Determination of synthetic and natural colorants in selected green colored foodstuffs through reverse phase-high performance liquid chromatography

Ratiometric fluorescence and smartphone-assisted sensing platform based on dual-emission carbon dots for brilliant blue detection

In this study, an innovative ratiometric fluorescence and smartphone-assisted visual sensing platform based on blue-yellow dual-emission carbon dots (BY-CDs) was constructed for the first time to determine brilliant blue. The BY-CDs was synthesized via a facile one-step hydrothermal process involving propyl gallate and o-phenylenediamine. The synthesized BY-CDs exhibit favorable water solubility and exceptional fluorescence stability. Under excitation at 370 nm, BY-CDs show two distinguishable fluorescence emission bands (458 and 558 nm). Upon addition of brilliant blue, the fluorescence intensity at 558 nm exhibited a significant quenching effect attributed to fluorescence resonance energy transfer (FRET), while the fluorescence intensity at 458 nm was basically unchanged. The prepared BY-CDs can effectively serve as a ratiometric nanosensor for determining brilliant blue with the ratio of fluorescence intensities at 458 and 558 nm (F458/F558) as response signal. In addition, the developed ratiometric fluorescence sensor exhibits a noticeable alteration in color from yellow to green under UV light with a wavelength of 365 nm upon addition of varying concentrations of brilliant blue, which provides the possibility of visual detection of brilliant blue by a smartphone application. Finally, the BY-CDs based dual-mode sensing platform successfully detected brilliant blue in actual food samples and achieved a desirable recovery rate. This study highlights the merits of fast, convenient, economical, real-time, visual, high accuracy, excellent precision, good selectivity and high sensitivity for brilliant blue detection, and paves new paths for the monitoring of brilliant blue in real samples.

Simultaneous determination of 11 water-soluble synthetic colorants in foods consumed in Chile by high-performance liquid chromatography with diode Array detection

In Chile, limited information is available on colorants in commonly consumed foods among vulnerable age groups. We developed and validated a rapid HPLC-DAD method to simultaneously evaluate 11 synthetic colorants in candies, beverages, ice cream, and cereals. The method exhibited excellent analytical performance for all 11 colorants with LOD (0.44 - 1.55 mgL-1), LOQ v(1.32 - 4.70 mgL-1), precision (4.0 and 7.3% RSD), and recovery (80 - 105%) in fortified matrices (10-50-100 mgL-1). The highest detection frequencies were as follows: cereals > candies > beverages > ice cream. Sunset Yellow was the most prevalent colorant in all food matrices, followed by Allura Red and Azorubine. Positive samples contained between 1 and 5 synthetic colorants. With the exception of cereals, the colorant concentrations in the remaining matrices exceeded the Codex Alimentarius regulations and the values reported in other studies worldwide, indicating the Chilean population is at risk.

An update on the sample preparation and analytical methods for synthetic food colorants in food products

Colorants, especially synthetic colorants, play a crucial role in enhancing the aesthetic qualities of food owing to their cost-effectiveness and stability against environmental factors. Ensuring the safe and regulated use of colorants is essential for maintaining consumer trust in food safety. Various preparation and analytical technologies, which are continuously undergoing improvement, are currently used to quantify of synthetic colorants in food products. This paper reviews recent developments in analytical techniques for synthetic food colorants, detection and compares the operational principles, advantages, and disadvantages of each technology. Additionally, it also explores advancements in these technologies, discussing several invaluable tools of analysis, such as high-performance liquid chromatography, liquid chromatography-tandem mass spectrometry, electrochemical sensors, digital image analysis, near-infrared spectroscopy, and surface-enhanced Raman spectroscopy. This comprehensive overview aims to provide valuable insights into current progress and research in the field of food colorant analysis.

Dauricine: Review of Pharmacological Activity

Background

Dauricine is an important natural organic compound in Menispermum dauricum, which often has significant biological activity.

Purpose

The purpose of this review is to systemically summarize and discuss the pharmacological activity and underlying mechanisms of dauricine in recent years.

Methods

Web of Science (121 articles) and PubMed databases (97 articles) were used to search for articles related to "dauricine" published from 2000 to 2024. Meanwhile, we classified the pharmacological activity of dauricine by screening these articles.

Results

Emerging evidence suggests that dauricine possesses numerous pharmacological activities, including neuroprotection, anti-cancer, anti-arrhythmia, anti-inflammatory and anti-diabetes.

Conclusion

Dauricine has a potential value in the treatment of many diseases. We hope that this review will contribute to therapeutic development and future studies of dauricine.

Hepato-renal protective impact of nanocapsulated Petroselinum crispum and Anethum graveolens essential oils added in fermented milk against some food additives via antioxidant and anti-inflammatory effects: In silico and in vivo studies

The study assessed the efficacy of parsley and dill essential oils (EOs) nanocapsules incorporated into fermented milk in hepato-renal protection against specific food additives. A molecular docking assay was conducted between parsley and dill EOs bioactive molecules and inflammatory cytokines. Freeze-dried parsley and dill EOs nanocapsules were developed, characterized for their morphological structure, particle size, zeta potential, polydispersity index and encapsulation efficiency and assessed in fast green dye and sodium benzoate (SB) combination-treated rats. The docking results revealed that the primary constituents of parsley and dill EOs (apiol, myristicin, α-pinene, (-)-carvone, and d-limonene) interacted with the active sites of TNF-α, IL-1β and TGF-1β cytokines with hydrophobic and hydrogen bond interactions. D-limonene had the highest binding affinity (6.4 kcal/mol) for the TNF-α. Apiol and myristicin had the highest binding affinity (5.1, 5.0, 5.0 and 5.0 kcal/mol, respectively) for the IL-1β and TGF-β1 receptors. Biochemically and histopathologically, the excessive co-administration of fast green and SB revealed adverse effects on the liver and the kidney. Whereas the treatment with parsley and dill EOs nanocapsules afford hepato-renal protective effects as manifested by suppression the elevated liver and kidney functions. Parsley and dill EOs nanocapsules showed a significant reduction of the liver (64.08 and 80.5 pg/g, respectively) and kidney (59.3 and 83.6 pg/g, respectively) ROS. Moreover, parsley and dill EOs nanocapsules down-regulated the liver and the kidney inflammatory cytokines (IL-6, TNF-α, IL-1β and TGF-1β) and lipid peroxidation and up-regulated the antioxidant enzymes. In conclusion, the data suggest a potential hepato-renal protective effects of parsley and dill EOs nanocapsules.

Multiplexed colorimetry collaborated with smartphone-based image analysis for simultaneous and fast visualization of dyes in both environmental and food samples

In this work, a multiplexed colorimetric strategy was initiated for simultaneous and fast visualization of dyes using low-cost and easy-to-prepare indicator papers as sorbents. Response surface methodology (RSM) was employed to model statistically and optimize the process variables for dyes extraction and colorimetric assays. Multiplexed colorimetry was realized by virtue of synchronous color alignments from different dimensions of multiple dyes co-stained colorimetric cards under RSM-optimized conditions, and smartphone-based image analysis was subsequently performed from different modes to double-check the credibility of colorimetric assays. As concept-to-proof trials, simultaneous visualization of dyes in both beverages and simulated dye effluents was experimentally proved with results highly matched to HPLC or spiked amounts at RSM-predicted staining time as short as 50 s ∼3 min, giving LODs as low as 0.97 ± 0.22/0.18 ± 0.08 μg/mL (tartrazine/brilliant blue) for multiplexed colorimetry, which much lower than those obtained by single colorimetry. Since this is the first case to propose such a RSM-guided multiplexed colorimetric concept, it will provide a reference for engineering of other all-in-one devices which can realize synchronous visualization applications within limited experimental steps.

Revealing the variances in color formation and bioactivities of seven catechin monomers throughout the enzymatic reaction by colorimetric and mass spectrometry

The capacity differences of seven catechin monomers to produce colors after treating with catechin-free extract were investigated. After 240-min reaction, only (-)-epicatechin (EC) and (+)-catechin (C) presented obvious luminous red color with L* values of 63.32-71.73, a* values of 37.13-46.44, and b* values of 65.64-69.99. Meanwhile, the decrease rate of EC and C was 43.52 %-50.35 %, which were significantly lower than those of other catechin monomers (85.91 %-100 %). The oxidized products of catechin monomers were analyzed by ultra-high performance liquid chromatography-quadrupole-time of flight-mass spectrometry coupled with diode array detector, wherein dehydro-dimers and -trimers (oxidative coupling products of catechins' A-B ring) were found to be the major chromogenic compounds of EC and C. Additionally, the antioxidant capacity of catechin monomers only decreased after 30-min reaction, while along with further enzymatic reaction, catechin monomers presented comparable oxyradical scavenging ability (e.g., the DPPH inhibitory rates of catechin monomers were in the range of 24.42 %-50.77 %) to vitamin C (positive control, DPPH inhibitory rate was 27.66 %). Meanwhile, the inhibitory effects of most catechin monomers on α-glucosidase were enhanced in different degrees. These results provided basis for the development of enzymatically-oxidized catechin monomers as functional food color additives.

Absolute chlorophyll composition of commercial green food colorants and coloring foodstuff by HPLC-ESI-QTOF-MS/MS: Copper chlorophyllins

Sodium copper chlorophyllins (SCC) are used worldwide to brightly color green foods as authorized food colorants, although their composition is only partially known. This study applied a combination of experimental and in silico techniques to describe the SCC profile in commercial colorant products and coloring foods. Different approaches have allowed identifying five new chlorophyll compounds in the food colorants besides the description of unique product ions able to distinguish among different chlorophyll isomers for the first time. In addition, a detailed isotope cluster analysis has revealed the formation of two new structures of copper chlorophyllins, featuring the copper in peripheral positions instead of the central pocket. Finally, a computational study of thermodynamic parameters and molecular descriptors has determined the factors responsible for the formation of the two main copper chlorophyllins present in the food colorants. This information will sustain alternative processing leading to SCC products with tailored composition.

Differences in the Chromogenic Effect of Corn Starch and Potato Starch on Paprika Red Pigment and Structural Characterisation

The present study aims to investigate the chromogenic effect and the interaction between starch-pigment complexes of corn starch (CS) and potato starch (PS) complexed with paprika red pigment. Compared to PS, CS showed 12.5 times higher adsorption capacity for paprika red pigment. Additionally, the a* value of CS-P (26.90 ± 0.23) was significantly higher than that of PS-P (22.45 ± 1.84), resulting in a corn starch-paprika red pigment complex (CS-P) with a more intense red colour. The addition of paprika red pigment significantly decreased the particle size and porosity of CS by 48.14 ± 5.29% and 17.01 ± 3.80%, respectively. Conversely, no significant impact on PS was observed. Additionally, the Fourier transform infrared (FT-IR) spectroscopy results revealed that the starch molecules and paprika red pigment were bound to each other through strong hydrogen bonds. X-diffraction (XRD) results indicated that the starch-paprika red pigment complexes have a V-shaped structure. Furthermore, the relative crystallinity of the complexes between starch and red pepper pigment showed an increasing trend, however, the relative crystallinity of CS increased significantly by 11.77 ± 0.99-49.21 ± 3.67%. Consequently, the CS-P colouring was good.

Study of the authentic composition of the novel green foods: Food colorants and coloring foods

The clean label approach is behind the development of the new concept, coloring food, in contrast to regulated food colorants, although few data are available regarding its composition. Consequently, twenty-six commercial green foods (including novel foods) have been analyzed to investigate the authentic composition behind the different labels. It has been identified by HPLC-ESI/APCI-hrTOF-MS2 the complete array of chlorophylls in the regulated green food colorants, several of them identified for the first time in foods. The coloring food alternative is based on mixing blue (such as spirulina) and yellow (such as safflower) hues. Our data suggest that in the analyzed samples, spirulina is water or solvent extracted before being added to the food. The obtained results showed for the first time, the authentic data on the chemical composition of the new green foods.

Analysis of Chlorophylls/Chlorophyllins in Food Products Using HPLC and HPLC-MS Methods

Of the different quality parameters of any food commodity or beverage, color is the most important, attractive and choice-affecting sensory factor to consumers and customers. Nowadays, food industries are interested in making the appearance of their food products attractive and interesting in order to appeal to consumers/customers. Natural green colorants have been accepted universally due to their natural appeal as well as their nontoxic nature to consumers. In addition, several food safety issues mean that natural green colorants are preferable to synthetic food colorants, which are mostly unsafe to the consumers but are less costly, more stable, and create more attractive color hues in food processing. Natural colorants are prone to degradation into numerous fragments during food processing, and thereafter, in storage. Although different hyphenated techniques (especially high-performance liquid chromatography (HPLC), LC-MS/HRMS, and LC/MS-MS are extensively used to characterize all these degradants and fragments, some of them are not responsive to any of these techniques, and some substituents in the tetrapyrrole skeleton are insensitive to these characterization tools. Such circumstances warrant an alternative tool to characterize them accurately for risk assessment and legislation purposes. This review summarizes the different degradants of chlorophylls and chlorophyllins under different conditions, their separation and identification using various hyphenated techniques, national legislation regarding them, and the challenges involved in their analysis. Finally, this review proposes that a non-targeted analysis method that combines HPLC and HR-MS assisted by powerful software tools and a large database could be an effective tool to analyze all possible chlorophyll and chlorophyllin-based colorants and degradants in food products in the future.

Dual emission N-doped carbon dots as a ratiometric fluorescent and colorimetric dual-signal probe for indigo carmine detection

Novel dual-emission fluorescent nitrogen-doped carbon dots (N-CDs) were synthesized by a facile one-pot hydrothermal method using ascorbic acid and rhodamine B as precursors and melamine as nitrogen source. The obtained N-CDs exhibited dual-emitting peaks at 435 nm and 578 nm under the single excitation of 350 nm. The fluorescence at 578 nm was more effectively quenched by indigo carmine (IC) based on the internal filtration effect and aggregation-induced emission quenching. Meanwhile, the apparent color change of N-CDs from pink to blue-purple after adding various concentrations of IC could be clearly observed with the naked eye. Therefore, a ratiometric fluorescent and colorimetric dual-signal probe based on N-CDs was developed for IC detection with high selectivity and sensitivity. The addition of IC caused the ratiometric fluorescent value (F₄₃₅/F₅₇₈) to increase linearly within the range from 0 to100 µM with a detection limit (LOD) of 0.18 µM and the colorimetric signal presented a linear response in the range of 0-133 µM with a LOD of 57.4 nM. Furthermore, the IC in juice drink, candy, and water was successfully detected. Besides, the N-CDs were also designed as a ratiometric temperature probe, and the ratiometric fluorescence signal (F₄₃₅/F₅₇₈) was linearly and reversibly responsive to temperature in the range of 20-75 °C.

Combination of colorimetry, inner filter effect-induced fluorometry and smartphone‑based digital image analysis: A versatile and reliable strategy for multi-mode visualization of food dyes

Herein, a multi-mode visualization platform was initiated for in-situ detection of food dyes (FDs) by combining colorimetry, fluorometry and smartphone‑based digital image analysis, in which water-dispersible quantum dots (QDs) were served as nanoprobes. Colorimetry was achieved by color comparison, while both fluorometry and fluorescence quantification were performed through inner filter effect (IFE)-induced fluorescence quenching, then color information (RGB & gray-scale values) of colorimetry and fluorometry was picked by a smartphone to reconstruct digitized alignments. Since IFE mechanism was concentration-dependent but did not rely on the interaction between fluorophore and quencher, the whole process of fluorescence response could be finished within 10 s, and both color gradients and fluorescence changes showed fine mappings to FDs concentrations in the range of 1.0 × 10^-3∼0.035 mg/mL for brilliant blue, and 1.0 × 10^-4∼0.1 mg/mL for Allura red and sunset yellow. As a proof-of-concept, the in-situ multi-mode visualization of these FDs in real beverages was experimentally proved to be highly feasible and reliable as compared with instrumental techniques like UV-vis/fluorescence spectrometry, along with HPLC. Finally, this strategy was extended to the multi-mode visualization of non-food dyes in three simulated wastewater samples with high credibility by contrast with the true additive amounts of model dyes.

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.

Selective and sensitive detection of tartrazine in beverages by sulfur quantum dots with high fluorescence quantum yield

In this work, sulfur quantum dots (TPA-SQDs) protected by terephthalic acid as a stabilizer were synthesized using a one-pot method. When excited at 310 nm, the synthesized TPA-SQDs solution emitted strong blue fluorescence at 428 nm, and the absolute quantum yield was as high as 85.99%. The proposed SQDs can be used as a fluorescent probe to specifically quench tartrazine (TZ), showing a good linear relationship (R² = 0.996) at TZ concentrations of 0.1-20 μM, with a detection limit of 39 nM. By analysing the fluorescence lifetime, UV-Vis absorption spectrum and zeta potential of the assay system, it can be speculated that the fluorescence quenching mechanism of TZ on TPA-SQDs is the inner filter effect (IFE). The proposed method was applied to the detection of TZ in vitamin water and orange juice, and the results were consistent with the determination results by high-performance liquid chromatography. The recoveries and relative standard deviations were 93.2-102.6% and 1.34-2.88%, respectively, which provided an alternative method for the determination of TZ in beverages or other food samples.

Fast Sensitive and Accurate Analysis of the Most Common Synthetic Food Colorants in 65 Egyptian Commercial Products Using New HPLC–DAD and UPLC-ESI–MS/MS Methods

Overexposure to food colorants above the allowed daily intake (ADI) level can provoke hyperactivity and other disturbed behaviors especially in children. Two new methods were developed to separate five synthetic colorants, which were Tartrazine (E102), Sunset Yellow (E110), Allura Red (E129), Carmoisine (E122), and Brilliant Blue (E133). They are labeled on a large variety of commercial food products in the Egyptian market without mentioning their definite concentrations. Therefore, there was a real need to determine these colorants with simple, accurate, and fast methods. This is the first study to determine these colorants in a wide variety of food products present in the Egyptian market. The HPLC approach with photodiode array detection was developed to quantify these colorants, on a C18 column, with a mobile phase composed of acetonitrile and water containing 1% ammonium acetate (pH 6.8), separation was carried out using a gradient program. The colorants were eluted and efficiently separated within 9 min. Then, as a complementary technique to HPLC, the UPLC-ESI–MS/MS approach was developed for identification and accurate mass measurement of the colorants found in high concentrations, the colorants were obtained simultaneously in negative mode, the run time was only 3 min. These developed methods were validated according to ICH recommendations and they were applied to analyze 65 food products including jelly powder, puddings, ice cream powders, concentrated soft drink powders, carbonated drinks, chewing gums, and sugar confectionery.

A surfactant-mediated microextraction of synthetic dyes from solid-phase food samples into the primary amine-based supramolecular solvent

An effective and simple surfactant-mediated microextraction of synthetic dyes from solid-phase food samples into the primary amine-based supramolecular solvents is presented for the first time. The developed procedure involved two stages: (i) an isolation of dyes from a solid-phase food sample into a micellar solution of the primary amine; (ii) a preconcentration of the extracted dyes into the supramolecular solvent phase generated from the obtained micellar solution under a coacervation process. The microextraction procedure was applied for the determination of synthetic dyes in confectionery, dried fruits, and spices samples. The supramolecular solvent formed from aqueous micelle aggregates of 1-octylamine due to coacervation induced by thymol provided maximum extraction recovery values for synthetic dyes. In the proposed two-stage extraction procedure the micellar solution of primary amine was a media for analytes isolation from solid-phase and their followed preconcentration.

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.

Magnetic Solid-Phase Extraction Based on Magnetic Sulfonated Reduced Graphene Oxide for HPLC-MS/MS Analysis of Illegal Basic Dyes in Foods

In this study, a magnetic solid-phase extraction (MSPE) method coupled with High-Performance Liquid Chromatography Mass Spectrometry (HPLC–MS/MS) for the determination of illegal basic dyes in food samples was developed and validated. This method was based on Magnetic sulfonated reduced graphene oxide (M-S-RGO), which was sensitive and selective to analytes with structure of multiaromatic rings and negatively charged ions. Several factors affecting MSPE efficiency such as pH and adsorption time were optimized. Under the optimum conditions, the calibration curves exhibited good linearity, ranging from 5 to 60 µg/g with correlation coefficients >0.9950. The limits of detection of 16 basic dyes were in the range of 0.01–0.2 µg/L. The recoveries ranged from 70% to 110% with RSD% < 10%. The results indicate that M-S-RGO is an efficient and selective adsorbent for the extraction and cleanup of basic dyes. Due to the MSPE procedures, matrix effect and interference were eliminated in the analysis of HPLC–MS/MS without the matrix-matched standards. Thus, validation data showed that the proposed MSPE–HPLC–MS/MS method was rapid, efficient, selective, and sensitive for the determination of illegal basic dyes in foods.

[Determination of new carmine in beverages by one step rapid solid phase extraction based on metal organic framework extractant]

New coccine is an azo pigment that is widely used in food. To mitigate potential health issues arising from excessive consumption, China has issued provisions on the allowed addition limit of new coccine in food. Currently, there are certain difficulties with establishing detection methods for such trace pigments in foods; for example, preprocessing is complex and time-intensive. In addition, the low content of the target substance in the sample could be disturbed by food matrix, resulting in poor detection sensitivity. Metal organic frameworks (MOFs), as a novel class of highly efficient adsorbents, have attracted increasing attention because of their stability and large specific surface area. MOFs are porous coordination crystal structures that connect metal clusters with organic ligands via coordination. Owing to their molecule-sized pores, MOFs can be used in various fields such as adsorption, catalysis, and drug dispersion. However, at the same time, their ultra-high specific surface area also leads to ultra-low weight of the material itself; this makes it difficult to collect the material even under high-speed centrifugation. In this study, a MOF material (PCN-222) with a high specific surface area was prepared by the coordination of the carboxyl group in the porphyrin ring and metal zirconium ions. To simplify pretreatment, the nanomaterials were filled into an injection solid phase extraction device for the rapid extraction of new coccine pigments from beverages. The morphology, structure, and properties of the PCN-222 nanomaterials were studied by transmission electron microscopy, particle size analysis, X-ray single-crystal diffraction, infrared spectroscopy, and ultraviolet spectroscopy. The specific surface area of the synthesized material was 979 m2/g. A high specific surface area was conducive to the adsorption of trace target compounds. The surface charge of the material could be controlled by adjusting the pH value of the solution, which was beneficial to the selective adsorption and desorption of ionic pigments. The π-π interaction between the benzene ring of the porphyrin ring and the benzene ring of the azo pigment also promoted extraction. Thus, the extractant exhibited strong enrichment performance for the new coccine anionic pigment. The solid phase extraction conditions were optimized, and it was found that saturated adsorption capacity was achieved by filling 3 mg of extractant. The effect of pH on adsorption was also explored; the adsorption effect was the best at pH 3. In the desorption experiment, N,N-dimethylformamide at pH 11 was conducive to better elution of the target. Further elution volume studies showed that maximum recovery could be achieved by adding 3 mL of eluent. Subsequently, the sample pretreatment time was reduced to 5 min. The enriched sample was separated using a Zorbax eclipse XDB-C18 column (250 mm×4.6 mm, 5 μm), eluted with an ammonium acetate-methanol solvent system, and detected at 254 nm. Under the optimum conditions, the recoveries of the samples at high, medium, and low levels reached 99.5%-109.4%, and the relative standard deviation was less than 3%. The limit of detection (LOD, S/N=3) of this method was 0.1 μg/L and the limit of quantification (LOQ, S/N=10) was 0.3 μg/L. In the actual sample detection experiment, the detection signal of new coccine in the sample was amplified by solid phase extraction to achieve enrichment. In addition, the extraction capacity of PCN-222 remained higher than 90% after four uses, and the synthesized material could be recycled. The high precision and low detection limit indicate that the method is suitable for the enrichment and detection of trace carmine in beverages. The findings of this study will aid in the development of a new solid phase extraction technology for food safety evaluation.

Quantification of permitted synthetic colours in food by liquid chromatographic methods: a review on analytical methods and their performance

Colours, natural and synthetic, are substances which add or restore colour to a food after processing or storage. They are widely used by food manufacturers but may pose a potential risk to human health. Most food safety authorities set up regulations to limit the use of synthetic colours, and monitor their levels and consumption by the general public. Therefore, validated analytical methods are needed to fulfil this requirement. This review presents a comprehensive overview of various liquid chromatographic methods used for quantification of permitted synthetic colours in foods. Available analytical methods have been assessed for their fitness for purpose in terms of extraction, clean-up, liquid chromatographic separation, quantification and method performance. The advantages and disadvantages are given of available analytical methods for analysing 24 synthetic colours, permitted for use by different jurisdictions. Gaps in the knowledge and levels of validation are identified and recommendations made on further research to develop suitable methods for routine monitoring of these permitted synthetic colours.

Qualitative screening and quantitative determination of multiclass water-soluble synthetic dyes in foodstuffs by liquid chromatography coupled to quadrupole Orbitrap mass spectrometry

A LC-Q-Orbitrap HRMS analytical method for both qualitative screening and quantitative determination of 90 synthetic dyes including ten groups of isomers in foods has been established. An in-house synthetic dyes database and characteristic ions were also developed. Based on Q-Orbitrap HRMS, mass spectrum and fragmentation patterns of synthetic dyes were studied, which indicated that double charged ions were usually the main precursor ions. Matrix effects were successfully eliminated by the C₁₈ d-SPE clean-up coupled with dilute and shoot approach with methanol-water (1:4, v/v) in 100-fold. For most of the compounds, mean recoveries were satisfactory between 70% and 120% with RSD < 20% at three spiked level in the range of 0.025-1.0 mg/kg. The screening detection limits ranged from 0.025 - 1.0 mg/kg. Method validation showed that the established method was efficient, rapid and high-throughput, which has been successfully applied to the monitoring of these water-soluble synthetic dyes in foods.

On the Suitability of Almond Shells for the Manufacture of a Natural Low-Cost Bioadsorbent to Remove Brilliant Green: Kinetics and Equilibrium Isotherms Study

Almond production generates a large number of coproducts, but the farmer's interest mainly focuses on the nutritional and commercial aspects of the kernel for getting the best return from their harvests. Thus, almond coproducts such as almond shells that represent more than 70% of biomass remain underexplored. In this work, the suitability of almond shell powder (ASP) as a natural low-cost adsorbent was evaluated in the adsorption of brilliant green dye (BG), which is known as a chemical pollutant. Brunauer-Emmett-Teller (BET) method, for the determination of specific surface area, Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) techniques were performed to characterize the ASP adsorbent. The batch adsorption kinetic study for the removal of BG dye was carried out by varying pH, temperature, initial concentration of the dye, bioadsorbent dose, and contact time. It was found that 98% of BG dye is removed under the following optimal experimental conditions: ASP bioadsorbent dose of 1 g/L at T = 25°C, pH = 6.8, and C 0 = 1 g/L, which proves that ASP can be used as an excellent low-cost bioadsorbent for the removal of BG dye from wastewater. The experimental isotherm data were analyzed using Freundlich and Langmuir models. The results show the best correlation with single-layer adsorption, and the adsorption kinetics seems to follow a pseudo-second-order model.

Rapid determination of seven synthetic dyes in casual snacks based on packed-fibers solid-phase extraction coupled with HPLC-DAD

Based on packed-fiber solid-phase extraction and HPLC-DAD, a simple analytical method for the determination of seven synthetic dyes has been successfully developed. Polystyrene/polypyrrole (PS/PPy) fibers were obtained via electro-spinning of polystyrene skeletal nanofibers, followed by the oxidation with FeCl₃ to trigger the polymerization of pyrrole and the deposition of polypyrrole coatings on PS fibrous skeleton fibers. The relationship between the extraction performance of the fibers and the electrospinning process at different humidities was investigated based on morphologic study and BET surface area. In the extraction process, purification, concentration, and desorption could be accomplished in one step. The established method exhibited good sensitivity, selectivity, reproducibility, and good efficiency for synthetic dyes in casual snacks (preserved fruit, flavored yogurt, and fruity hard candy) samples. With optimal conditions, the LODs (S/N = 3) were 2.4 to 21.09 ng mL^-1, and linearities were acceptable in liquid matrix and solid matrices. The recoveries were 93.9-103.9%.

Development of an accurate and direct method for the green food colorants detection

Color impression represents between 60 and 90% of the final acceptance/rejection choice made by consumers. Consequently, color additives are attribute standards for our daily life in any market and any culture. Currently, authorized natural green food colorants comprise several copper-chelated chlorophyll derivatives. Both the raw materials and the manufacturing processes for the acquisition of these green food colorants are numerous and diverse. Hence, each producer applies its own know-how to obtain 'signature' green colorant products. Indeed, the chlorophyll profile of these products is partially known and may substantially differ among batches, while their identification just by HPLC-UV-Vis is not complete. Native chlorophylls do not chelate copper. Therefore, we propose a fast and specific method for copper chlorophyll detection, as indicative (except in a few fermented foods) of probable green food colorant addition or "re-greening" with copper salts. The new method is based on the characteristic isotopic pattern of the copper chlorophyll derivatives and does not require the precise characterization of the corresponding chlorophyll structure. This accurate methodology, based on a specific HPLC-ESI/APCI-HRMS method assisted with powerful post-processing software, is versatile as it can be used for other metallo-chlorophyll complexes also applied to improve the green coloration of food products.

A phenylenediamine-based carbon dot-modified silica stationary phase for hydrophilic interaction chromatography

Red emitting carbon dots derived from p-phenylenediamine were successfully grafted onto the surface of porous silica spheres which served as a new stationary phase for hydrophilic interaction chromatography with enhanced selectivity.

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