Electrochemical sensor for hazardous food colourant quinoline yellow based on carbon nanotube-modified electrode

Highly Sensitive Voltammetric Method for Quinoline Yellow Determination on Renewable Amalgam Film Electrode

A novel electrochemical method for the determination of quinoline yellow (QY) was developed using the renewable amalgam film electrode (Hg(Ag)FE). The sensors used can be characterized by good stability and long lifespan. Irreversible QY reduction peaks were recorded in 0.05 mol L^-1 HCl with a potential of about -630 mV. The use of the Hg(Ag)FE electrode with a regulated working surface allowed the QY limit of detection to be as low as 0.48 nmol L^-1. The obtained result is the lowest in comparison to other voltammetric methods described in the literature. The effects of parameters such as the size of the working electrode surface, influence of the pH value, accumulation time, and potential were investigated to provide precision and high sensitivity of the performed measurements. This new procedure was applied for the highly sensitive determination of quinoline yellow in different beverages, pre-workout supplements, and throat lozenges. The process of sample preparation was relatively simple. Calculated recoveries (96-107%) suggest that the method can be considered accurate.

Enhanced reactivity of the CuO-Fe2O3 intimate heterojunction for the oxidation of quinoline yellow dye (E104)

This research work describes the degradation of quinoline yellow (QY) in aqueous solutions by the heterogeneous Fenton and photo-Fenton processes in the presence of CuO/Fe₂O₃ photocatalyst. CuO/Fe₂O₃ derived from LDH structure was synthesized by the co-precipitation method. The physiochemical characteristics of CuO/Fe₂O₃ were described by XRD, TEM/SEM, BET surface area, and FTIR techniques. The effects of pH, H₂O₂ concentration, dye concentration, catalyst dose, reaction temperature, and reusability of catalyst on the QY decolorization efficiency were studied. The results indicated that a complete removal of QY was achieved within 150 min, when the H₂O₂ and QY concentrations were 27.6 mM and 100 mg/L, respectively. The rate constants for QY removal by the heterogeneous Fenton system were calculated, and the experimental data were found to fit the pseudo-first order model. Under optimal conditions, the rate constants were, respectively, 0.02032 and 0.01715 min^-1 for the photo-Fenton and Fenton systems; this means that the addition of light has not a noticeable effect.

Filter paper-based colorimetric analysis: An instrument-free strategy for semiquantitative naked-eye detection of food colorants

A filter paper-based colorimetric strategy for instrument-independent visual detection of artificial food colorants (FCs) was developed in this study. Indicator papers were prepared via the one-step polycondensation of silane coupling agents onto glass microfiber filter papers, and colorimetric cards with a fine one-to-one correspondence between their colors and FCs concentrations were straightforward obtained by the extraction of FCs with indicator papers by virtue of electrostatic interaction and hydrophobic effect. Filter papers post-modified via such a simple way were proved to be of improved binding class selectivity and colorimetric sensitivity, allowing for in-situ colorimetric assay of FCs in an unprecedently wide range of applicable pH (1.0-12.0) with high reliability and fine versatility. Finally, the semiquantitative naked-eye determination of FCs (Allura red, brilliant blue and sunset yellow) in real-world drink samples was experimentally confirmed to be feasible by comparison with the findings of UV-vis absorption spectra, HPLC and mass spectra.

A cationic surfactant-decorated liquid crystal-based sensor for sensitive detection of quinoline yellow

Quinoline yellow (QY) is one of the popular synthetic food colorants and in food industry greatly used. Developing accurate and simple QY detection procedures is of major considerable importance in ensuring food safety. Hence, it is important to detect this food colorant effectively to reduce risk. Herein, an innovative liquid crystal (LC)-based sensor was designed for the label-free and ultra-sensitive detecting of the QY by means of a cationic surfactant-decorated LC interface. The nematic liquid crystal in touch with CTAB revealed a homeotropic alignment, when QY was injected into the LC-cell, the homeotropic alignment consequently altered to a planar one by electrostatic interactions between QY and CTAB. The designed LC-based sensor detected QY at the too much trace level as low as 0.5 fM with analogous selectivity. The suggested LC-based sensor is a rapid, convenient and simple procedure for label-free detection of QY in food industrial and safety control application.

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.

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

Sensitive determination of Amaranth in drinks by highly dispersed CNT in graphene oxide "water" with the aid of small amounts of ionic liquid

Graphene oxide (GO) is a pH-dependent amphiphile. In this paper, it was found that carbon nanotubes (CNTs) can be highly dispersed in graphene oxide "water" with the aid of prototype ionic liquid of 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM][PF6]). The introduction of [BMIM][PF6] not only can minimize the defects of poor electrical conductivity of GO, but also can improve the dispersibility of CNT in water. Hence, a new composite of CNT/GO-[BMIM][PF6] with high dispersibility and strong conductivity was presented for the first time and employed in the sensitive determination of Amaranth in soft drinks. The detection limit achieved (0.1 nM) is much lower than the guideline values in soft drinks. The ease of preparation, low background current, high sensitivity and stability can create novel avenues and applications for fabricating robust sensors for determination of other azo dyes in foods.