Electrochemical sensor based on graphene and mesoporous TiO2 for the simultaneous determination of trace colourants in food

Trends in pulse voltammetric techniques applied to foodstuffs analysis: The food additives detection

Food additives are chemical compounds intentionally added during foodstuff production to control technological functions, such as pH, viscosity, stability (color, flavor, taste, and odor), homogeneity, and loss of nutritional value. These compounds are fundamental in inhibition the degradation process and prolonging the shelf life of foodstuffs. However, their inadequate employment or overconsumption can adversely affect consumers' health with the development of allergies, hematological, autoimmune, and reproductive disorders, as well as the development of some types of cancer. Thus, the development and application of simple, fast, low-cost, sensitivity, and selectivity analytical methods for identifying and quantifying food additives from various chemical classes and in different foodstuffs are fundamental to quality control and ensuring food safety. This review presents trends in the detection of food additives in foodstuffs using differential pulse voltammetry and square wave voltammetry, the main pulse voltammetric techniques, indicating the advantages, drawbacks, and applicability in food analysis. Are discussed the importance of adequate choices of working electrode materials in the improvements of analytical results, allowing reliable, accurate, and inexpensive voltammetric methods for detecting these compounds in foodstuffs samples.

Spectral characterization of micellar-enhanced fluorescence of europium (III)-doxycycline complex and its employment as a sensor for development of a highly sensitive fluorimetric assay for determination of indigo carmine in real syrups

Indigo carmine (IN-CR) is a synthetic blue dye widely used as a coloring agent in various food and beverage products. It is recognized for its ability to enhance the visual appeal, hue, and consistency of food products. However, recent studies have raised concerns about the potential health risks associated with this substance. Therefore, a highly sensitive analytical tool is required for the trace determination of IN-CR in food products. This study describes the spectral characteristics of micellar-enhanced fluorescence of europium (III)-doxycycline complex and its employment as a sensor for the development of a highly sensitive fluorimetric assay for the trace determination of IN-CR. The complex was formed in an alkaline medium containing hydrogen peroxide and encapsulated into cetyltrimethylammonium bromide micelles. This micellar-encapsulated complex exhibited significantly enhanced fluorescence at a wavelength of 613.5 nm, overlapping with the maximum absorption peak of IN-CR at 610 nm. This inner-filter effect phenomenon resulted in IN-CR's concentration-dependent quenching of the complex's fluorescence. The fluorescence quenching of the complex by inner-filter effect of IN-CR was adopted in the development of a highly sensitive fluorimetric assay for IN-CR. The conditions of the assay were refined, and the optimum procedures were established. The assay was validated for its performance characteristics, and all the validation criteria were met. The assay displayed linearity within the IN-CR concentration range of 100-1250 ng mL-1, with a limit of detection at 41.2 ng mL-1. Importantly, the assay exhibited no interference from other substances commonly used as food additives. The recoveries ranged from 99.11 % to 101.57 %, with relative standard deviations ranging from 1.34 % to 1.89 %.The assay was successfully applied to the determination of IN-CR in commercial syrup products, and the recoveries ranged from 93.5 % to 106.32 % with relative standard deviations ≤4.72 %, confirming the reliability of the assay. The proposed assay provides some key advantages, including a novel application of the europium (III)-doxycycline complex as a fluorescence sensor for the determination of IN-CR in real syrups innovative, high sensitivity and selectivity, simplicity of analysis procedures, time-saving of entire analysis protocol. In conclusion, the assay serves as a valuable tool for quantifying IN-CR in food products, facilitating the assessment of both food quality and safety.

Nanoarchitecturing of Mo2C nanospheres on carbon cloth as an electrochemical sensing platform for determination of caffeic acid in tea samples

In the present paper, carbon cloth (CC) as a flexible substrate was modified by molybdenum carbide nanospheres (Mo2C NSs @CC) by the drop-coating method to develop a sensitive electrochemical platform for detecting caffeic acid. The uniform Mo2C NSs were prepared via an easy route followed by pyrolyzing the precursor of the Mo-polydopamine (Mo-PDA) NSs. The Mo2C NSs were characterized and analyzed by X-ray diffraction (XRD), field emission scanning electron microscopy/energy dispersive X-ray spectroscopy (FE-SEM/EDS), Raman spectroscopy (RS), and electrochemical methods. CC not only gave a flexible feature to the sensor but also provided a larger surface area for Mo2C NSs. Meanwhile, the excellent conductivity and large electroactive specific surface area of Mo2C NSs exhibited excellent electrocatalytic performance for caffeic acid determination. The developed sensor showed high sensitivity and selectivity, good reproducibility, and long-term stability with a limit of detection (LOD) and a wide linear range of 0.001 μM (S/N = 3) and 0.01-50 μM, respectively. In addition, the Mo2C NSs @CC sensor showed a promising application prospect for the detection of caffeic acid in green and black tea samples, indicating its importance in food safety and the food industry.

Recent advances in the use of composite titanium dioxide nanomaterials in the food industry

Titanium dioxide (TiO2 ) nanomaterials have attracted significant attention due to their good biocompatibility and potential for multifunctional applications. In the last few years, there has been growing interest in the use of TiO2 nanomaterials in the food industry. However, a systematic review of the synthesis methods, properties, and applications of TiO2 nanomaterials in the food industry is lacking. In this review, we provide a summary of the synthesis and properties of TiO2 nanomaterials and their composites, with a focus on their applications in the food industry. We also discuss the potential benefits and risks of using TiO2 nanomaterials in food applications. This review aims to promote food innovation and improve food quality and safety.

Voltammetric Sensor Based on the Combination of Tin and Cerium Dioxide Nanoparticles with Surfactants for Quantification of Sunset Yellow FCF

Sunset Yellow FCF (SY FCF) is one of the widely used synthetic azo dyes in the food industry whose content has to be controlled for safety reasons. Electrochemical sensors are a promising tool for this type of task. A voltammetric sensor based on a combination of tin and cerium dioxide nanoparticles (SnO2-CeO2 NPs) with surfactants has been developed for SY FCF determination. The synergetic effect of both types of NPs has been confirmed. Surfactants of various natures (sodium lauryl sulfate (SLS), Brij® 35, and hexadecylpyridinium bromide (HDPB)) have been tested as dispersive media. The best effects, i.e., the highest oxidation currents of SY FCF, have been observed in the case of HDPB. The sensor demonstrates a 4.5-fold-higher electroactive surface area and a 38-fold-higher electron transfer rate compared to the bare glassy carbon electrode (GCE). The electrooxidation of SY FCF is an irreversible, two-electron, diffusion-driven process involving proton transfer. In differential pulse mode in Britton-Robinson buffer (BRB) pH 2.0, the sensor gives a linear response to SY FCF from 0.010 to 1.0 μM and from 1.0 to 100 μM with an 8.0 nM detection limit. The absence of an interferent effect from other typical food components and colorants has been shown. The sensor has been tested on soft drinks and validated with the standard chromatographic method.

Development of a sensitive and inexpensive electrochemical sensor for indigotin using poly(valine) modified carbon paste electrode

In this study, an electro-polymerized valine (VLN) stimulated carbon paste electrode (CPE) was used to create a straightforward, inexpensive, and renewable electrochemical sensor for accurate and selective indigotin (IGN) determination. Comparing the CPE, to the modified electrode, it exhibits excellent sensibility for the IGN oxidation-reduction reaction. Multiple techniques, including cyclic voltammetry (CV), differential pulse voltammetry (DPV), electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM) were utilized in this case to characterize the electrode materials. IGN was analyzed using CPE and poly(valine) modified carbon paste electrodes (P(VLN)MCPE) taking a 6.5 pH in 0.2 M phosphate buffer solution (PBS). Because it has more active spots than the CPE and a strong electrocatalytic nature, P(VLN)MCPE exhibits excellent electrochemical performance. The impact of pH, scan rate, numerous interferents, and fluctuation in analyte concentration were only a few of the important electrochemical factors that were investigated. The variation in scan rate proves that the IGN oxidation-reduction reaction on the surface of P(VLN)MCPE is as follows an adsorption-controlled pathway. The P(VLN)MCPE displays a good electrochemical nature for IGN in the 0.2 to 5.0 μM range, with a low limit of detection (LOD) is 0.0069 μM and a limit of quantification (LOQ) is 0.023 μM. P(VLN)MCPE shows good reproducibility, stability, and repeatability for the detection of IGN. Additionally, P(VLN)MCPE's analytical applicability for IGN detection in water sample was assessed with impressive recovery.

2D-ReS2 & diamond nanoparticles-based sensor for the simultaneous determination of sunset yellow and tartrazine in a multiple-pulse amperometry FIA system

We present a flow injection system with a multiple pulse amperometric detection (FIA-MPA)-based methodology for the simultaneous analysis of sunset yellow and tartrazine. As transducer, we have developed a novel electrochemical sensor based on the synergistic effect of ReS₂ nanosheets and diamond nanoparticles (DNPs). Among several transition dichalcogenides for the sensor development, we have selected ReS₂ nanosheets since it yields a better response towards both colourants. Scanning probe microscopy characterization shows that the surface sensor is composed by scattered and stacked ReS₂ flakes and large aggregates of DNPs. With this system, the gap between the oxidation potential values of sunset yellow and tartrazine is wide enough to allow the simultaneous determination of both dyes. Under the optimum potential pulse conditions (0.8 and 1.2 V) during 250 ms, a flow rate of 3 mL/min and a volume injection of 250 μL, detection limits of 3.51 × 10^-7 M and 2.39 × 10^-7 M for sunset yellow and tartrazine, respectively, were obtained. This method exhibits good accuracy and precision with Er minor than 13% and RSD lower than 8% with a sampling frequency of 66 samples per hour. Pineapple jelly samples were analyzed by the standard addition method, obtaining 53.7 mg/kg and 29.0 mg/kg of sunset yellow and tartrazine, respectively. From the analysis of fortified samples, recoveries of 94% and 105% were obtained.

Analytical Applicability of Graphene-Modified Electrode in Sunset Yellow Electrochemical Assay

Due to the recent increase in average living standards, food safety has caught public attention. It is necessary to conduct a qualitative and quantitative rapid test of prohibited food additives since the inclusion of food additives or the improper usage of synthetic dyes can negatively impact on the human health. Herein, a highly sensitive method for Sunset Yellow detection based on a glassy carbon electrode modified with few-layer graphenes was proposed. The electrochemical behavior of SY at the GR-exf/GCE modified surface was investigated by Cyclic Voltammetry, Square Wave Voltammetry, Electrochemical Impedance Spectroscopy and Amperometry. The influences of pH, scan rate, and interfering species were studied. Under optimized conditions, the developed sensor shows good linearity over a broad SY concentration range, e.g., 0.028-30 µM, with a low limit of detection (LOD = 0.0085 µM) and quantification (LOQ = 0.028 µM) (data obtained by amperometric technique). Furthermore, the modified electrode shows good selectivity, precision and sensitivity and has been successfully applied for SY quantification from commercially available pharmaceutical formulation as well as from candy bars and orange juice.

Electropolymerized 4-Aminobenzoic Acid Based Voltammetric Sensor for the Simultaneous Determination of Food Azo Dyes

Electrochemical sensors with polymeric films as a sensitive layer are of high interest in current electroanalysis. A voltammetric sensor based on multi-walled carbon nanotubes (MWCNTs) and electropolymerized 4-aminobenzoic acid (4-ABA) has been developed for the simultaneous determination of synthetic food azo dyes (sunset yellow FCF and tartrazine). Based on the voltammetric response of the dyes' mixture, the optimal conditions of electropolymerization have been found to be 30-fold potential scanning between -0.3 and 1.5 V, at 100 mV s^-1 in the 100 µmol L^-1 monomer solution in phosphate buffer pH 7.0. The poly (4-ABA)-based electrode shows a 10.5-fold increase in its effective surface area and a 17.2-fold lower electron transfer resistance compared to the glassy carbon electrode (GCE). The sensor gives a sensitive and selective response to sunset yellow FCF and tartrazine, with the peak potential separation of 232 mV in phosphate buffer pH 4.8. The electrooxidation parameters of dyes have been calculated. Simultaneous quantification is possible in the dynamic ranges of 0.010-0.75 and 0.75-5.0 µmol L^-1 for both dyes, with detection limits of 2.3 and 3.0 nmol L^-1 for sunset yellow FCF and tartrazine, respectively. The sensor has been tested on orange-flavored drinks and validated with chromatography.

An Electrochemical Sensor for Sunset Yellow Detection Based on Cu@Cu2O-BNPC Formed by Modified Porous Carbon

Control and detection of sunset yellow (SY) are an utmost demanding issue due to its high risk of detrimental effects on living systems caused by excessive ingestion. In this study, we reported the synthesis of Cu@Cu₂O nanoparticle-decorated B and N codoped porous carbon (BNPC) and its use in developing a novel electrochemical sensor for SY. The Cu@Cu₂O-BNPC catalyst was fabricated through single-step polymerization, followed by carbonization. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy characterization results showed that Cu@Cu₂O anchored on the porous BNPC successfully. Compared with the BNPC-modified electrode, it was found that the Cu@Cu₂O-BNPC-modified electrode showed superior electrocatalytic activity in both electrochemical impedance spectroscopy and cyclic voltammetry tests. The as-prepared Cu@Cu₂O-BNPC catalyst directly acted as a sensor for amperometric detection of SY without further assembling, which exhibited an ultrahigh sensitivity of 0.09 μA nM^-1 cm^-2, a low limit of detection (2.4 nM), and a wide linear detection ranging from 10 nM to 8 μM. To further validate its possible application, the proposed method was successfully used for the determination of SY in Fanta drinks with satisfactory results.

Vanillin-crosslinked chitosan/ZnO nanocomposites as a drug delivery system for 5-fluorouracil: study on the release behavior via mesoporous ZrO2-Co3O4 nanoparticles modified sensor and antitumor activity

Herein, a series of vanillin-crosslinked chitosan (Vn-CS) nanocomposites (NCs) containing various contents of ZnO nanoparticles (NPs) was prepared and characterized via FTIR spectroscopy, XRD, TGA, SEM and TEM. Changing the weight% of ZnO NPs in the prepared NCs resulted in an improvement in their antibacterial activity against Gram-negative and Gram-positive bacteria strains compared with the unmodified CS, and the encapsulation efficiency of 5-fluorouracil (5-FU) was found to be in the range of 61.4–69.2%. Subsequently, the release of 5-FU was monitored utilizing the mesoporous ZrO₂–Co₃O₄ NPs modified carbon paste sensor via the square-wave adsorptive anodic stripping voltammetry (SW-AdASV) technique. Also, the release mechanism of 5-FU from each NC was studied by applying the zero-order, first-order, Hixson–Crowell and Higuchi models to the experimental results. The cytotoxicity of prepared NCs and 5-FU-encapsulated NCs was evaluated against the HePG-2, MCF-7 and HCT-116 cancer cell lines, in addition to the WI-38 and WISH normal cell lines using the MTT assay. Notably, 5-FU/CV₁₀ NC exhibited the highest antitumor activity towards all tested cancer cell lines and a moderate activity against WI-38 and WISH normal cell lines with IC₅₀ values of 28.02 ± 2.5 and 31.65 ± 2.7 μg mL⁻¹, respectively. The obtained nanocomposites exhibited suitable selectivity with minimum toxicity against normal cells.

Herein, a series of vanillin-crosslinked chitosan (Vn-CS) nanocomposites (NCs) containing various contents of ZnO nanoparticles (NPs) was prepared and characterized via FTIR spectroscopy, XRD, TGA, SEM and TEM.

Application of Graphene and its Derivatives in Detecting Hazardous Substances in Food: A Comprehensive Review

Graphene and its derivatives have been a burning issue in the last 10 years. Although many reviews described its application in electrochemical detection, few were focused on food detection. Herein, we reviewed the recent progress in applying graphene and composite materials in food detection during the past 10 years. We pay attention to food coloring materials, pesticides, antibiotics, heavy metal ion residues, and other common hazards. The advantages of graphene composites in electrochemical detection are described in detail. The differences between electrochemical detection involving graphene and traditional inherent food detection are analyzed and compared in depth. The results proved that electrochemical food detection based on graphene composites is more beneficial. The current defects and deficiencies in graphene composite modified electrode development are discussed, and the application prospects and direction of graphene in future food detection are forecasted.

Nanoarchitectonics of graphene based sensors for food safety monitoring

Since the desire for the real-time food quality monitoring, plenty of research effort has been made to develop novel tools and to offer extremely efficient detection of food contaminants. Unique electrical, mechanical, and thermal properties make graphene an important material in the field of sensor research. The material can be manufactured into flakes, sheets, films and with its oxidized derivatives could be almost used for a limitless set of application. Herein, current graphene-based sensors for food quality monitoring, novel designs, sensing mechanisms and elements of sensor systems and potential challenges will be outlined and discussed.

An Electrochemical Sensor Based on Carbon Paper Modified with Graphite Powder for Sensitive Determination of Sunset Yellow and Tartrazine in Drinks

The paper describes the development of an electrochemical sensor to be used for the determination of synthetic food colorants such as Sunset Yellow FCF (SY) and Tartrazine (TZ). The sensor is a carbon paper (CP) electrode, manufactured by using hot lamination technology and volume modified with fine-grained graphite powder (GrP). The sensor (GrP/CP) was characterized by scanning electron microscopy, energy dispersive spectrometry, electrochemical impedance analysis, cyclic, linear sweep and differential pulse voltammetry. The mechanism of SY and TZ electrochemical oxidation on GrP/CP was studied. The developed sensor has good electron transfer characteristics and low electron resistance, high sensitivity and selectivity. Applying the differential pulse mode, linear dynamic ranges of 0.005–1.0 μM and 0.02–7.5 μM with limits of detection of 0.78 nM and 8.2 nM for SY and TZ, respectively, were obtained. The sensor was used to detect SY and TZ in non-alcoholic and alcoholic drinks. The results obtained from drink analysis prove good reproducibility (RSD ≤ 0.072) and accuracy (recovery 96–104%).

Specific and Sensitive Detection of Tartrazine on the Electrochemical Interface of a Molecularly Imprinted Polydopamine-Coated PtCo Nanoalloy on Graphene Oxide

A novel electrochemical sensor designed to recognize and detect tartrazine (TZ) was constructed based on a molecularly imprinted polydopamine (MIPDA)-coated nanocomposite of platinum cobalt (PtCo) nanoalloy-functionalized graphene oxide (GO). The nanocomposites were characterized and the TZ electrochemical detection performance of the sensor and various reference electrodes was investigated. Interestingly, the synergistic effect of the strong electrocatalytic activity of the PtCo nanoalloy-decorated GO and the high TZ recognition ability of the imprinted cavities of the MIPDA coating resulted in a large and specific response to TZ. Under the optimized conditions, the sensor displayed linear response ranges of 0.003-0.180 and 0.180-3.950 µM, and its detection limit was 1.1 nM (S/N = 3). The electrochemical sensor displayed high anti-interference ability, good stability, and adequate reproducibility, and was successfully used to detect TZ in spiked food samples. Comparison of important indexes of this sensor with those of previous electrochemical sensors for TZ revealed that this sensor showed improved performance. This surface-imprinted sensor provides an ultrasensitive, highly specific, effective, and low-cost method for TZ determination in foodstuffs.

Application electrochemical sensor based on nanosheets G-C3N4/CPE by square-wave anodic stripping voltammetric for measure amounts of toxic tartrazine color residual in different drink and foodstuffs

The present work describes a method (SWASV) techniques for measure of tartrazine color a harmful compound present in real samples, and the extremely harmful to humans and animals even at low concentrations using G-C₃N₄ nanosheets sensor. Here, we report the use of an electrochemical approach for analytical determination of toxic tartrazine that takes 150 s. The calibration curve was linear in range of the (0.02-18.0 µmol L^-1). The current response was linearly proportional to the tartrazine concentration with a R²∼ 0.999. We demonstrated a sensitivity a limit of detection of (0.022 µmol L^-1). Finally, sensor nanosheets G-C₃N₄/CPE introduced to measure toxic tartrazine in different drink and foodstuff samples was used and the chemical nanosheets G-C₃N₄/CPE sensor made it possible as an excellent sensor with reproducibility for determination other samples.

One-Step Fabrication of Nickel-Electrochemically Reduced Graphene Oxide Nanocomposites Modified Electrodes and Application to the Detection of Sunset Yellow in Drinks

This work describes a straightforward method using one-step preparation of graphene/nickel nanocomposite materials from low-cost materials including graphene oxide and nickel metal. Repetitive CVs lead to the simultaneous deposition of metallic nickel nanoparticles and reduced graphene oxide sheets onto glassy carbon electrode. The obtained nanocomposite-modified surfaces were characterised by cyclic voltammetry, differential pulse voltammetry and field emission scanning electron microscopy. The result demonstrated the ability to produce nickel nanoparticles with a small size of about 20 nm, uniformly dispersed on a graphene oxide matrix. The ERGO-NiNP nanocomposite could be used as a sensor material exhibiting high performance; it is used here in order to detect Sunset Yellow (SY) and for quantification in complex media. The sensor enables rapid quantification of SY with a good linearity (R2 = 0.996) in the range of 10–1000 nM, together with a low detection limit of 3.7 nM (equivalent to 1.7 µg L−1) and a high sensitivity up to 7 µA/µM. The sensor also displays high reliability with a RSD value = 1.08 (n = 10) and good reusability (signal response variation below 5% after 5 detection/cleaning cycles). Finally, we demonstrate how this GCE/ERGO-NiNP sensor can be used for the successful determination of SY in commercial soft drink samples with an acceptable deviation below 6.4% when compared to HPLC method.

Pyridine ionic liquid functionalized bimetallic MOF solid-phase extraction coupled with high performance liquid chromatography for separation/analysis sunset yellow

An effective method based on the pyridine ionic liquid functionalized bimetallic MOF solid-phase extractant (Cu/Co-MOF@[PrPy][Br]) coupled with high performance liquid chromatography (HPLC) for the separation/analysis sunset yellow was established. Cu/Co-MOF@[PrPy][Br] was characterized by FTIR, XRD, SEM and TEM. Several important factors, such as pH, amount of extractant, extract time, and types of eluents were investigated in detail. Under the optimal conditions, linear range of the method was 0.05–40.00 μg mL⁻¹, the detection limit was 0.02 μg mL⁻¹, and the linear correlation was good (R² = 0.9992). The analysis of sunset yellow in soda, effervescent tablet and jelly proved that the method was simple and effective.

An effective method based on the pyridine ionic liquid functionalized bimetallic MOF solid-phase extractant (Cu/Co-MOF@[PrPy][Br]) coupled with high performance liquid chromatography (HPLC) for the separation/analysis sunset yellow was established.

Three-dimensional porous reduced graphene oxide decorated with carbon quantum dots and platinum nanoparticles for highly selective determination of azo dye compound tartrazine

In this work, an electrochemical sensor for the azo dye compound tartrazine (TRT) determination was proposed. A screen-printed carbon electrode (SPCE) was modified by depositing three-dimensional porous reduced graphene oxide decorated with carbon quantum dots and platinum nanoparticles (Pt/CQDs@rGO/SPCE). The resulting amount of TRT was observed by differential pulse voltammetry. Under optimal conditions, the sensor exhibited two wide linearities ranging from 0.01 to 1.57 μM and 1.57-9.3 μM with the reliability coefficient of determination of 0.991 and 0.992, respectively. The detection limit (LOD) was also estimated to be 7.93 nM. Moreover, the Pt/CQDs@rGO/SPCE suggested high selectivity in the presence of several interfering agents and azo dye compounds that have a similar structure. Additionally, the Pt/CQDs@rGO/SPCE revealed superior recovery values of about 96.5-101.6% for candy, 99.7-103.5% for soft drinks, 96.0-101.2% for jelly powder, and 98.0-103.0% for water samples. Furthermore, the fabricated sensor exhibits excellent selectivity, stability, reproducibility, and repeatability, indicating a great perspective in the monitoring of TRT. Therefore, it can be speculated that the proposed electrode could be effectively applied to determine TRT in food samples.

Detection of tartrazine in fake saffron containing products by a sensitive optical nanosensor

A fluorescent assay for the selective analysis of tartrazine was developed. Tartrazine is a health-threatening food additive commonly used as fake saffron. An optical nanosensor was fabricated based on molecular imprinting technique in which carbon dots (CDs) as fluorophores and tartrazine as a template molecule were embedded in molecularly imprinted polymer (MIP) matrix. The synthesized CDs embedded in MIP (CDs-MIP) was characterized by various methods. The fluorescence intensity of (CDs-MIP) was selectively quenched in the presence of tartrazine in comparison with other similar food color additives. The correlation between the quenching of CD-MIP and the concentration of tartrazine was used as an optical sensing for rapid detection of tartrazine in the range of 3.3-20.0 nM (1.8-10.7 μg L^-1) with detection limit of 1.3 nM (0.70 μg L^-1). Eventually, the designed nanosensor was successfully applied for tartrazine detection in foodstuffs such as fake saffron, saffron tea and saffron ice cream samples.

A Simple but Efficient Voltammetric Sensor for Simultaneous Detection of Tartrazine and Ponceau 4R Based on TiO2/Electro-Reduced Graphene Oxide Nanocomposite

In this work, we report a simple but efficient voltammetric sensor for simultaneous detection of ponceau 4R and tartrazine based on TiO2/electro-reduced graphene oxide nanocomposites (TiO2/ErGO). TiO2/ErGO nanocomposites were prepared by ultrasonically dispersing TiO2 nanoparticles (TiO2 NPs) into graphene oxide (GO) solution followed by a green in-situ electrochemical reduction. TiO2 NPs were uniformly supported on ErGO nanoflakes, which provides a favorable interface for the adsorption and subsequent oxidation of target analytes. TiO2/ErGO showed remarkable electrocatalytic capacity for the oxidation of ponceau 4R and tartrazine, with minimized oxidation overpotentials and boosted adsorptive striping differential pulse voltammetric (AdSDPV) response peak currents. Under the optimal experimental conditions, the anodic peak currents of ponceau 4R and tartrazine increase linearly with the respective natural logarithm of concentrations from 0.01 to 5.0 μM. The detection limits (LOD = 3σ/s) for ponceau 4R and tartrazine are 4.0 and 6.0 nM, respectively. The extraordinary analytical properties of TiO2/ErGO/GCE are primarily attributed to the synergistic enhancement effect from ErGO nanoflakes and TiO2 NPs. Moreover, the proposed TiO2/ErGO/GCE achieves reliable determination of ponceau 4R and tartrazine in orange juice with excellent selectively, reproducibility and stability. Together with simplicity, rapidness, and low cost, the proposed sensor demonstrates great potential for on-site detection of azo colorants.

Graphitic carbon nitride/graphene nanoflakes hybrid system for electrochemical sensing of DNA bases in meat samples

This research presents a simple, fast and simultaneous electrochemical quantitative determination of nucleobases, for example guanine (G), adenine (A), and thymine (T) in a beef and chicken livers samples to measure the quality of food products based on hybrids of graphitic carbon nitride/Graphene nanoflakes (g-C₃N₄/GNF) modified electrode. Graphitic carbon nitride (g-C₃N₄) made of graphite-like covalent link connects nitrogen, nitride, and carbon atoms in the structural design with improved the electrical properties and low band gap semiconductor. The g-C₃N₄/GNF nanocomposite was synthesized by the hydrothermal treatment to form a porous g-C₃N₄ interconnected three dimensional (3D) network of g-C₃N₄ and GNF. The 3D g-C₃N₄/GNF/GCE was utilized for the detection of nucleic acid bases with a well resolved oxidation peak for the individual analyte. The electrocatalytic current was established to be a linear range from 0.3 × 10^–7 to 6.6 × 10^–6, 0.3 × 10^–7 to 7.3 × 10^–6, and 5.3 × 10⁻⁶ to 63.3 × 10⁻⁴ M for G, A, and T with a detection limit of 4.7, 3.5 and 55 nM, respectively. The diffusion co-efficient and the kinetic parameters were derived from the chronoamperometry technique. The proposed sensing strategy has been effectively used for the application in real sample analysis and observed that the electrode free from the surface fouling.

A Review on the Use of Impedimetric Sensors for the Inspection of Food Quality

This paper exhibits a thorough review of the use of impedimetric sensors for the analysis of food quality. It helps to understand the contribution of some of the major types of impedimetric sensors that are used for this application. The deployment of impedimetric sensing prototypes has been advantageous due to their wide linear range of responses, detection of the target analyte at low concentrations, good stability, high accuracy and high reproducibility in the results. The choice of these sensors was classified on the basis of structure and the conductive material used to develop them. The first category included the use of nanomaterials such as graphene and metallic nanowires used to form the sensing devices. Different forms of graphene nanoparticles, such as nano-hybrids, nanosheets, and nano-powders, have been largely used to sense biomolecules in the micro-molar range. The use of conductive materials such as gold, copper, tungsten and tin to develop nanowire-based prototypes for the inspection of food quality has also been shown. The second category was based on conventional electromechanical circuits such as electronic noses and other smart systems. Within this sector, the standardized systems, such as electronic noses, and LC circuit -based systems have been explained. Finally, some of the challenges posed by the existing sensors have been listed out, along with an estimate of the increase in the number of sensors employed to assess food quality.

Electrochemiluminescence Detection of Sunset Yellow by Graphene Quantum Dots

Use of food additives, such as colorants and preservatives, is highly regulated because of their potential health risks to humans. Therefore, it is important to detect these compounds effectively to ensure conformance with industrial standards and to mitigate risk. In this paper, we describe the preparation and performance of an ultrasensitive electrochemiluminescence (ECL) sensor for detecting a key food additive, sunset yellow. The sensor uses graphene quantum dots (GQDs) as the luminescent agent and potassium persulfate as the co-reactant. Strong and sensitive ECL signals are generated in response to trace amounts of added sunset yellow. A detection limit (signal-to-noise ratio = 3) of 7.6 nM and a wide linear range from 2.5 nM to 25 μM are demonstrated. A further advantage of the method is that the luminescent reagents can be recycled, indicating that the method is sustainable, in addition to being simple and highly sensitive.

Synthetic Food Dyes – Some Aspects Of Use And Methods Of Determination

Color is one of the key ingredients for increasing the appetizing of food, so food dyes have become firmly established in food production technologies. However, with the acquisition of toxicity data of synthetic food dyes (SFD), there were restrictions and standards for their content in food have emerged. Numerous papers published in recent years demonstrate the importance of the problem of the use and definition of SFD. The review contains over 180 literary references in the field of usage and methods of determination of synthetic food dyes, among them regulatory documents (regulations), official internet resources of international and Ukrainian organizations, review articles and original works. Varieties of chromatography, enzyme-linked immunoassay, optical and electrochemical methods are used to identify and determine SFD. Special attention was paid to voltammetry (VA) as a method that is cheaper than chromatography and completely satisfies selectivity, sensitivity, reliability requirements and is compatible with the concept of green analytical chemistry, as it doesn't need organic solvents. Moreover, single sweep voltammetry can be considered as a screening method with low limits of determination and rapid respons

Highly sensitive and rapid determination of sunset yellow in drinks using a low-cost carbon material-based electrochemical sensor

Starting from simple graphite flakes, an electrochemical sensor for sunset yellow monitoring is developed by using a very simple and effective strategy. The direct electrochemical reduction of a suspension of exfoliated graphene oxide (GO) onto a glassy carbon electrode (GCE) surface leads to the electrodeposition of electrochemically reduced oxide at the surface, obtaining GCE/ERGO-modified electrodes. They are characterized by cyclic voltammetry (CV) measurements and field emission scanning electron spectroscopy (FE-SEM). The GCE/ERGO electrode has a high electrochemically active surface allowing efficient adsorption of SY. Using differential pulse voltammetry (DPV) technique with only 2 min accumulation, the GCE/ERGO sensor exhibits good performance to SY detection with a good linear calibration for concentration range varying 50-1000 nM (R² = 0.996) and limit of detection (LOD) estimated to 19.2 nM (equivalent to 8.9 μg L^-1). The developed sensor possesses a very high sensitivity of 9 μA/μM while fabricated with only one component. This electrochemical sensor also displays a good reliability with RSD value of 2.13% (n = 7) and excellent reusability (signal response change < 3.5% after 6 measuring/cleaning cycles). The GCE/ERGO demonstrates a successful practical application for determination of sunset yellow in commercial soft drinks. Graphical abstract.

An electrochemical sensor for the determination of tartrazine based on CHIT/GO/MWCNTs/AuNPs composite film modified glassy carbon electrode

A novel nanocomposite film of chitosan/graphene oxide (CHIT/GO)/multi-walled carbon nanotubes (MWCNTs)/gold nanoparticles (AuNPs) was applied to fabricate glassy carbon electrode (CHIT/GO/MWCNTs/AuNPs/GCE) for the determination of Tartrazine (TZ), synthetic dyes in food products. The electrochemical sensors found it to be highly sensitive by combining the signal amplification properties of GO and the excellent electronic and antifouling properties of MWCNTs. The CHIT/GO/MWCNTs/AuNPs/GCE exhibited as superior electron transfer materials and possesses intercalation properties which provide synergistic influence on the increment of the current signals. The optimum conditions were found at pH 7, 30 s, and 0.3 Vs^-1. The modified GCE obtained with a linear response ranging from 10 to 100 mg mL^-1 (r² = 0.99037) with a sensitivity of 0.018 μA μM^-1. The limit of detection (LOD) and quantification obtained were 1.45 and 4.83 mg mL^-1, respectively. The determination of TZ in spiked samples was reliable with recovery percentage from 94.52 to 109.0%. The developed sensor successfully tested in the determination of TZ analyte in commercial candy, jelly, and soft drinks with acceptable results.