's practical application.

Advancement in electrochemical strategies for quantification of Brown HT and Carmoisine (Acid Red 14) Drom Azo Dyestuff class

Brown HT and carmoisine, which are the most used dyestuffs in pharmaceuticals, textiles, cosmetics and foods, are important components of the Azo family. Although the Azo group is not toxic or carcinogenic under normal conditions, these dyestuffs require great care due to the reduction of the Azo functional group to amines. In particular, fast, reliable, easy, on-site and precise determinations of these substances are extremely necessary and important. In this review, the properties, applications, and electrochemical determinations of brown HT and carmoisine, which are used as synthetic food colorants, are discussed in detail. Up to now, sensor types, detection limits (LOD and LOQ), and analytical applications in the developed electrochemical strategies for both substances were compared. In addition, the validation parameters such as the variety of the sensors, sensitivity, selectivity and electrochemical technique in these studies were clarified one by one. While the electrochemical techniques recommended for brown HT were mostly used for the removal of dyestuff, for carmoisine they included fully quantitative centered studies. The percentiles of voltammetric techniques, which are the most widely used among these electroanalytical methods, were determined. The benefits of a robust electrochemical strategy for the determination of both food colors are summed up in this review. Finally, the brown HT and carmoisine suggestions for future perspectives in electrochemical strategy are given according to all their applications.

Simultaneous detection of carmoisine and tartrazine in food samples using GO-Fe3O4-PAMAM and ionic liquid based electrochemical sensor

This study was performed to investigate the simultaneous detection of carmoisine and tartrazine, two food azo dyes, with a new voltammetric sensor based on graphene oxide-Fe3O4 (GO-Fe3O4) nanocomposite functionalized with fourth-generation poly(amidoamine) (G4 PAMAM) dendrimers (GO-Fe3O4-G4 PAMAM) and ionic liquid (IL) modified carbon paste electrode (GO-Fe3O4-G4 PAMAM/ILCPE). The GO-Fe3O4-G4 PAMAM was synthesized and characterized by X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), vibrating-sample magnetometer (VSM), and fourier transform infrared (FT-IR) techniques. Cyclic voltammetry (CV) was used to evaluate the electrochemical behavior of carmoisine, revealing the good electrocatalytic function of GO-Fe3O4-G4 PAMAM/ILCPE. Linear response from 0.1 to 170.0 μM was obtained based on carmoisine electrochemical oxidation through differential pulse voltammetry (DPV). The limit of detection (LOD) value obtained was 0.02 μM. Also, the GO-Fe3O4-G4 PAMAM/ILCPE was used for the simultaneous determination of carmoisine and tartrazine. In co-existence system containing carmoisine and tartrazine, the developed sensor exhibited well-defined and separate DPV peaks (i.e., 770 mV) for carmoisine and tartrazine. Besides, repeatability, reproducibility and stability studies were performed. Additionally, the analytical application of this sensor was demonstrated by determination of carmoisine and tartrazine in food samples including lemon juice and powdered juice.

A Short Review on Electrochemical Sensing of Commercial Dyes in Real Samples Using Carbon Paste Electrodes

Synthetic dyes are commonly used in food products like soft drinks, vegetable sauces, jellies, etc. Most artificial dyes can cause cancer, therefore it is very important to develop sensors to detect them in food samples. Voltammetric methods with carbon paste electrodes (CPEs) are promising for this purpose. However, modification of CPEs is necessary to detect the commercial dyes in food samples in the presence of interferents. In the current review, we have discussed the different previous research in which detection of dyes is performed in real samples with good detection limits. The current review will be helpful for readers who are interested in developing low-cost electrodes for the effective determination of dyes in commercial products like soft drinks and vegetable sauces.