Fast chromatographic method for the determination of dyes in beverages by using high performance liquid chromatography—Diode array detection data and second order algorithms

A fluorescent sensor based on sulfur nanodots encapsulated into zeolitic imidazolate framework-8 for ultrasensitive detection of tartrazine

A new composite material (SDs@ZIF-8) was synthesized by integrating sulfur nanodots (SDs) into metal-organic frameworks (ZIF-8) through a facile one-step self-assembly strategy. The obtained SDs@ZIF-8 has not only the high adsorption performance of ZIF-8 but also the superior fluorescence characteristics of SDs. The composite featured good dispersibility, stable structure as well as excellent fluorescence in water solution, and can be used as an ideal fluorescent sensor for tartrazine detection. Due to the high specific surface area and adsorption performance of ZIF-8, the prepared composite material can significantly enrich tartrazine, further enhancing the sensitivity of analysis. The fluorescence of SDs @ZIF-8 composite can be effectively quenched by tartrazine through the inner filter effect. The sensing technique exhibited exceptional sensitivity, as evidenced by its impressive detection limit of 6.5 nM across a broad linear range spanning from 0.02 to 90 μM. In addition to its high sensitivity, the technique displayed rapid response times and excellent selectivity. Moreover, the fluorescent sensing technology we developed has been employed successfully for the detection of tartrazine in real samples, which is expected to promote the development of the food safety industry.

Separation and determination of basic orange II, acid orange II and auramine O in soybean products based on ionic liquid reverse micelle microextraction and ultra-high-performance liquid chromatography

A new analytical method was developed for the separation and determination of basic orange II, acid orange II and auramine O in soybean products. The technique was focused on ionic liquid reverse micelle microextraction (IL-RMME) followed by analysis and determination by ultra-high performance liquid chromatography (UHPLC) with photodiode array detector of three chemical dyes. In this method, IL-RMME solution consisting of ionic liquid [Omim]BF6 and surfactant GenapolX-080 was used as extractant. Important parameters affecting IL-RMME efficiency, such as extraction solvent type and volume, sample solution pH, salt effect, centrifugation speed and time were investigated. Under the optimal condition, the linearity of the method was in the range of 0.1-10 ng mL-1with correlation coefficient above 0.9994 and the limits of detection below 0.03 ng mL-1. At the same time, relative standard deviations of the developed procedure for intra- (n = 5) and inter-day (n = 5) precision were in the range of 5.04-8.50%. The results demonstrated that a simple fast environmentally friendly efficient method was successfully applied in the separation and determination of three chemical dyes in soybean products.

Sensitive Electrochemical Sensor Based On an Aminated MIL-101(Cr) MOF for the Detection of Tartrazine

The aminated metal-organic framework H₂N-MIL-101(Cr) was used as the carbon paste electrode (CPE) modifier for the determination of tartrazine (Tz) in soft drinks. The amino material was characterized by electrochemical impedance spectroscopy and showed significantly faster electron transfer with lower charge-transfer resistance (0.13 kΩ) compared to the electrode modified with the unfunctionalized MIL-101(Cr) material (1.1 kΩ). The H₂N-MIL-101(Cr)-modified CPE [H₂N-MIL-101(Cr)-CPE] was then characterized by cyclic voltammetry (CV) using [Fe(CN)₆]^3- and [Ru(NH₃)₆]³⁺ ions as the redox probes, showing good accumulation of [Fe(CN)₆]^3- ions on the electrode surface. A CV scan of Tz in Britton Robinson buffer solution revealed an irreversible system with an oxidation peak at +0.998 V versus Ag/AgCl/KCl. Using CV and differential pulse voltammetry, an electrochemical method for quantifying Tz in aqueous medium was then developed. Several parameters that affect the accumulation and detection steps were optimized. Optimal detection of Tz was achieved after 180 s of accumulation in Britton Robinson buffer solution (pH 2) using 2 mg of H₂N-MIL-101(Cr) material. Under optimal conditions, the sensor exhibited a linear response in the concentration range of 0.004-0.1 μM and good detection sensitivity (35.4 μA μM^-1), and the detection limit for Tz was found to be 1.77 nM (S/N = 3). Satisfactory repeatability, stability, and anti-interference performance were also achieved on H₂N-MIL-101(Cr)-CPE. The sensor was applied to commercial juices, and the results obtained were approximately similar to those given by UV-vis spectrophotometry.

An electrochemical sensor based on hierarchical nickel oxide nanostructures doped with indium ions for voltammetric simultaneous determination of sunset yellow and tartrazine colorants in soft drink powders

The current study was designed to develop a single-step and simple approach to effectively fabricate three-dimensional raspberry-like In³⁺/NiO hierarchical nanostructures (In³⁺/NiO RLHNSs) as a modifier, which was subsequently characterized by the techniques of X-ray diffraction (XRD), energy dispersive spectrometry (EDS) and field emission scanning electron microscopy (FE-SEM). The new prepared nano-modifier was practically used to co-detect electrochemically sunset yellow and tartrazine dyes. Potent sensitivity and acceptable selectivity were obtained for the produced In³⁺/NiO RLHNSs to co-detect both the food colorants, thus providing oxidation peaks in differential pulse voltammetry (DPV) with a peak potential separation of ca. 190 mV. The results showed a 5.14-fold and 8.07-fold increase in the electrochemical response of our modified electrode to sunset yellow and tartrazine, respectively, compared to the control (the unmodified electrode). Limits of detection of 2.7 and 3.1 nM were calculated for sunset yellow and tartrazine, respectively. The results from the interaction of common food additives showed satisfactory outcomes for the application of this method in determining sunset yellow and tartrazine in several beverage specimens. Other useful documentation was obtained for the production of portable food additive sensors.

Development of a highly sensitive fluorescence method for tartrazine determination in food matrices based on carbon dots

In this work, an ultrasensitive sensing system based on fluorescent carbon dots (CDs) was developed for the tartrazine (Tar) determination. The CDs were prepared via a simple one-pot hydrothermal method with m-phenylenediamine as the only precursor. The physical and chemical properties were in detail characterized by transmission electron microscopy (TEM), MALDI-TOF MS, UV-vis absorption and photoluminescence (PL) spectroscopy, elemental analysis, and Fourier transform infrared spectroscopy (FTIR). Upon exposure to Tar, the fluorescence of CDs was efficiently quenched via the dynamic interaction between CDs and Tar as well as the inner filter effect (IFE). With this information, the CDs were proposed as a fluorescence probe for Tar detection. It was found that CDs had high sensitivity and selectivity for Tar sensing, and the linear relationship was observed in the range of 0.01-25.0 μM with the corresponding detection limit (3σ/k) of 12.4 nM, which is much more sensitive than any of the existed CD-based sensing platform. The investigated sensing system was finally utilized for Tar sensing in various food matrices with a high degree of accuracy. The spiked recoveries were in a range of 96.4-105.2%, and the relative standard deviations (RSDs) were lower than 4.13%. This work highlights the great application prospects of CDs for Tar sensing in a rapid, simple, and sensitive way.

Electropolymerized melamine for simultaneous determination of nitrite and tartrazine

Poly(melamine) (PMel) was synthesized via the electropolymerization of melamine monomer, which was then characterized by field-emission scanning electron microscopy (FESEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The possible polymerization mechanisms of melamine were also revealed by FT-IR spectroscopy and UV-Vis spectroscopy. Next, the PMel modified GCE (PMel/GCE) was used for the simultaneous determination of nitrite (NO₂^-) and tartrazine, and the parameters were optimized. The kinetic study showed that the electrochemical oxidation of nitrite and tartrazine at the surface of PMel/GCE is a typical surface-controlled electrode process. Under the optimun conditions, the developed sensor outperformed those previously reported, and it also exhibited high selectivity and reproducibility. Finally, the PMel/GCE was used for the simultaneous determination of nitrite and tartrazine in foodstuffs, and the results indicated that the proposed sensor could be a promising candidate for accurate determination of nitrite and tartrazine in real food samples.

Application of quadrupole-Orbitrap high-resolution mass spectrometry in rapid screening and identification of synthetic dyes in herbal medicines

In this work, a method combining ultra-high performance liquid chromatography and hybrid quadrupole-Orbitrap high-resolution mass spectrometry (HR-MS) was developed and validated for use in the simultaneous screening, identification, and quantification of 21 synthetic dyes in herbal medicines. To optimize the chromatographic conditions, we used a combined Full mass scan and data-dependent MS/MS (Full MS/dd-MS²) approach in positive and negative ion mode. Under this mode, selected ions with given fragmentation energy were subjected to a dd-MS² scan following a Full MS scan. The selectivity of this method was effectively improved using 70,000 full width at half maximum mass resolution and narrow mass window (typically 5 ppm), and a single injection was sufficient for simultaneous identification and quantification of 21 synthetic dyes within 10 min. The combined method was fully validated and complies with all criteria for selectivity, sensitivity, calibration curve linearity, accuracy, precision, recovery, matrix effect, and stability. All analytes showed excellent linear relationships as all the coefficients of determination (r²) are greater than 0.9978 over wide ranges of concentrations (e.g. 1.0-500 ng/mL for sunset yellow). The validated method was employed to detect synthetic dyes in herbal medicines and was demonstrated to provide a reliable technical basis for drug regulation and public health protection.

Ultra-High-Throughput Analytical Strategy Based on UHPLC-DAD in Combination with Syringe Filtration for the Quantitation of Nine Synthetic Colorants in Beverages: Impacts of Syringe Membrane Types and Sample pH on Recovery

An ultra-high-throughput approach based on ultra-high-performance liquid chromatography with diode array detection (UHPLC-DAD) in combination with simple syringe filtration was successfully developed and validated for the quantitation of nine synthetic colorants in beverages. The recoveries of the colorants from the beverages were found to be dramatically affected by the syringe filter membrane types and pH of the sample solution. The high recoveries of the nine colorants (92.7-105.9%) were achieved by syringe filtration with poly(vinylidene difluoride) membrane following the pH adjustment of sample solution at pH 7.0. The sample treatment procedure was very simple and took only 1 min. The fast chromatographic separation (1 min) of the nine synthetic colorants was achieved by UHPLC-DAD using a C18-core-shell column. This analytical approach (UHPLC-DAD combined with syringe filtration) took only approximately 3 min. The established method was ultrafast, sensitive, precise, accurate, and reliable. The method was successfully applied to rapidly determine the 9 colorants in 17 beverages.

Voltammetric sensor for tartrazine determination in soft drinks using poly ( p -aminobenzenesulfonic acid)/zinc oxide nanoparticles in carbon paste electrode

Zinc oxide nanoparticles (ZnO NPs) and p-aminobenzenesulfonic acid (p-ABSA) were used to fabricate a modified electrode, as a highly sensitive and selective voltammetric sensor, for the determination of tartrazine. A fast and easy method for the fabrication of poly p-ABSA (Pp-ABSA)/ZnO NPs-carbon paste electrode (Pp-ABSA/ZnO NPs-CPE) by cyclic voltammetry was used. By combining the benefits of Pp-ABSA, ZnO NPs, and CPE, the resulted modified electrode exhibited outstanding electrocatalytic activity in terms of tartrazine oxidation by giving much higher peak currents than those obtained for the unmodified CPE and also other constructed electrodes. The effects of various experimental parameters on the voltammetric response of tartrazine were investigated. At the optimum conditions, the sensor has a linear response in the concentration range of 0349–5.44 μM, a good detection sensitivity (2.2034 μA/μM), and a detection limit of 80 nM of tartrazine. The proposed electrode was used for the determination of tartrazine in soft drinks with satisfactory results.

Food colors: Existing and emerging food safety concerns

Food colors are added to different types of commodities to increase their visual attractiveness or to compensate for natural color variations. The use of these additives is strictly regulated in the European Union, the United States, and many other countries worldwide. There is a growing concern about the safety of some commonly used legal food colorants and there is a trend to replace the synthetic forms with natural products. Additionally, a number of dyes with known or suspected genotoxic or carcinogenic properties have been shown to be added illegally to foods. Robust monitoring programs based on reliable detection methods are required to assure the food is free from harmful colors. The aim of this review is to present an up to date status of the various concerns arising from use of color additives in food. The most important food safety concerns in the field of food colors are lack of uniform regulation concerning legal food colors worldwide, possible link of artificial colors to hyperactive behavior, replacement of synthetic colors with natural ones, and the presence of harmful illegal dyes-both known but also new, emerging ones in food. The legal status of food color additives in the EU, United States, and worldwide is summarized. The reported negative health effects of both legal and illegal colors are presented. The European Rapid Alert System for Food and Feed notifications and US import alerts concerning food colors are analyzed and trends in fraudulent use of color additives identified. The detection methods for synthetic colors are also reviewed.

A Review of Extraction and Analytical Methods for the Determination of Tartrazine (E 102) in Foodstuffs

Tartrazine is an azo food dye, which is orange-colored and water soluble. It is usually used in foods, pharmaceuticals, cosmetics, and textiles. Tartrazine has the potential to cause an adverse health effect on humans, such as hyperactivity in children, allergy, and asthma. Joint FAO/WHO Expert Committee on Food Additive and EU Scientific Committee for Food have standardized the acceptable daily intake for tartrazine that is 7.5 mg kg^-1 body weight. Many researchers have detected the presence of tartrazine for monitoring the quality and safety of food products. In this review paper, we highlighted various tartrazine detection and extraction methods. Some of the analytical methods are available such as high-performance liquid chromatography, electrochemical sensor, thin-layer chromatography, spectrophotometry, capillary electrophoresis, and liquid chromatography-tandem mass spectrometry. Also, we discuss following extraction steps: liquid-liquid extraction, solid-phase extraction, membrane filtration, cloud point extraction, and other extraction method. In addition, a brief overview is presented explaining the synthesis process and metabolism of tartrazine and the maximum permitted level in different countries. This review paper will give an insight into different extraction and analytical methods for the determination of tartrazine in healthy foods, which will attract the attention of public toward food safety and quality, and also the interest of food industry and government bodies.

Determination of dyes in cosmetic products by micro-matrix solid phase dispersion and liquid chromatography coupled to tandem mass spectrometry

A simple method based on micro-matrix solid phase dispersion (MSPD) followed by liquid chromatography-mass spectrometry (LC-MS/MS) has been developed for the rapid and simultaneous determination of nine regulated water-soluble dyes in personal care and decorative products. The proposed miniaturized extraction procedure was optimized by means of experimental designs in order to obtain the highest extraction efficiency. Under the optimal selected conditions, the method was validated showing satisfactory performance in terms of linearity, sensitivity, and intra-day and inter-day precision. Recoveries were evaluated in different cosmetic matrices and they can be considered quantitative with average values between 70 and 120% with relative standard deviations (RSD) lower than 15%. Finally, the validated method was applied to 24 samples of cosmetic and personal care products, including decorative makeup, lipsticks, lip gloss, toothpastes, regenerating creams, shampoos, and eye shadows, among others, to cover a broad range of commercial real samples. Seven of the analyzed dyes were detected, being declared all of them in the label list of ingredients. More than 50% of the samples contained at least two dyes. Tartrazine was the most frequently found (50% of the samples) at concentration levels of 0.243-79.9μgg(-1). Other targets were found in 1-9 samples, highlighting the presence of Quinoline at high concentration (>500μgg(-1)) in a toothpaste sample.

Green Synthesis of Fluorescent Carbon Dots for Selective Detection of Tartrazine in Food Samples

A simple, economical, and green method for the preparation of water-soluble, high-fluorescent carbon quantum dots (C-dots) has been developed via hydrothermal process using aloe as a carbon source. The synthesized C-dots were characterized by atomic force microscope (AFM), transmission electron microscopy (TEM), fluorescence spectrophotometer, UV-vis absorption spectra as well as Fourier transform infrared spectroscopy (FTIR). The results reveal that the as-prepared C-dots were spherical shape with an average diameter of 5 nm and emit bright yellow photoluminescence (PL) with a quantum yield of approximately 10.37%. The surface of the C-dots was rich in hydroxyl groups and presented various merits including high fluorescent quantum yield, excellent photostability, low toxicity and satisfactory solubility. Additionally, we found that one of the widely used synthetic food colorants, tartrazine, could result in a strong fluorescence quenching of the C-dots through a static quenching process. The decrease of fluorescence intensity made it possible to determine tartrazine in the linear range extending from 0.25 to 32.50 μM, This observation was further successfully applied for the determination of tartrazine in food samples collected from local markets, suggesting its great potential toward food routine analysis. Results from our study may shed light on the production of fluorescent and biocompatible nanocarbons due to our simple and environmental benign strategy to synthesize C-dots in which aloe was used as a carbon source.

Removal of basic dye Auramine-O by ZnS:Cu nanoparticles loaded on activated carbon: optimization of parameters using response surface methodology with central composite design

FESEM images of the prepared ZnS:Cu-NPs-AC.

TNPs as a novel fluorescent sensor for the selective recognition of fast green FCF: a spectrofluorimetric approach

The fast green FCF dye adsorbed over the surface of the CTAB stabilized tetracene nanoparticles (TNPs) forms a stable, non-fluorescent ground state complex and quenches fluorescence of nanoparticle sensor.

The application of a Tchebichef moment method to the quantitative analysis of multiple compounds based on three-dimensional HPLC fingerprint spectra

A Tchebichef moment method was proposed and used to successfully quantify four compounds based on 3D HPLC-PAD spectra.

Simultaneous determination of eight flavonoids in propolis using chemometrics-assisted high performance liquid chromatography-diode array detection

A fast analytical strategy of second-order calibration method based on the alternating trilinear decomposition algorithm (ATLD)-assisted high performance liquid chromatography coupled with a diode array detector (HPLC-DAD) was established for the simultaneous determination of eight flavonoids (rutin, quercetin, luteolin, kaempferol, isorhamnetin, apigenin, galangin and chrysin) in propolis capsules samples. The chromatographic separation was implemented on a Wondasil™ C18 column (250mm×4.6mm, 5μm) within 13min with a binary mobile phase composed of water with 1% formic acid and methanol at a flow rate of 1.0mLmin(-1) after flavonoids were only extracted with methanol by ultrasound extraction for 15min. The baseline problem was overcome by considering background drift as additional compositions or factors as well as the target analytes, and ATLD was employed to handle the overlapping peaks from analytes of interest or from analytes and co-eluting matrix compounds. The linearity was good with the correlation coefficients no less than 0.9947; the limit of detections (LODs) within the range of 3.39-33.05ngmL(-1) were low enough; the accuracy was confirmed by the recoveries ranged from 91.9% to 110.2% and the root-mean-square-error of predictions (RMSEPs) less than 1.1μg/mL. The results indicated that the chromatographic method with the aid of ATLD is efficient, sensitive and cost-effective and can realize the resolution and accurate quantification of flavonoids even in the presence of interferences, thus providing an alternative method for accurate quantification of analytes especially when the complete separation is not easily accomplished. The method was successfully applied to propolis capsules samples and the satisfactory results were obtained.

Deconvolution of overlapping spectral polymer signals in size exclusion separation-diode array detection separations by implementing a multivariate curve resolution method optimized by alternating least square

Peaks eluting from a size exclusion separation (SEC) are often not completely baseline-separated due to the inherent dispersity of the polymer. Lowering the flow rate is sometimes a solution to obtain a better physical separation, but results in a longer retention time, which is often not desirable. The chemometrical deconvolution method discussed in this work provides the possibility of calculating the contribution of each peak separately in the total chromatogram of overlapping peaks. An in-house-developed MATLAB script differentiates between compounds based on their difference in UV-spectrum and retention time, using the entire 3D retention time UV-spectrum. Consequently, the output of the script offers the calculated chromatograms of the separate compounds as well as their respective UV-spectrum, of which the latter can be used for peak identification. This approach is of interest to quantitate contributions of different polymer types with overlapping UV-spectra and retention times, as is often the case in, for example, copolymer or polymer blend analysis. The applicability has been proven on mixtures of different polymer types: polystyrene, poly(methyl methacrylate) and poly(ethoxyethyl acrylate). This paper demonstrates that both qualitative and quantitative analyses are possible after deconvolution and that alternating concentrations of adjacent peaks do not significantly influence the obtained accuracy.