Allura Red Research Articles

Highly sensitive voltammetric determination of Allura Red (E129) food colourant on a planar carbon fiber sensor modified with shungite

This article presents an original planar carbon fiber electrode (PCFE), in which shungite (SHU) is used as a modifier for the first time. Shungite is a unique natural nanostructured composite consisting of carbon in the form of aggregated graphene stacks, oxides of silicon, titanium, aluminum, iron, magnesium, potassium, etc. Macro- and micro-elements, biologically active components that are present in shungite provide it with attractive antioxidant properties, make it a biocompatible and environmentally friendly material that meets the principles of green chemistry. A unique supramolecular structure of shungite carbon presents a multilayer globular-cluster formation with mesopores in the internal volume. It determines specific physical, chemical, catalytic, and adsorption properties of shungite. Carbon fiber with an irregular 3D structure was used as an effective electrode platform for strong immobilization of shungite. The PCFE was fabricated using a simple and scalable hot lamination technology that produces very low cost flexible planar electrodes. The sensor (SHU/PCFE) was characterized by scanning electron microscopy; electrochemical impedance analysis; cyclic, differential-pulse and stripping voltammetry. The SHU/PCFE showed a 2.5-fold increase in the electroactive surface area, a 1.8-fold decrease in the electron transfer resistance compared with the bare PCFE. Under optimal experimental conditions and preconcentration at +0.2 V (vs. Ag/AgCl) 180 s, the developed sensor allowed the quantification of Allura Red in the ranges of 0.001–0.1 and 0.1–2 μmol L−1 with an extremely low detection limit of 0.36 nmol L−1. Moreover, this convenient and cost-effective sensor also has good repeatability, stability and anti-interference ability. The interfering effect of sweeteners and preservatives in the determination of Allura Red does not exceed 3.6%. The practical application of the SHU/PCFE was demonstrated using drink samples, lollipops and pharmaceuticals.

The Influence of Ag+/Ti4+ Ratio on Structural, Optical and Photocatalytic Properties of MWCNT–TiO2–Ag Nanocomposites

In this paper, we propose a simple procedure to obtain multi-walled carbon nanotubes (MWCNTs) decorated with TiO2–Ag nanoparticles (MWCNT–TiO2–Ag). The MWCNTs were decorated with TiO2–Ag via combined functionalization with –OH and –COOH groups and a polymer-wrapping technique using poly(allylamine)hydrochloride (PAH). TiO2-modified Ag nanoparticles were synthesized via the Pechini method using a mixture of acetylacetonate-modified titanium (IV) isopropoxide with silver nitrate (with Ag+/Ti4+ atomic ratios of 0.5%, 1.0%, 1.5%, 2.0%, and 2.5%) and L(+)-ascorbic acid as reducing agents. XRD analysis revealed the formation of nanocomposites containing CNT, anatase TiO2, and Ag. The presence of nanoparticles on the MWCNT surfaces was determined using TEM. The morphology of the TiO2–Ag nanoparticles on the MWCNT surfaces was also determined using TEM. UV–Vis investigations revealed that an increase in the ratio between Ag+ and Ti4+ decreased the band gap energy of the samples. The characteristic vibrations of the TiO2, Ag, and C atoms of the graphite were identified using Raman spectroscopy. The photocatalytic activity of the MWCNT–TiO2–Ag nanocomposite was assessed by examining the degradation of Allura Red (E129) aqueous solution under UV irradiation. The dye photodegradation process followed a pseudo-first-order kinetic with respect to the Langmuir–Hinshelwood reaction mechanism. The spin-trapping technique evidenced that •O2− was the main species generated responsible for the Allura Red degradation.

Synthesis of doped and porous CuO with boosted light-harvesting features for the photocatalytic mineralization of azo dyes

Porous Ni-doped copper oxide (NCO) photocatalyst has been produced using chemical activation and metal doping techniques. Structural, optical, morphological, and electrical analyses were performed on copper oxide (CO) and porous NCO photocatalysts. The monoclinic-phased, UV/Vis light-triggered, electrically conductive, and porous-surfaced NCO photocatalyst was successfully synthesized, according to a detailed physicochemical investigation. The photo-decomposition abilities of synthetic porous NCO and counterpart CO photocatalysts were investigated and compared using Allura red (AR). According to the photocatalytic study, the porous NCO photocatalyst outperformed its counterpart (CuO) and eliminated 91.4% (adsorption: 18%; decomposition: 79%) of the AR dye in 48 min. Over the porous NCO photocatalyst, the AR dye disintegrated at a rate of 0.024 min−1, which is more than 1.84 times quicker than the rate of disintegration over the CO photocatalyst. The porous NCO photocatalyst, as synthesized, preserved 88% of its photocatalytic activity after five recyclability tests and had remarkable electron-hole separation activity, according to reusability tests and transient-photocurrent measurements. Also, the radical capture experiment suggested that superoxide and hydroxyl are important for porous NCO's photocatalytic activity. According to the findings of this research, the synthesis of ferromagnetic metal-doped and porous semiconductive materials has a great potential for azo dye breakdown, which makes it an efficient, cost-effective, and environmentally acceptable solution for the clean-up of polluted water.

Determination of Concentration of Food Dyes in Powdered Drink Mixes

Federal Food, Drug, and Cosmetic Act (FD&C) food dyes make industrial goods like foods and beverages more appealing. These dyes are synthetic and are typically used instead of natural dyes due to their color, stability, and low cost. Research has implied that children are sensitive to the amount of food dye in products. The amount of food dye in products is proprietary information, so it can be challenging to determine how much dye children are ingesting. In this study, ultraviolet-visible spectroscopy (UV-Vis) was utilized to find the concentration of food dyes in various powdered drink mixes. The results show that powdered drink mixes containing Red 40 have higher concentrations of food dye than the rest of the drink mixes. Our data supports that there is a difference between the concentrations of food dyes within drink mixes containing Red 40 versus those without it. These concentrations depend on the dye and how many dyes were in the drink mix.

One-Step, On-Site Chemical Printing of a 3D Plasmon-Coupled Silver Nanocoral Substrate toward SERS-Based POCT

Surface-enhanced Raman scattering (SERS) with the advantages of high sensitivity, nondestructive analysis, and a unique fingerprint effect shows great potential in point-of-care testing (POCT). However, SERS faces challenges in rapidly constructing a substrate with high repeatability, homogeneity, and sensitivity, which are the key factors that restrict its practical applications. In this study, we propose a one-step chemical printing strategy for synthesizing a three-dimensional (3D) plasmon-coupled silver nanocoral (AgNC) substrate (only need about 5 min) without any pretreatments and complex instruments. The galvanic replacement between AgNO3 and Cu sheets will provide both Ag0 for the formation of silver nanostructures and Cu2+ for the polymerization of fish sperm DNA (FSDNA). The protection of AgNCs is facilitated by the crosslinked FSDNA, which can improve the stability of the substrate and promote the control of its coral-like morphology. The obtained substrate displays excellent capacity of signal enhancement due to the 3D plasmon coupling both between nanocoral tentacles and between nanocorals and Cu sheets as well. Therefore, the AgNC substrates display high activity (enhancement factor = 1.96 × 108) and uniformity (RSD < 6%). Food colorants have been widely used in various foods to improve their color, but the inevitable toxicity of colorants seriously threatens food safety. Therefore, the proposed AgNC substrates were used to directly quantify three kinds of weak-affinity food colorant molecules including Brilliant Blue, Allura Red, and Sunset Yellow assisted by the capture by cysteamine hydrochloride (CA), showing the detection limits (S/N = 3) of 0.053, 0.087, and 0.089 ppm, respectively. The SERS method has been further applied in the detection of the three kinds of food colorants in both complex food samples and urine with recoveries of 91-119%. The satisfactory detection results suggest that the facile preparation strategy of AgNC substrates will be widely used in SERS-based POCT to promote the development of food safety and on-site healthcare.

Aqueous Two-Phase Systems Based on Cationic and Anionic Surfactants Mixture for Rapid Extraction and Colorimetric Determination of Synthetic Food Dyes.

In this study, aqueous two-phase systems (ATPSs) containing a cationic and anionic surfactants mixture were used for the preconcentration of the synthetic food dyes Allura Red AC, Azorubine, Sunset Yellow, Tartrazine, and Fast Green FCF. A rapid, simple, low cost, affordable, and environmentally friendly methodology based on microextraction in ATPSs, followed by spectrophotometric/colorimetric determination of the dyes, is proposed. The ATPSs are formed in mixtures of benzethonium chloride (BztCl) and sodium N-lauroylsarcosinate (NaLS) or sodium dihexylsulfosuccinate (NaDHSS) under the molar ratio close to equimolar at the total surfactant concentration of 0.01-0.20 M. The density, viscosity, polarity, and water content in the surfactant-rich phases at an equimolar ratio BztCl:NaA were determined. The effects of pH, total surfactant concentration, dye concentration, and time of extraction/centrifugation were investigated, and the optimum conditions for the quantitative extraction of dyes were established. The smartphone-based colorimetric determination was employed directly in the extract without separating the aqueous phase. The analytical performance (calibration linearity, precision, limits of detection and quantification, reproducibility, and preconcentration factor) and comparison of the spectrophotometric and smartphone-based colorimetric determination of dyes were evaluated. The method was applied to the determination of dyes in food samples and food-processing industrial wastewater.

Efficient Removal and Conditions Optimization of Textile Dyes Using UV/TiO&lt;sub&gt;2&lt;/sub&gt; Based Advanced Oxidation Process

Textile and other dye house effluents from different industries have many worst effects on aquatic as well as non-aquatic life. The present work was carried out for the conditions optimization of degradation of Allura Red AC dye. This was done by UV treatment and examining the effects of different parameters on degradation i.e. pH, concentration of the dye, temperature, radiation exposure time and concentration of TiO2. The efficiency of the treatment was monitored by checking the highest degradation value, parameters of water quality such as chemical oxygen demand (COD), biological oxygen demand (BOD) and toxicity. The end products of degradation of dye were checked out by UV/visible spectrophotometer, Fourier transform- infra red (FT-IR) and gas chromatographymass spectrometry (GC-MS) techniques. From the results, it was concluded that the degradation efficiency was in the order UV/H2O2/TiO2> UV/H2O2> UV alone. Furthermore, it was also concluded that UV/H2O2/TiO2 could be implemented on industrial scale for the removal of the toxic pollutants from industrial effluents.

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Gastrointestinal NursingVol. 21, No. 2 NewsNewsMelissa McAleesMelissa McAleesE-mail Address: [email protected] Twitter: @MfjMcaleesFreelance journalistSearch for more papers by this authorMelissa McAleesPublished Online:17 Mar 2023https://doi.org/10.12968/gasn.2023.21.2.14AboutSectionsView articleView Full TextPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsPermissions ShareShare onFacebookTwitterLinked InEmail View article References Activia. What the gut? 2023. www.danoneactivia.co.uk/about-gut-healthco/ (accessed 12 February 2023) Google ScholarTakeda UK Ltd. Levelling up care for people living with Inflammatory Bowel Disease (IBD): a spotlight on service exemplars. 2023. https://tinyurl.com/yc5cdf66 (accessed 12 February 2023) Google ScholarIBD UK. Crohn’s and colitis care in the UK: the hidden cost and a vision for change. 2021. https://tinyurl.com/35697zpj (accessed 12 February 2023) Google ScholarAbbVie. MHRA Approves RINVOQ (upadacitinib) as first oral advanced therapy to treat adults with moderately to severely active Crohn’s disease. 2023. https://tinyurl.com/2zh5zmze (accessed 12 February 2023) Google ScholarCrohn’s & Colitis UK. Understanding Crohn’s & colitis. 2023. https://tinyurl.com/4eybnjzy (accessed 12 February 2023) Google ScholarKwon YH, Banskota S, Wang H. Chronic exposure to synthetic food colorant Allura Red AC promotes susceptibility to experimental colitis via intestinal serotonin in mice. Nature Communications. 2022. https://doi.org/10.1038/s41467-022-35309-y Crossref, Google ScholarBowel Cancer UK. Ocado Retail joins our #GetOnARoll campaign. 2023. https://tinyurl.com/4sf4mkzx (accessed 12 February 2023) Google ScholarRoyal College of Nursing. Fall in nursing degree applicants exposes profession’s recruitment crisis. 2023. https://tinyurl.com/mtsrzmxb (accessed 12 February 2023) Google Scholar FiguresReferencesRelatedDetails 2 March 2023Volume 21Issue 2ISSN (print): 1479-5248ISSN (online): 2052-2835 Metrics History Published online 17 March 2023 Published in print 2 March 2023 Information© MA Healthcare LimitedPDF download

Average daily intake of artificially food color additives by school children in Saudi Arabia

Food safety is related to nutritional risk in children. This study is to determine the types of artificial food color additives (AFCAs) daily intake by school children aged 6 to 17 years for ten AFCAs. Sunset Yellow (E110), Tartrazine (E102), Carmoisine (E122), Brilliant Blue (E133), Allura Red (E129), Black PN (E151), Indigo Carmine (E132), and Fast Green (E143) were identified using 24 h food consumption questionnaire, including the two unapproved AFCAs, Red 2G (E128) and Erythrosine (E127) in 839 food products. These food products are distributed into nine categories, containing juices and drinks, ice cream, cakes, jelly, chocolates, candy, chips, biscuits, and chewing gum. Results showed that the artificial food colors, Carmoisine (32.3 %) and Sunset Yellow (30.1 %) were the most highly consumed AFCAs by school children, whereas Erythrosine (0.05 %) was consumed the least. Therefore, Sunset Yellow was highly consumed (30.1 %) and detected in high amounts by high performance liquid chromatography, (HPLC) 34.2 %. The average daily intake (ADI) of AFCAs decreased with age to varying degrees in both sexes. In comparison to the Food and Agriculture Organization and World Health Organization, acceptable daily intakes, most permitted colors exceeded their acceptable daily intakes (ADIs) in the 6–11 years of age groups, and most permitted colors were within the recommended ADIs in the 12–17 years of age group. The average daily intake of AFCAs by school children decreased with age. Therefore, further studies are required to gain information about the possible negative health effects of high intake of these AFCAs on the test population.

Genotoxicity of Synthetic Food Colors on Nitrogen-Fixing Bacteria in Agricultural Lands Irrigated with Wastewater of Corresponding Industries

Food colors are considered the most important component of foodstuff for enhancing the aesthetic appeal of the products. The rapid increase in population raised the demand for food materials, while wastewater from as-related processing industries is used for irrigation. This study was conducted to examine the genotoxicity of industrial wastewater on the plant growth-promoting rhizobacteria (PGPR). Three predominantly used synthetic food colors, including Azorubine E-122, Tartrazine E-102 and Allura Red AC E-129, were used during this project. Rhizobacteria were isolated from agricultural soils and treated with various concentrations of Azorubine E-122, Tartrazine E-102 and Allura red E-129 for a 24 and 48 h duration. DNA extraction and quantification were performed through a modified CTAB method, spectrophotometry and agarose gel electrophoresis. A comet assay was used to check DNA damage. According to the results, all the food colors had caused significant damage to DNA depending upon the concentration and exposure time. The extent of DNA damage caused by Azorubine E-122 was relatively greater compared with the other colors, so the fragmentation rate of 86% and 92% was obtained at 1.25% concentration for 24 and 48 h, respectively. The current results have revealed the devastation capacity of food colors by accelerating distortion risk to soil micro-flora, hence the fertility of the soil.

Detection of Allura Red in Food Samples Using Carbon Paste Modified with Lanthanum and Titanium Oxides

AbstractThis report describes a new electroanalytical application for the detection of Allura Red (AR) using a carbon paste electrode (CPE) modified with lanthanide oxide and titanium oxide (LaOX‐TiOX/CPE). The standard potential (Eo) for oxidation of AR was obtained from the E (V) vs. pH relation with the regression equation Ep(V)=−0.038pH+0.922, where the intercept on the axis Ep(V) is equal to the standard potential. Moreover, the anodic peak current for AR was increased almost 160 % compared to the unmodified electrodes, and this current increase allowed us to obtain a detection limit of 0.09 μmol/L. The active surface area of the modified electrode La‐TiOX/CPE is reported for the first time in this report and was increased by almost 200 % compared to the unmodified electrodes. The usefulness of the new method was tested by analyzing real food samples with acceptable results. The real samples do not need pretreatment before analysis

Nd2O3-Ag Nanostructures for Plasmonic Biosensing, Antimicrobial, and Anticancer Applications

Green synthesis of nanomaterials with multifaceted applications in photonics as well as biomedical fields has remained a daunting challenge. Engineering multielement nanohybrid libraries with synergistic surface functionalities from dielectric and metallic nanocomponents using sustainable approaches is seldom reported. In this context, we demonstrate a 1 min, user- and eco-friendly, sunlight-based green synthesis of Nd2O3-Ag, dielectric–metal ferroplasmon nanohybrids with detailed elucidation of the mechanism. Chemical anchoring of plasmonic Ag on high refractive index (n = 1.94), rare-earth Nd2O3 nanorods (average aspect ratio: ∼3) alleviates Ohmic losses without damping the plasmon resonances. Ferroplasmon-on-a-mirror (FPoM), an analogue to conventional nanoparticle-on-a-mirror (NPoM), is presented for efficient coupling of s-polarized light on account of magnetic flux modes supported by it. Apart from realization of room temperature ferromagnetism (RTFM) for nanophotonic applications, the judicious metal–nonmetal combination displayed excellent bactericidal, fungicidal, antioxidant, and anticancer properties, establishing a convergent “one health perspective” of engineered nanohybrids. Whereas the unconventional s-polarized plasmon-coupled emission obtained is utilized for sensing of food hazard Allura Red (limit of detection, LOD: 10 aM) in the FPoM platform, the p-polarized emission is used for 4-nitrophenol sensing (LOD: 100 fM). Excellent correlation between the exceptionally high Purcell factor (of 6.5 × 105 for the composite nanohybrid Nd2O3-Ag-carbon dot-graphene oxide) from simulations and experimentally obtained plasmon-coupled >2000-fold fluorescence emission enhancements is demonstrated. The utility of the proposed sunlight-induced nanoengineering to generate a library of nanocomposites comprising dielectric, metal, and graphitic plasmons is presented. We believe that the proposed methodology to generate hybrid nanomaterials with intriguing FPoM interfaces would be utilized for transdisciplinary nanophotonics as well as biomedical sensing applications.

Molecular insight into the modulation of ovalbumin fibrillation by allura red dye at acidic pH

The synthetic food additive dye induces amyloid fibrillation has many implications in the laboratory and industries. The effect of Allura red (AR), on the fibrillation of ovalbumin (Ova) at pH 2.0 was investigated. The influence of salt and pH was also seen on AR-induced Ova aggregation. We have used several spectroscopic and microscopy techniques to characterize the changes. The turbidity data suggest that concentrations above 0.05 mM of AR induce aggregation, and the size of aggregates increased in response to AR concentration. The kinetics data showed that the AR induces Ova aggregation quickly without lag time. The aggregates induced by AR have amyloid-like aggregates confirmed by far-UV CD and TEM. NaCl has very marginal effects in AR-induced aggregation. The turbidity results clearly state that Ova is not forming aggregates with pH above 4.0 due to electrostatic repulsion. However, Ova forms bigger aggregates in the presence of 0.5 mM AR at a pH below 4.0. These spectroscopic data suggest that the amyloid fibrillation that occurs in Ova is due to electrostatic and hydrophobic interaction. The amyloid fibrillation induced by AR dye in protein should be taken seriously for food safety purposes.

Managing PMT/vPvM substances in consumer products through the concepts of essential-use and functional substitution: a case-study for cosmetics.

Measures are needed to protect water sources from substances that are mobile, persistent and toxic (PMT) or very persistent and very mobile (vPvM). PMT/vPvM substances are used in a diverse range of applications, including consumer products. The combined application of the essential-use and functional substitution concepts has been proposed to phase out substances of concern and support the transition to safer and more sustainable chemicals, a key goal of the European Commission's Chemicals Strategy for Sustainability. Here, we first identified the market share of PMT/vPvM containing cosmetic products. We found that 6.4% of cosmetic products available on the European market contain PMT or vPvM substances. PMT/vPvM substances were most often found in hair care products. Based on their high occurrence, the substances Allura red (CAS 25956-17-6), benzophenone-4 (CAS 4065-45-6) and climbazole (CAS 38083-17-9) were selected as case-studies for assessment of their functionality, availability of safer alternatives and essentiality. Following the functional substitution framework, we found that the technical function of Allura red was not necessary for the performance of some cosmetic products, making the use non-essential. For other applications of Allura red, as well as all applications of benzophenone-4 and climbazole, the technical function of the chemical was considered necessary for the performance. Via the alternative's assessment procedure, which used experimental and in silico data and three different multicriteria decision analysis (MCDA) strategies, safer alternatives were identified for all case-study chemicals. All assessed uses of PMT/vPvM substances were thus deemed non-essential and should consequently be phased out.

Synthetic colourants in capsule dietary supplements on the Korean market

ABSTRACT This study developed a rapid and easy analytical method for the simultaneous determination of nine synthetic colourants (SCs) in capsule dietary supplements. Sample pretreatment involved thermal treatment to dissolve gelatin, using the enzymes protease and amylase to prevent the gelation of gelatin and fat-soluble substances removal using petroleum ether. The method was linear (r 2 ≥0.999), with LOD of 0.009–0.029 μg/mL and LOQ of 0.42–1.40 μg/g. Recovery ranged from 90.9 to 108.9%. The relative expanded measurement uncertainty ranged from 4.1 to 6.3%. Allura Red AC (R40) and Brilliant Blue FCF (B1) were commonly detected in 20 of the 28 samples. Up to six SCs such as Tartrazine (Y4), Sunset yellow (Y5), Amaranth (R2), Erythrosine B (R3), R40 and B1 were detected in a single sample, ranging from 30.5 to 40.2 μg/g. Total content of SCs in various capsule supplements ranged from 0.3 to 73.7 μg/g.

Chronic exposure to synthetic food colorant Allura Red AC promotes susceptibility to experimental colitis via intestinal serotonin in mice

Chemicals in food are widely used leading to significant human exposure. Allura Red AC (AR) is a highly common synthetic colorant; however, little is known about its impact on colitis. Here, we show chronic exposure of AR at a dose found in commonly consumed dietary products exacerbates experimental models of colitis in mice. While intermittent exposure is more akin to a typical human exposure, intermittent exposure to AR in mice for 12 weeks, does not influence susceptibility to colitis. However, exposure to AR during early life primes mice to heightened susceptibility to colitis. In addition, chronic exposure to AR induces mild colitis, which is associated with elevated colonic serotonin (5-hydroxytryptamine; 5-HT) levels and impairment of the epithelial barrier function via myosin light chain kinase (MLCK). Importantly, chronic exposure to AR does not influence colitis susceptibility in mice lacking tryptophan hydroxylase 1 (TPH1), the rate limiting enzyme for 5-HT biosynthesis. Cecal transfer of the perturbed gut microbiota by AR exposure worsens colitis severity in the recipient germ-free (GF) mice. Furthermore, chronic AR exposure elevates colonic 5-HT levels in naïve GF mice. Though it remains unknown whether AR has similar effects in humans, our study reveals that chronic long-term exposure to a common synthetic colorant promotes experimental colitis via colonic 5-HT in gut microbiota-dependent and -independent pathway in mice.

Spectroscopic and molecular docking studies of the interactions of sunset yellow and allura red with human serum albumin

AbstractBinding interactions of human serum albumin (HSA) with sunset yellow (SY) and allura red (AR), two food colorants, were investigated at the molecular level through fluorescence and UV absorption as well as molecular docking. The collective results of the study under the simulated physiological conditions proposed a static type of binding occurring between the two dyes and HSA. When compared with AR (293 K: Ksv = (4.21 ± 0.36) × 104 L·mol−1; Kb = (0.30 ± 0.23) × 106 L·mol−1), SY (293 K: Ksv = (6.80 ± 0.10) × 104 L·mol−1; Kb = (3.11 ± 2.01) × 106 L·mol−1) had stronger quenching ability and higher affinity for HSA due to less steric hindrance. It can be deduced that the energy transfer from HSA to the two dyes occurred with high probability based on the Förster resonance energy transfer theory (r &lt; 7 nm, 0.5 R0 &lt; r &lt; 2.0 R0). The spectral analysis suggested that the formation of the dye‐HSA complex resulted in the change in microenvironment around Tyr and Trp residues and in the secondary structure of the protein. According to molecular docking simulation, the two structural analogs almost bound to the same site of HSA, near Sudlow's Site I, but significant difference existed in the number and location of hydrogen bond (H‐bond) formed between the dyes and HSA. From the molecular docking along with the thermodynamic parameters (AR: ΔHo = −(58.79 ± 15.24) kJ·mol−1, ΔSo = −(115.1 ± 31.10) J·mol−1·K−1; SY: ΔHo = −(52.24 ± 3.15) kJ·mol−1, ΔSo = −(50.07 ± 11.14) J·mol−1·K−1), it could be inferred that H‐bond and van der Waals forces were the major binding forces involved in formation of the dye‐HSA complexes.

Colorimetry Combined with Inner Filter Effect-Based Fluorometry: A Versatile and Robust Strategy for Multimode Visualization of Food Dyes

Herein, a strategy combining colorimetry and inner filter effect (IFE)-based fluorometry was developed for multimode visualization of food dyes (FDs) using CdTe quantum-dots-doped fluorescent indicator papers as a sample-to-answer device. Colorimetry was straightforwardly achieved by FDs extraction through electrostatic interaction and hydrophobic effect while fluorometry was implemented by IFE-induced fluorescence quenching. RGB/gray-scale values of colorimetry and fluorometry were furtherly picked by a smartphone application and applied to reconstruct color information-based digital image analysis for both direct alignments and linear regression analysis. The apparent color and fluorescence of FDs-bound indicator papers, together with their digitized color information, showed a good mapping to FDs concentrations in the range of 0-0.5 mg/mL for Sunset Yellow, 0-0.2 mg/mL for Allura Red, and 0-0.08 mg/mL for Brilliant Blue. As a proof of concept, the dosages of these FDs in real beverages and simulated dye effluents were deduced and cross-validated by different visualization modes, and finally double-checked by instrumental techniques such as spectrometric methods, high-performance liquid chromatography (HPLC), and mass spectroscopy (MS). The above findings concluded that (i) IFE mechanism is generally applicable to build fluorometric systems and (ii) cross validation of different visualization modes can markedly improve detection accuracy, which may provide references for design and fabrication of novel "lab-on-paper" devices for visualization applications with high reliability.

Polyphenylalanine ionic liquid for the extraction and determination of Allura red in food samples

AbstractPoly amino acids ionic liquid {3‐(3‐(7‐(diethylamino)‐2‐carbonyl‐2 h‐amino‐3‐propyl)‐1‐ethyl Bromo imidazole P[Phe][EMI]} was synthesized and characterized with Fourier transform infrared spectroscopy (FTIR), hydrogen nuclear magnetic resonance (1H‐NMR), and scanning electron microscopy (SEM). A novel method based on solid‐phase extraction and high‐performance liquid chromatography for the detection of Allura red (AR) was established. Under optimized conditions, the linear range of AR was 0.01–10.00 μg ml−1, the limit of detection (LOD) was 0.004 μg ml−1 and the enrichment factor was 12.5 (volume of solution/volume of elution). The isothermal adsorption, kinetic model, and Gaussian calculation model was explained by the adsorption mechanism of AR on P[Phe][EMI]. The method was applied to the analysis of real samples with recoveries of 92.0%–102.2% and relative standard deviations of 1.0%–4.6%.

TO THE PROBLEM ON THE OXIDATION MECHANISM OF AZO DYES ON MODIFIED CARBON-PASTE ELECTRODES

In the current study, using a carbon-paste electrode modified with β-cyclodextrin oligosaccharide, the oxidation mechanism of some useful food azo dyes as Sunset Yellow FCF, Tartrazine, Allura Red AC, Carmoisine, Ponceau 4R was established. Cyclic voltammetry was used to investigation redox behaviour of studied food azo dyes (Sunset Yellow FCF, Tartrazine, Allura Red AC, Carmoisine, Ponceau 4R). It was established that such dyes as Sunset Yellow FCF and Ponceau 4R are oxidized quasi-reversibly, and such as Tartrazine, Carmoisine and Allura Red AC are completely irreversibly oxidized. It was noted that for all dyes, except Tartrazine, after oxidation on a cyclic voltammogram, a new reversibly redox pair is formed. This may indicate the formation of new electroactive fragments during the oxidation of azo dyes (Sunset Yellow FCF, Allura Red AC, Carmoisine, Ponceau 4R). Based on the conducted studies of the effect of pH and scanning rate on the oxidation potential of studied azo dyes, it was established that 2 electrons and 1 proton participate in the oxidation process for all dyes, except for Carmoisine, for which oxidation takes place with the participation of 1 proton and 1 electron. Based on the obtained information, as well as using information from our previous studies on the redox behavior of azo dyes (Sunset Yellow FCF, Tartrazine, Allura Red AC, Carmoisine, Ponceau 4R) on carbon-paste electrode modified by silica impregnated with cetylpyridinium chloride cationic surfactant, a scheme for the oxidation of azo dyes was proposed. According to the scheme, oxidation takes place with the participation of an irreversible chemical reaction, which leads to the further rearrangement of bonds with the breaking of the azo group of dyes and the formation of new electroactive fragments.