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In this work, a new supramolecular solvent (SUPRAS) was prepared for the first time using hexafluorobutanol (HFB) and farnesol (FO). FO acts as an amphiphile and HFB as a coacervation inducer and density regulator. The method of dispersive liquid‐liquid microextraction followed by high‐performance liquid chromatography, supported by a vortex technique, was established using the prepared SUPRAS for the determination of Sudan dyes in aqueous samples. The extraction parameters, including FO content, HFB content, vortex time, salt addition, and solution pH, were thoroughly investigated and optimized. Under the optimized conditions, the linearity range is 10–750 ng/mL for Sudan I, and 10–1000 ng/mL for Sudan III and Sudan IV, respectively. The limits of detection for Sudan dyes were in the range of 0.8–3.1 ng/mL. The inter‐ and intra‐day relative standard deviations for Sudan dyes were in the range of 1.3%–4.1% and 0.2%–2.6%, respectively. Finally, the proposed method was applied to the determination of Sudan dyes in beverage and river water samples with recoveries ranging from 93.9% to 122.1%. Compared to conventional techniques for the extraction of Sudan dyes in real samples, the proposed method is simpler, faster, and more environmentally friendly. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Shenyang Pharmaceutical University is the property of Shenyang Pharmaceutical University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study uses phosphoric acid activation and carbonization processes to create Nelumbinis stamen activated carbon (NSAC) from food waste precursors in a single step. The resultant NSAC was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, N2 adsorption/desorption methods, X-ray diffraction, and Raman spectroscopy for surface morphology, structural features, and surface chemistry. The operating conditions, including the carbonization temperature, amount of adsorbent, adsorption temperature, and aqueous solution pH, were optimized to maximize the removal efficiency of Sudan dyes. Therefore, the values of the optimized conditions were selected as 500℃ for the carbonization temperature, 0.4 g L−1 for the adsorbent dose, 50℃ for the adsorption temperature, and a pH of 3.0 for the aqueous solution. In addition, the pseudosecond-order kinetic model and Langmuir isotherm model fit the experimental data best. Moreover, the maximum adsorption capacities of the four dyes on NSAC calculated according to the Langmuir adsorption model were in the range of 34.60–38.97 mg g−1. Furthermore, thermodynamic results revealed that the adsorption process was spontaneous, feasible, and endothermic. Finally, the activated carbon was used for the adsorption of Sudan dye solution from chrysanthemum tea and cooked egg samples, and the results showed that the adsorbent could be successfully used for the adsorption and removal of the dyestuff solution. [ABSTRACT FROM AUTHOR]

This study introduced a new microextraction method named temperature‐induced dispersive solid‐phase extraction. The performance of the method was demonstrated with the determination of Sudan dyes in food and natural water samples. In this method, a low quantity of sorbent was added to the aqueous solution and the mixture was shaken manually for about one minute. Then, the solution was heated in an ultrasonic water bath, and the sorbent was dissolved. Subsequently, the solution was cooled down with ice water, and consequently, the solubility of the sorbent was reduced in the sample solution and became cloudy. The phase separation was accelerated by centrifugation. The upper liquid phase was picked up using a syringe, and the remainder was solved in methanol and introduced into the HPLC for analysis. Various parameters affecting the extraction yield were evaluated. Analytical parameters, including limits of detection (0.011–0.016 μg/L) and quantification (0.038–0.055 μg/L), relative standard deviations (2.3%–3.1%), and preconcentration factor (40) proved the high efficiency of the developed method for the analysis of Sudan dyes. The proposed method was used to measure Sudan dyes in water and food samples and showed good extraction recoveries (95.0%–103.5%). [ABSTRACT FROM AUTHOR]

In this study, a simple, economical and rapid colorimetric assay was developed for the detection of Sudan, in which Sudan-binding aptamer was used as recognition element, unmodified gold nanoparticles (AuNPs) as sensing signal, and poly(diallyldimethylammonium chloride) (PDDA) as inducer for gold nanoparticle aggregation. The sensitivity, accuracy and specificity of developed method were evaluated under optimized condition. Finally, the colorimetric sensor was applied to detection Sudan in food samples, and the results were compared with GB standard method (GB/T 19681-2005). The best procedure for Sudan analysis in our system was: The concentration of aptamer at 5 nmol/L, the concentration of PDDA at 20 nmol/L, and the reaction time was 4 min. The correlation between concentration of Sudan III and absorbance ratio of gold nanoparticles (A650nm/A530nm) was observed to be linear within the range of 3.13 to 50 ng/mL. The limit of visual detection was 3.13 ng/mL by naked-eye observation. The detection time was 5 min. The colorimetric sensor had high specificity for Sudan I, II, III and IV, and no cross-reactivity towards sunset yellow, tartrazine, and 1-amino-2-methylanthraquinone. Further, the colorimetric sensor was applied to measure Sudan Ⅲ in spiked real samples, and the recoveries were in the range of 85.4%~102.5%, with relative standard deviations of 3.37%~6.75%. Our study provides a simple, fast, and easy to read method for Sudan analysis, which can be applied in future on-site detection in food samples.

The environmental pollution, particularly water pollution, has gradually caused severe human health issues. Organic dyes are one of the most emerging pollutants in the environment. In the present study, graphene oxide (GO) was functionalized with chitosan (CS) and magnetic nanoparticles (Fe-NPs) and tested to remove Sudan I, II, III, and IV dyes from water. The synthesized GO-CS-Fe was characterized using UV–vis, SEM, TEM, EDX, and FTIR spectroscopy, and confirmed the structural composition of nanocomposite, with the Fe-NPs dimension over the GO-CS surface to be 31–44 nm. The effects of various experimental factors; time,pH, adsorbent amount, dyes concentrations, and temperature were executed using the batch experiment. The experimental data were fitted to pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich kinetic models. The isotherm models parameters of the Langmuir, Freundlich, Redlich–Peterson, Temkin, and Hill isotherms, along with the thermodynamics parameters were also calculated. The data was explained by the Langmuir isotherm model with maximum adsorption capacities for Sudan I, II, III, and IV as 360.6, 353.7, 351.0, and 347.6 mg/g, respectively. The rapid uptake of the dyes fitted the pseudo-second-order kinetic, asserting that the adsorption was diffusion controlled. The process was spontaneous and endothermic in nature. The reusability study of GO-CS-Fe was performed up to five cycles. The nanocomposite can retain its efficacy even after the considered cycles. In conclusion, the GO-CS-Fe nanocomposite has exhibited a high potential for removing Sudan dyes from the aqueous solution due to its high adsorption and regeneration capability. [ABSTRACT FROM AUTHOR]

Sudan dyes were investigated in branded and non-branded spices, commonly available in the markets of Karachi, Pakistan. High performance liquid chromatography (HPLC) with a variable wavelength detector (VWD) was applied to determine Sudan dyes I-IV. The non-branded samples had higher concentrations of Sudan dyes than the maximum limits of 0.1 mg/kg. The highest concentration of Sudan dye (I) was found in turmeric powder (8460 mg/kg) and the lowest concentration (1.50 mg/kg) of Sudan (IV) in Chaat Masala. This indicates that the use of non-branded spices is not safe, whereas no Sudan dye was found in the branded spice samples. Further studies regarding the higher carcinogenic risk posed by Sudan dye adulterated spices in Pakistan is strongly advised. [ABSTRACT FROM AUTHOR]

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Azo compounds such as the Sudan dyes I–IV are frequently used illegally as colorants and added to a wide range of foods. These compounds have been linked to a number of food safety hazards. Several methods have been proposed to detect food contamination by azo compounds and most of these are laboratory based; however, the development of reliable and portable methods for the detection and quantification of food contaminated by these chemicals in low concentration is still needed due to their potentially carcinogenic properties. In this study, we investigated the ability of surface enhanced Raman scattering (SERS) combined with chemometrics to quantify Sudan I–IV dyes. SERS spectra were acquired using a portable Raman device and gold nanoparticles were employed as the SERS substrate. As these dyes are hydrophobic, they were first dissolved in water: acetonitrile (1:10, v/v) as single Sudan dyes (I–IV) at varying concentrations. SERS was performed at 785 nm and the spectra were analyzed by using partial least squares regression (PLS-R) with double cross-validations. The coefficient of determination (Q2) were 0.9286, 0.9206, 0.8676 and 0.9705 for Sudan I to IV, respectively; the corresponding limits of detection (LOD) for these dyes were estimated to be 6.27 × 10−6, 5.35 × 10−5, 9.40 × 10−6 and 1.84 × 10−6 M. Next, quadruplex mixtures were made containing all four Sudan dyes. As the number of possible combinations needed to cover the full concentration range at 5% intervals would have meant collecting SERS spectra from 194,481 samples (214 combinations) we used a sustainable solution based on Latin hypercubic sampling and reduced the number of mixtures to be analyzed to just 90. After collecting SERS spectra from these mixture PLS-R models with bootstrapping validations were employed. The results were slightly worse in which the Q2 for Sudan I to IV were 0.8593, 0.7255, 0.5207 and 0.5940 when PLS1 models (i.e., one model for one dye) was employed and they changed to 0.8329, 0.7288, 0.5032 and 0.5459 when PLS2 models were employed (i.e., four dyes were modelled simultaneously). These results showed the potential of SERS to be used as a high-throughput, low-cost, and reliable methods for detecting and quantifying multiple Sudan dyes in low concentration from illegally adulterated samples. [ABSTRACT FROM AUTHOR]

Paprika is a spice whose composition and characteristics vary with its geographical origin and additionally is illegally adulterated with dyes to improve its appearance. This work proposes a strategy based on Fourier-transform near infrared (FT-NIR) analysis and chemometric tools for its authentication and detection of fraud. A total of 115 paprika samples were analyzed, including paprika with protected designation of origin (PDO) labels from Spain, France and Hungary, and samples from China and Zambia. The proposed orthogonal partial least squares-discriminant analysis (OPLS-DA) models allow to distinguish paprika according to its PDO and variety, as well as to identify adulteration with Sudan dyes or Congo red. Partial least squares regressions allow to quantify the adulterant in paprika from 0.1 to 5 %. Chemometric models achieved high classification success rates and suitable linearities. The proposed strategy is presented as a comprehensive and effective tool to ensure paprika quality and authenticity, including the detection and quantification of adulteration with commercial dyes. • Paprika geographical origin and variety are established. • FT-NIR analysis and chemometric tools allow authentication and detection of fraud. • Protected Designation of Origin paprika from Spain, France and Hungary are analyzed. • Partial least squares regressions allow to quantify dye adulteration up to 5 %. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A novel, rapid, and reliable ultra-high performance supercritical fluid chromatography (UHPSFC) method was developed to correctly separate and quantitatively determine Sudan dyes in chilli products. The effect of different separation parameters on the retention characteristics of Sudan dyes was investigated. The results showed that diode array detection of Sudan I–II was accomplished at 480 nm, and that of Sudan III–IV at 500 nm. In the analysis of Sudan dyes, the whole analysis time was less than 10 minutes, the method had a limit of detection and limit of quantification of 0.25 μg/mL and 0.50 μg/mL, respectively. All calibration curves had good linearity (r2 > 0.9989) within the tested concentration ranges. The method had intra- and inter-day precision of less than 3.5% and 4.1%, respectively, with a recovery between 96.58% and 104.50%, and a relative standard deviation of less than 4.4%. The method was successfully applied to analyze chilli product sample.

A sensitive and a precise method was developed for the quantification of different Sudan dyes in some Egyptian food samples. They were analyzed utilizing two-fragment ion transition under multiple reaction monitoring (MRM) mode. Separation was carried out on Kinetex 2.6u C18 100 A (75 mm × 4.6 mm) phenomenex using isocratic elution with 10:90% water and acetonitrile containing 2.0 mmol/L ammonium formate and 0.2% formic acid. The validation parameters were obtained and verified. The linearity was 0.2–10.0 ng/mL with r2 > 0.9975. LOD and LOQ were 0.06 and 0.19 ng/mL, respectively, for Sudan (I, II) whereas they were 0.07 and 0.23 ng/mL, respectively, for Sudan (III and IV), and Sudan orange G. Recoveries are ranged from 78.79 to 110.49%. The method has been successfully applied for the quantification of these dyes in 60 food samples such as spices, chili powder, turmeric, paprika, and curry. The results show that about 55% of the randomly selected food samples were adulterated with the banned dyes. [ABSTRACT FROM AUTHOR]

Azo compounds such as the Sudan dyes I–IV are frequently used illegally as colorants and added to a wide range of foods. These compounds have been linked to a number of food safety hazards. Several methods have been proposed to detect food contamination by azo compounds and most of these are laboratory based; however, the development of reliable and portable methods for the detection and quantification of food contaminated by these chemicals in low concentration is still needed due to their potentially carcinogenic properties. In this study, we investigated the ability of surface enhanced Raman scattering (SERS) combined with chemometrics to quantify Sudan I–IV dyes. SERS spectra were acquired using a portable Raman device and gold nanoparticles were employed as the SERS substrate. As these dyes are hydrophobic, they were first dissolved in water: acetonitrile (1:10, v/v) as single Sudan dyes (I–IV) at varying concentrations. SERS was performed at 785 nm and the spectra were analyzed by using partial least squares regression (PLS-R) with double cross-validations. The coefficient of determination (Q2) were 0.9286, 0.9206, 0.8676 and 0.9705 for Sudan I to IV, respectively; the corresponding limits of detection (LOD) for these dyes were estimated to be 6.27 × 10−6, 5.35 × 10−5, 9.40 × 10−6 and 1.84 × 10−6 M. Next, quadruplex mixtures were made containing all four Sudan dyes. As the number of possible combinations needed to cover the full concentration range at 5% intervals would have meant collecting SERS spectra from 194,481 samples (214 combinations) we used a sustainable solution based on Latin hypercubic sampling and reduced the number of mixtures to be analyzed to just 90. After collecting SERS spectra from these mixture PLS-R models with bootstrapping validations were employed. The results were slightly worse in which the Q2 for Sudan I to IV were 0.8593, 0.7255, 0.5207 and 0.5940 when PLS1 models (i.e., one model for one dye) was employed and they changed to 0.8329, 0.7288, 0.5032 and 0.5459 when PLS2 models were employed (i.e., four dyes were modelled simultaneously). These results showed the potential of SERS to be used as a high-throughput, low-cost, and reliable methods for detecting and quantifying multiple Sudan dyes in low concentration from illegally adulterated samples.

Ghanaian consumers’ confidence and trust in palm oil have become weak over the past few years. This research seeks to evaluate the quality and safety (Sudan adulteration) parameters of palm oil samples from seven major cities in Ghana using a completely randomized design with three replications. In all, 70 samples of palm oil were collected from different locations (Accra, Kumasi, Takoradi, Ho, Cape Coast, Koforidua and Sunyani. Parameters measured included: free fatty acid (FFA), acid value (AV), peroxide value (PV), saponification value (SV), moisture content (MC), iodine value (IV) and authenticity (Sudan dye adulteration). The results revealed that the quality and safety of palm oil samples in these cities are fairly different as some show above limits. All seven regions recorded IV values lower than the 55.0–55.0 mg/L range. Four out of the 7 regions recorded values above the stipulated standards (0.25%) for MC three for SP (211.6 mg/g) and two for PV (11.3 mEq/Kg). However, data from oil acidity determination were the source of worry as all regions had values above the 10.0 mg KOH/g acidity maximal limit for CPO, and the Central region registered more than two times (22.5 mg KOH/g) the limit. Sudan 4 dye, which should not be found in CPO was also detected in samples from all seven regions. Again, the Central region recorded a value as high as 6.18 mg/L. With regards to the fact that high acidity could be an indication of CPO hydrolysis, coupled with available moisture which facilitates degradation reactions involved in food spoilage, one can perhaps infer that the overall quality of CPO samples assessed was poor. Additionally, the CPO samples were not safe for consumption. There was evidence of adulteration with Sudan dyes, particularly Sudan 4.

In this study, a simple Benzimidazole based bifunctional chemosensor 4-(2-(3,4-dimethoxyphenyl)-1H-benzo[d]imidazol-6-yl) benzene-1,2-diamine, L was synthesized and characterized. The sensor proved to be selective and sensitive towards detecting banned azo dyes Sudan Dye I, II, and Metanil Yellow via fluorescence turn-off response. The proposed mechanism of fluorescence quenching was the inner filter effect. LODs for Sudan I, II, and Metanil Yellow were found to be 0.009 µM, 0.012 µM, and 0.0073 µM, respectively. The developed chemosensor also showed a colorimetric response towards Cu (II) ions via an apparent color change from yellow to pink. LOD for Cu (II) ions was found to be 1.2 µM. The synthesized benzimidazole based bifunctional chemosensor was adequately tested to determine Sudan I in Red chili powder and red Food color samples, Metanil yellow in turmeric powder, and Cu(II) packaged coconut water. [ABSTRACT FROM AUTHOR]

[Display omitted] • CDs@ZIF-8 was designed and synthesized for the detection of Sudan dyes. • The CDs@ZIF-8 demonstrated superior pH resistance when compared to CDs. • CDs@ZIF-8 offers higher sensitivity and wider detection range for Sudan I than CDs. • The method has been used in the detection of Sudan I in foodstuffs. In this manuscript, we synthesized CDs@ZIF-8 through a one-step, in-situ method by integrating green-emitting carbon dots (CDs) with zeolitic imidazolate framework-8 (ZIF-8). The resulting CDs@ZIF-8 was utilized as an ultrasensitive probe for detection, leveraging the inner filter effect. The analysis demonstrated the capability to detect Sudan dyes. Sudan I, for example, could be detected within a concentration range spanning from 0.25 to 70 μM, achieving a remarkable detection limit of 76.56 nM. This established method was effectively employed for detecting Sudan I in paprika. Compared with CDs, CDs@ZIF-8 exhibited a 3.32-fold increase in sensitivity and a wider detection range. This enhanced performance was attributed to the porous ZIF-8, which allowed for the enrichment of targets around CDs and avoided the aggregation of CDs. Additionally, embedding the CDs in ZIF-8 improved their pH stability. Our study provides a new approach for using CDs under limited conditions by leveraging metal–organic frameworks. [ABSTRACT FROM AUTHOR]

In this work, a rapid method termed as microfunnel-filter-based emulsification microextraction is coupled with high performance liquid chromatography for a simple determination of the banned Sudan dyes (I, II, and III) in fruit juice, spice, and water samples. According to the method, in order to speed-up the extraction and concentration of the target analytes, a micro-volume of a low-density organic solvent (1-octanol) is dispersed into an aqueous sample solution (45 mL), and a simple separation of the extractant phase is obtained using a syringe filter and microfunnel. The method provides a low-toxic extraction, it is centrifuge-less, and the extraction process is totally performed in a few minutes. The influencing factors including the type of organic solvent, number of extraction cycles, pH of the sample solution, and volume of the extraction solvent are investigated to achieve the optimal conditions. A good linearity (in the range of 0.7–1000 ng mL−1 (R2 > 0.995)) and a low limit of detection (in the range of 0.2-0.5 ng mL−1) are obtained, the extraction recovery is in the range of 94-107%, and the developed method provides a high enrichment factor (in the range of 294-354).

In this work, a new generation of hydrophobic deep eutectic solvents (DESs) was prepared using eugenol (as hydrogen bond donor) and benzyltriethylammonium bromide, benzyltributylammonium bromide, benzyltriethylammonium chloride and benzyltributylammonium chloride (as hydrogen bond acceptor) in different molar ratios. These DESs were applied to vortex-assisted dispersive liquid-liquid microextraction of Sudan dyes from food samples, followed by high-performance liquid chromatographic determination. The influencing parameters, including the type of DES, amount of DES, extraction time, solution pH and salt addition, were investigated and optimized. Under the optimized conditions, a linear range of 2–1000 ng mL−1 with determination coefficients of <0.999 was obtained. Limits of detection and limits of quantification were in the range of 0.5 to 1 ng mL−1 and 2 to 3 ng mL−1, respectively. The proposed method was successfully used in the determination of Sudan dyes in chili sauce, chili powder and ketchup, and satisfactory recoveries of between 89.9 and 119.3% were obtained, with relative standard deviations in the range of 0.1–6.8%. The proposed method is simple, green and efficient, and can be applied to determine Sudan dyes in complex matrices. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The detection of low‐concentration oily pollutants, especially when in oil/water mixtures or real food matrix, still faces great challenges. Integrating adsorption and plasmonic hot‐spot on single material will be an efficient method for ultra‐sensitively detecting oily dyes or contaminants in oil/water mixtures via surface‐enhanced Raman scattering. Herein, the superhydrophobic/superoleophilic polyacrylonitrile (PAN)/Ag aerogels which can quickly absorb and detect low‐concentration oily dyes in oil/water mixtures are successfully fabricated. In order to solve the contradiction that abundant hydrophilic‐Ag nanoparticles are adverse to the superhydrophobicity of substrate but in favor of Raman signals, the superhydrophobic/superoleophilic PAN/Ag aerogels are prepared through two steps: substrate‐seeding and secondary‐growth. The lowest detection concentration of 10−12m for oil‐soluble Sudan III in oil/water mixtures is achieved by using PAN/overgrown Ag (PAN/O‐Ag) nanofibrous aerogels as absorbent, which is superior to most of reported materials. Moreover, a detection limit of 0.1 ppm of Sudan III spiked in chilli powder is obtained using PAN/O‐Ag aerogels. [ABSTRACT FROM AUTHOR]

A novel, rapid, and reliable ultra-high performance supercritical fluid chromatography (UHPSFC) method was developed to correctly separate and quantitatively determine Sudan dyes in chilli products. The effect of different separation parameters on the retention characteristics of Sudan dyes was investigated. The results showed that diode array detection of Sudan I–II was accomplished at 480 nm, and that of Sudan III–IV at 500 nm. In the analysis of Sudan dyes, the whole analysis time was less than 10 minutes, the method had a limit of detection and limit of quantification of 0.25 μg/mL and 0.50 μg/mL, respectively. All calibration curves had good linearity (r2 > 0.9989) within the tested concentration ranges. The method had intra- and inter-day precision of less than 3.5% and 4.1%, respectively, with a recovery between 96.58% and 104.50%, and a relative standard deviation of less than 4.4%. The method was successfully applied to analyze chilli product sample. [ABSTRACT FROM AUTHOR]

Illicit use of Sudan dyes, a group of harmful and carcinogenic azo dyes, in the food industry has taken a surge in various parts of the world, especially in Africa. Their use in food as additives pose a dire health risk to consumers and have been banned by various food regulatory bodies worldwide. To help increase surveillance, various methods have been proposed for their analysis in literature. This study also sought to experiment and propose an alternative method for quick, easy, cheap, robust and ecologically safe analysis of Sudan dyes in chilli pepper powder and similar matrices. The optimized method used a 6.0 mL mixture of acetone:acetonitrile (1:5 v/v) solvent in a modified QuEChERs method for extraction of Sudan dyes I-IV. The simultaneous analysis of the dyes were achieved on Shimadzu prominence UFLC 20AD coupled with SPD 20AX UV detector operated at dual wavelength of 500 and 480 nm. A total of twenty four (24) chilli pepper powder samples from eight different vendors on the Ghana market were analysed using the optimized method. Quantitation of analytes were done using the external standard calibration method with determination coefficient, R2 > 0.9999. The limit of detection (LOD) and limit of quantitation (LOQ) of the method were 0.02–0.04 mg/kg and 0.05–0.13 mg/kg respectively. A good recovery range between 85.3 – 121.2% were obtained for a spike level of 1.0 mg/kg in real samples. ANOVA analysis at 95% CL showed statistically no significant difference (p > 0.05) in the recoveries between samples and also between the individual compounds. The method experimented and proposed in this study is fast, easy, cheap, robust and ecologically safe, presenting an alternative method for routine analysis for increased rate of surveillance against the illicit use of Sudan dyes as food additives.

A tryptophan ionic liquid (TrpIL) decorated magnetic graphene oxide (Fe3O4@SiO2-GO-TrpIL) nanocomposite has been prepared for magnetic solid-phase extraction of Sudan I–IV before their high performance liquid chromatography (HPLC) analysis. Fe3O4@SiO2 nanoparticles loaded on graphene oxide endow the as-prepared nanocomposite with superparamagnetic performance, benefiting conveniently magnetic separation of the Sudan-absorbed nanocomposites from an aqueous phase. Both TrpIL and grapheme oxide make the Fe3O4@SiO2-GO-TrpIL adsorbent possess high affinity and extraction efficiency toward target analytes, Taking full advantages of the adsorbent, each of Sudan I–IV could be accurately quantified in a linear range of 0.01–0.50 µg mL−1 with the detection limit of 1.0 ng mL−1 under the optimized conditions. A 10-fold enrichment factor was obtained. The present method was employed for the simultaneous determination of Sudan I–IV in chill and water samples with satisfactory results. The thermodynamic and kinetic investigations proved that the targets might be chemisorbed onto the Fe3O4@SiO2-GO-TrpIL nanocomposite. [ABSTRACT FROM AUTHOR]

Layered double hydroxides are a family of inorganic crystals that have gained a lot of attention due to its special structure and properties such as high porosity, large specific area, and excellent anion exchange ability. In this work, flower‐like NiAl‐layered double hydroxides with high specific area were in situ immobilized onto the stainless steel fibers by bioinspired polydopamine modification method and packed into poly (ether ether) ketone tube for online solid‐phase microextraction with high performance liquid chromatography analysis. Thanks to the high specific surface area and excellent extraction ability of the NiAl‐layered double hydroxides, the fibers showed excellent extraction performance to three Sudan dyes with enrichment factors between 260 to 650 folds. After optimization of the reaction and extraction conditions, an online solid‐phase microextraction method was developed for determination of Sudan dyes in water samples and chili samples. The method has limits of detection of 0.01 to 0.02 ng/mL, good linearity and good reproducibility (≤1.45%). [ABSTRACT FROM AUTHOR]

Introduction: The paper presents the method of simultaneous determination of 10 illegal azo dyes in feed by ultra-high performance liquid chromatography coupled with tandem mass spectrometry technique. Material and Methods: The dyes were extracted with hexane, evaporated to dryness, and analysed. Separation was achieved in 7 min in a gradient elution using acetonitrile (A) and 0.1% formic acid (B) as a mobile phase. Results: The validation results showed the repeatability of the method, which was evaluated at three levels (50, 500, and 5,000 μg/kg). All the matrix calibration curves for the working ranges were linear (R2 0.9904 to 1.0), the repeatability was between 2.1% and 24%, and recoveries ranged from 77.9% to 120%. The LOD and LOQ were at 1-2 and 5-10 μg/kg for different dyes, respectively. Furthermore, the method was applied in the homogeneity tests of the in-house prepared feed containing Sudan I at the levels of 0.5, 5, and 50 mg/kg. Conclusions: A sensitive, selective, and fast multiresidue method was successfully developed and validated. Its robustness was confirmed by the analysis of an experimental feed containing Sudan I.

• A novel solidified floating organic drop microextraction was developed for Sudan dyes. • Ultrasound was used for green sample preparation and the UAEME-SID-SFOD method. • The proposed UAEME-SID-SFOD method does not need a disperser solvent and centrifugation step. • The proposed method is simple, rapid, cost-effective, and environmental friendly. This study aimed to analyze the presence of Sudan I–IV in chili products using high performance liquid chromatography and summarized the data performance after ultrasound-assisted emulsification microextraction and salt-induced demulsification with solidified floating organic drop (UAEME-SID-SFOD). After demulsification, the low density solvent was floating instantaneously solidified in an ice-bath; any remaining liquid phase was removed. The solidified part was quickly melted at room temperature and used for analysis. Parameters such as linearity (0.5–2500 ng mL−1, R 2 ⩾ 0.999), limits of detection (0.16–0.24 ng mL−1), and limits of quantification (0.53–0.80 ng mL−1) were used to validate this method. The pre-concentration factor for the 5 mL sample solution was 62. Under optimum conditions, the recoveries ranged between 91% and 107%, with relative standard deviations ranging from 1.8% to 3.5% for intra-day (n = 7) and 4.8% to 6.3% for inter-day (n = 5 × 3) analyses. This novel proposed method has great potential applications in most analytical laboratories that use general instrumentation. This method is easy, rapid, and environmentally friendly. In addition, it does not use any disperser solvent and can eliminate the centrifugation step for aqueous and organic phase separation. Therefore, it is expected that the UAEME-SID-SFOD would be a useful method for various analytical sample extraction purposes. [ABSTRACT FROM AUTHOR]

Spices are added in order to enhance the organoleptic characteristics of food and culinary dishes, making them more attractive for consumers. The use of illicit cheap colourants might be profitable along the food supply chain, posing undue risks to human health. This work evaluates the feasibility of NIR spectroscopy with chemometrics as a rapid, simple, non-destructive and affordable screening tool to determine the presence of Sudan I, II, III, IV and Para-red dyes in paprika. The dataset comprised unadulterated and adulterated samples with the five studied dyes at different concentration levels. Several multivariate classification models were built with Linear Discriminant Analysis (LDA) and different machine learning techniques. Preliminary results show that a classifier based on only six wavenumbers is able to determine the presence of some of these dyes in food samples in levels that may represent risk to human health. Sensitivities and specificities above 90% were obtained in almost all cases. These results show the feasibility of inexpensive and portable devices that can be useful for screening out adulterated stock along the food chain supply. [ABSTRACT FROM AUTHOR]

Highlights • A dummy-template MIP capable of recognizing 7 Sudan dyes was synthesized. • The MIP's recognition mechanism was studied by using computation simulation. • A reusable and ultrasensitive CL sensor was prepared on common microtiter plate. • The assay consisted of only one sample loading step prior to data acquisition. Abstract The objective of this study is to report a molecularly imprinted polymer-based chemiluminescence method for determination of Sudan dyes. A dummy-template molecularly imprinted polymer capable of recognizing seven Sudan dyes was first synthesized and its recognition mechanism was studied by using computation simulation method. The polymer was coated in the wells of conventional microplate to prepare a chemiluminescence sensor and the assay process consisted of only one sample-loading step prior to signal acquisition. The optimized sensor was used to determine the seven dyes in egg yolk and the results were confirmed with a high performance liquid chromatography. Results showed that this sensor achieved ultrahigh sensitivity (1.0–5.0 pg/mL), rapid assay process (10 min) and satisfactory recovery (70.5%–92.2%). Furthermore, the sensor could be reused for 5 times. Therefore, this sensor could be used as a useful tool for screening the residues of Sudan dyes in egg. [ABSTRACT FROM AUTHOR]

Highlights • Design and preparation of a new nanostructured sensor for detection of Sudan dyes. • Application of multivariate optimization in voltammetric studies. • Combination of DPV and MCR-ALS methods. • Simultaneous detection of Sudan dyes with high overlapping voltammograms. • Sensitive and selective detection of Sudan dyes in real samples. Abstract Multivariate curve resolution-alternating least squares (MCR-ALS) assisted with electrochemical techniques was applied for simultaneous determination of Sudan II and III at a surface of zinc oxide nanoparticles (ZnONPs) modified carbon paste electrode. Characterization of the ZnONPs and the nanostructured modified electrode was performed by X-ray diffraction (XRD), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) techniques. Response surface methodology using central composite rotatable design was employed to design of experiments and achieving to optimum values of variables. For simultaneous determination of Sudan II and III, electrochemical second order data were obtained by changing of pulse height in differential pulse voltammetry technique. MCR-ALS was performed on the data to obtain the decomposition peaks of analytes. Then, the detection limits were obtained 1.87 and 2.62 nM for Sudan II and III, respectively. Finally, this method used for the analysis of the two analytes in real samples. [ABSTRACT FROM AUTHOR]

Two types of magnetically modified porous β-cyclodextrin polymers (PCDPs) were successfully synthesized. The first type, named MPCDPs(C), was fabricated by co-precipitating PCDPs with Fe3O4, resulting in a Brunauer–Emmett–Teller (BET) surface area of 106.68 m2 g−1. The second type, named MPCDPs(M), was fabricated by grafting PCDPs onto the surface of magnetic microspheres, resulting in a BET surface area of 34.63 m2 g−1. Both MPCDPs were found to enable effective extraction and separation of Sudan dyes from foodstuffs and environmental water. Coupled with high-performance liquid chromatography, the limits of detection for Sudan dyes were in the range of 0.013–0.054 ng mL−1 with MPCDPs(C), and 0.028–0.039 ng mL−1 with MPCDPs(M). Recoveries were between 85.8 and 102.8% for spiked food samples and 88.3 and 103.2% for spiked water samples, suggesting that the developed methods are promising for accurate quantification of Sudan dyes at trace levels in foodstuffs and environmental water. [ABSTRACT FROM AUTHOR]

Food colorants are inalienable part of human life. Since ancient times, they have become firmly established and have undergone a number of changes. During this time, the attitude towards them has changed. The desire to color the food now raises questions about the various side effects of their use. With the development of methods of toxicology and obtaining data on the toxicity of food coloring, restrictions and standards for their content in food have emerged. The development of methods for the analysis of dyes in various food products is becoming increasingly in demand. Development of screening immunoanalytical methods such as enzyme-linked immunoassay and immunochromatographic one suitable for simultaneous analysis of a large number of samples at the same time allows to avoid serious costs when operating the chromatographic equipment. Reduction of the analysis time and simple sample preparation is what unites immunoassay techniques. This review shows the possibilities of modern immunoanalytical methods for analyzing samples and determining food dyes belonging to different classes. [ABSTRACT FROM AUTHOR]

Abstract Two strategies based on multivariate qualitative and quantitative analysis are proposed for determining whether paprika samples are adulterated with Sudan I or II dyes. The samples were characterized by their UV–visible spectrum. Then, the following chemometric techniques were applied: principal component analysis (PCA) for the data exploration stage, partial least squares-discriminant analysis (PLS-DA) for the qualitative strategy and partial least squares (PLS) for the Sudan quantification strategy. Three classes were considered in the qualitative analysis: unadulterated, adulterated with Sudan I and adulterated with Sudan II. For the quantitative analysis, models were developed for each adulterant in a concentration range of 0–12 mg g−1, where 0 mg g−1 stands for the unadulterated samples. Both strategies gave satisfactory results. The multi-class PLS-DA model properly differentiate between the three types of studied samples: non-adulterated and adulterated with Sudan I and with Sudan II. Only samples at the lowest concentration (1 mg g−1) were wrongly detected as unadulterated. The PLS models were validated by setting the regression line of the model-predicted concentration versus the real concentration for the test set samples. The slope and intercept of each regression line were compared with those of the ideal line (0, 1) by means of the joint test of ordinate and slope. Highlights • Detection of paprika adulteration with Sudan I and II dyes by UV-Visible spectroscopy and multivariate analysis • Qualitative (PLS-DA classification) and quantitative (PLS calibration) strategies were compared • PLS-DA had good performance to differentiate between the unadulterated and both adulterated classes (Sudan I and II) • Only samples at the lowest concentration (1mg/g) of adulterant were classified as unadulterated • PLS model was validated by applying the joint test to the regression line of the model-predicted vs the real concentrations. [ABSTRACT FROM AUTHOR]

Copyright of Food Research & Development is the property of Food Research & Development Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Herein a facile method for immobilization of zeolitic imidazolate frameworks (ZIFs) was developed. The ZIFs grew on electrochemically deposited zinc oxide (ZnO) layer while carbon fiber bundle served as substrate. The synthesized ZIFs-ZnO composite was packed into PEEK tube as sorbent for online solid phase microextraction (SPME)-HPLC-UV analysis of Sudan dyes. Good enrichment efficiency (200–461 fold), low limits of detection (0.002 ng mL−1) and wide linear ranges (0.02–20 ng mL−1, correlation coefficient > 0.9996) were achieved. The analytical method was demonstrated to be practical for analysis of Sudan dyes in environmental water samples with good recoveries (83.5%~95.0%). Graphical abstract Facile immobilization of zeolitic imidazolate framework on electrochemically deposited zinc oxide layer was achieved while the zinc oxide creatively acted as bridge between carbon fiber bundles and the zeolitic imidazolate framework. The modified carbon fiber bundles were packed into PEEK tube loop and connect with HPLC system for online solid-phase microextraction. Good extraction efficiency (between 200 and 461 fold) for Sudan dyes showed with the system. Application in spiked water samples exhibits high extraction efficiency and good recoveries. The feasible method is efficient and promising to introduce other metal-organic framework as efficient sorbent for online solid-phase microextraction. fx1 Highlights • Carbon fiber bundles with composite coating possess high extraction efficiency. • Facile introduction of zeolitic imidazolate framework as selective sorbent. • The zinc oxide acted as bridge between ZIFs and carbon fiber bundles. • Sudan dyes were efficiently extracted in acqueous solution. • A promising method to introduce other metal-organic frameworks as sorbent. [ABSTRACT FROM AUTHOR]

Throughout the years, azo compounds including Sudan dyes have been widely used in industry as colorants in food, cosmetics, waxes, solvents, textiles, plastics and printing inks. Sudan dyes I, II, III, IV, and their degradation products have been regarded to hurt human health. They cause cancer due to their teratogenicity, genotoxicity and carcinogenicity effects. In the present work, the efficiency of ferrous sulfate with low cost and the first choice in the treatment of printing, dyeing and electroplating wastewater to reduce the toxicity of Sudan II-induced oxidative damage to hematological parameters, liver and kidney functions in adult female and male rabbits was investigated. Animals which received Sudan II were treated with ferrous sulfate as the sole source of potent liquid for 14 days at the dose of 111mg/kg B.wt before being sacrificed. Hematological parameters (total leukocytes (WRBs), erythrocytes (RBCs) count hemoglobin content (Hb) and hematocrit percentage (Ht%), liver and kidney functions were done to check the efficiency of ferrous sulfate as Sudan II detoxification. The obtained data clearly showed that Sudan II toxicity led to a significant reduction in (WBCs, RBCs, Hb, and Ht) of the hematological parameters. Sudan II led to an elevation in the activity of liver function enzymes (transaminase; ALT and AST), a decrease in Alkaline phosphatase ALP and an increase in kidney functions (urea and creatinine). The detoxification properties of ferrous sulfate were obvious thanks to good flocculation and decolorization, utilized to separate heavy metal ions, oils, phosphorus and forpurification, and wastewater. Finally, the present study proved that Sudan II treated with ferrous sulfate can keep hematological parameters, liver and kidney functions near the physiological normal state. [ABSTRACT FROM AUTHOR]

Abstract An easy performed surfactant-mediated microextraction approach using switchable hydrophilicity solvent was proposed for the sample pretreatment of solid food samples. The procedure included mixing of solid food sample and aqueous solution of sodium hexanoate provided a micellar solution formation. By this sample pretreatment step, the hydrophobic analytes were extracted into the micellar solution. The injection of sulfuric acid solution into the sample suspension decreased the pH value of the aqueous phase and as a result promoted the hexanoic acid phase formation and final phase separation from the sample suspension. The performance of the suggested approach was demonstrated by the HPLC-UV determination of Sudan dyes (Sudan I, Sudan II and Sudan III) in spiked salted salmon and spices powder samples. This analytical task was used as a proof-of-concept example. The LOD values, calculated from the blank tests based on 3σ, were 0.15 μmol L−1 (0.19 mg kg−1), 0.02 μmol L−1 (0.028 mg kg−1) and 0.10 μmol L−1 (0.18 mg kg−1) for Sudan I, Sudan II and Sudan III, respectively. The sample pretreatment time was 25 min. The proposed method has advantages in comparison with previous developed methods for Sudan dyes determination due to the low consumption of extraction solvent and simplicity of sample pretreatment steps. The developed method can be applied for hydrophobic analytes microextraction from various solid samples (pharmaceutical, food, soil samples, etc.). Graphical abstract Unlabelled Image Highlights • Surfactant-mediated microextraction approach using switchable hydrophilicity solvent • Medium chain fatty acid as switchable hydrophilicity solvent for solid food sample analysis • Surfactant-mediated microextraction approach coupled with HPLC-UV • Determination of Sudan dyes in food samples using switchable hydrophilicity solvent [ABSTRACT FROM AUTHOR]

A multivariate qualitative method using UV-visible spectroscopic data and a PLS-DA chemometric treatment was proposed to identify whether paprika samples were adulterated with Sudan I and Sudan IV dyes, or their mixtures. The method was validated by calculating the main performance parameters (sensitivity and specificity) and determining the stability over time. Three classes were defined: unadulterated samples (class 1), samples adulterated with Sudan I (class 2) and samples adulterated with Sudan IV (class 3). A total of 81 samples belonging to these classes were analyzed. There was also an additional data set consisting of 54 samples adulterated with a mixture of two dyes at two different concentration levels, which were analyzed and predicted with the established models. In addition, all 135 samples were analyzed at different times over a 6-month period to study the model's stability over time. In general, the main performance parameters were very satisfactory. As far as training samples is concerned, sensitivity was 100% for the three classes studied. And specificity was 100% for the unadulterated class and for the adulterated with Sudan IV class, and slightly lower (96%) for the adulterated with Sudan I class. Regarding samples from the additional set, excellent specificities were obtained because no samples were assigned to the unadulterated class. In addition, sensitivity was close to 100% for the Sudan IV class and around 75% for the Sudan I class. All the main performance parameters were maintained throughout the 6 months of the study. [ABSTRACT FROM AUTHOR]

Food authenticity and food safety are of high importance to organizations as well as to the food industry to ensure an accurate labeling of food products. Respective analytical methods should provide a fast screening and a reliable cost-efficient quantitation. HPTLC was pointed out as key analytical technique in this field. A new HPTLC method applying caffeine-impregnated silica gel plates was developed for eight most frequently found fat-soluble azo dyes unauthorizedly added to spices, spice mixtures, pastes, sauces, and palm oils. A simple post-chromatographic UV irradiation provided an effective sample cleanup, which took 4 min for up to 46 samples in parallel. The method was trimmed to enable 23 simultaneous separations within 20 min for quantitation or 46 separations within 5 min for screening. Linear (4-40 ng/band) or polynomial (10-200 ng/band) calibrations of the eight azo dyes revealed high correlation coefficients and low standard deviations. Limits of detection and quantification were determined to be 2-3 and 6-9 ng/zone, respectively. After an easy sample extraction, recoveries of 70-120% were obtained from chili, paprika, and curcuma powder as well as from chili sauce, curry paste, and palm oil spiked at low (mainly 25-50 mg/kg) and high levels (150-300 mg/kg). For unequivocal identification, the compound in a suspect zone was eluted via a column into the mass spectrometer. This resulted in the hyphenation HPTLC-vis-HPLC-DAD-ESI-MS.Simplified clean-up by UV irradiation for Sudan dye analysis in food by HPTLC-vis-HPLC-DAD-ESI-MS. [ABSTRACT FROM AUTHOR]

In the present work, we describe an efficient filter-based microextraction method with a proper sample clean-up for the simple determination of the banned Sudan dyes (I, II, III, and IV) in the foodstuff and water samples. The method is based upon the dispersion of a low-toxic solidifiable organic solvent (1-undecanol, 75 μL) into an aqueous sample solution and utilization of a syringe filter for the emulsion breaking. This syringe filter with a nylon membrane is compatible with a broad range of solvents and thus is ideal for the rapid filtration of most aqueous and organic solutions. Hence, along with the passage of a mixture of an aqueous sample solution and an organic solvent through the membrane, fine droplets of the extractant solvent are aggregated, separated from the aqueous sample solution. By implementing this simple method, the overall extraction time is just 3-4 min; it is environmentally friendly and centrifuge-free, and it provides a high sample clean-up by filtration of the acceptor phase. The parameters influencing the extraction efficiency including the type and volume of the extraction solvent, pH, ionic strength, and number of extractions are thoroughly examined and optimized. Under the optimal experimental conditions, the proposed method provided a good linearity in the range of 1.0-1500 ng mL−1, good extraction repeatabilities (relative standard deviations below 8.9%, n = 5), low limits of detection (0.2-0.7 ng mL−1), and enrichment factors of 105-138. [ABSTRACT FROM AUTHOR]

Development of stir bar sorptive extraction (SBSE) device with high stability and extraction efficiency is critical and challenging by date. In this work, etched poly(ether ether ketone) (PEEK) tube with high mechanical strength and large specific surface area was used as jacket for SBSE device. By etching with concentrated sulfuric acid, the smooth outer surface of PEEK become porous with plenty of micro holes, which was beneficial for coating of sorbents and significantly improved the extraction performance. After functionalized by bio-polydopamine method, strong hydrophobic p-naphtholbenzein molecular was immobilized onto the chemical resistant PEEK surface (PNB@E-PEEK) as stationary phase. We also firstly developed a simple detachable dumbbell-shaped structure for improving the workability of PEEK jacket stir bar. The dumbbell-shaped construction can eliminate the friction between stir bar and container, and the design of detachable structure make elution can be accomplished easier with small amount of organic solvent. It was interesting that the developed detachable dumbbell-shaped PNB@E-PEEK stir bar showed exceptional stability and extraction efficiency for SBSE enrichment of multiple analytes including several Sudan dyes, triazines, polycyclic aromatic hydrocarbons (PAHs), alkaloids and flavonoid. By coupling with high performance liquid chromatography-ultraviolet detection (HPLC-UV), PNB@E-PEEK stir bar based SBSE-HPLC-UV method was applied for the analysis of common Sudan dye pollutants. The method showed low limits of detection (0.02-0.03 ng/mL), good linearity (R 2  ≥ 0.9979) and good reproducibility (relative standard deviation ≤ 7.96%). It has been successfully applied to determine three dye pollutants in tap and lake water. [ABSTRACT FROM AUTHOR]

There has been an increasing demand for rapid and sensitive techniques for the identification of Sudan compounds that emerged as the most often illegally added fat-soluble dyes in herbal medicine. In this report, we have designed and fabricated a functionalized filter paper consisting of gold nanorods (GNRs) and mono-6-thio-cyclodextrin (HS-β-CD) as a surface-enhanced Raman spectroscopy (SERS) substrate, in which the GNR provides sufficient SERS enhancement, and the HS-β-CD with strong chemical affinity toward GNR provides the inclusion compound to capture hydrophobic molecules. Moreover, the CD-GNR were uniformly assembled on filter paper cellulose through the electrostatic adsorption and hydrogen bond, so that the CD-GNR paper-based SERS substrate (CD-GNR-paper) demonstrated higher sensitivity for the determination of Sudan III (0.1 μM) and Sudan IV (0.5 μM) than GNRs paper-based SERS substrate (GNR-paper), with high stability after the storage in the open air for 90 days. Importantly, CD-GNR-paper can effectively collect the Sudan dyes from illegally adulterated onto samples of Resina Draconis with a simple operation, further open up new exciting opportunity for SERS detection of more compounds illegally added with high sensitivity and fast signal responses. [ABSTRACT FROM AUTHOR]

In this work, a novel method, namely centrifugeless dispersive liquid-liquid microextraction, is introduced for the efficient extraction of banned Sudan dyes from foodstuff and water samples. In this method, which is based upon the salting-out phenomenon, in order to accelerate the extraction process, the extraction solvent (1-undecanol, 75 μL) is dispersed into the sample solution. Then the mixture is passed through a small column filled with 5 g sodium chloride, used as a separating reagent. In this condition, fine droplets of the extraction solvent are floated on the mixture, and the phase separation is simply achieved. This method is environmentally friendly, simple, and very fast, so that the overall extraction time is only 7 min. Under the optimal experimental conditions, the preconcentration factors in the range of 90–121 were obtained for the analytes. Also good linearities were obtained in the range of 2.5–1200 ng mL −1 (r 2  ≥ 0.993). [ABSTRACT FROM AUTHOR]

Hybrid nanostructures composed of γ-Fe 2 O 3 (maghemite) and carboxylated-multi walled carbon nanotube (cMWCNT) were used for the magnetic solid phase extractions and determination of Sudan I, II, III, IV, Para Red, Sudan Black B and Sudan Red 7B in chili products. High performance liquid chromatography (HPLC) was employed for the measurements. Limit of quantification (LOQ) values were found in the range 0.44–2.82 ng mL −1 for analytes. The best extraction parameters were determined as pH 8.0, 40 mg of magnetic nanoparticle, 4.0 min of contact time, 0.3 mL desorption by acetonitrile. The samples were dissolved in acetone-dichloromethane-methanol (3:2:1, v/v/v) and diluted with acetonitrile-methanol (v/v; 80:20) before the method was applied. Concentrations of Sudan dyes and Para Red were determined in four samples of chili powder from less than LOQ to 31.21 ± 1.6 ng g −1 , two samples of chili tomato sauces (lower than LOQ) and two samples of ketchup (lower than LOQ). [ABSTRACT FROM AUTHOR]

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Three-dimensional (3D) hierarchical magnetic hollow sphere-like CuFe 2 O 4 (3D HMHS-CuFe 2 O 4 ) were designed to sensitively detect four Sudan dyes combined with HPLC–DAD. The formation mechanism of 3D HMHS-CuFe 2 O 4 is also discussed. Compared to the particle-like CuFe 2 O 4 (PL-CuFe 2 O 4 ), the as-obtained 3D HMHS-CuFe 2 O 4 provided a higher extraction efficiency for the four Sudan dyes (I, II, III and IV) due to its hierarchical hollow structure with properly interconnected pores where the targets can easily diffuse into the reaction sites. Thus, a magnetic solid-phase extraction (MSPE)-HPLC method was established for the simultaneous measurement of the four Sudan dyes. Under optimized conditions, good linearity (5–4000 ng g −1 , r 2 ≥ 0.9991), limits of detection (LODs, 0.56–0.60 ng g −1 ), recoveries (91.1%−99.3%) and precision (RSDs ≤ 4.9%) for the four Sudan dyes were obtained. The proposed MSPE-HPLC-DAD method is a convenient, effective, sensitive and time-saving method for the rapid isolation and determination of four Sudan dyes in preserved bean curd. [ABSTRACT FROM AUTHOR]

• Extraction recoveries were 90.6% and 102.5%. • The UA-SUPRAS-ME method was used for the determination of Sudan I–IV dyes. • The microextraction procedure was performed in as little as 10 min. • The method is both low detection limit and low cost. A new ultrasonically assisted supramolecular solvent-based microextraction (UA-SUPRAS-ME) method has been reported. This technique is one of the green methods for rapid microextraction and determination of Sudan I, II, III and IV dyes from food and beverage samples and the study investigated the effects of various parameters such as centrifugation time, 1-octanol volume, pH, supramolecular solvent type, THF volume, ultrasonication time on the optimization of the microextraction process. Addition and recovery of the method were carried out at two different concentrations (10 and 100 ng mL−1) to food and beverage samples and the accuracy of the method was determined. Sudan I dye was detected in red pepper and hot sauce from food samples. Extraction recovery values were found between 90.6 % and 102.5 % which are promising compared to many other methods. [ABSTRACT FROM AUTHOR]

A new approach applying a pet fish air pump is introduced to develop an extraction method, namely, air-pump-enhanced emulsion, followed by salt-assisted emulsion breaking based on solidified floating organic drop microextraction for the extraction and preconcentration of Sudan I–IV before high-performance liquid chromatography. The applicability of this method was successfully demonstrated by determination of these dyes in four chili products that include chili powder, chili oil, chili sauce, and chili paste. An enrichment factor of 62 was obtained only with a sample solution of 5 mL. A linear range of 0.5–2500 ng/mL was obtained with a limit of detection of 0.16–0.24 ng/mL and recovery of 90–110%. This method is superior to other liquid–liquid extraction methods, as is simple, rapid, environmental friendly, and its phase separation needs no centrifugation. It also needs no disperser solvent and requires less organic solvent, and satisfies the criteria to be called as a green extraction. Therefore, this facile extraction method can be successfully applied in the determination of Sudan dyes in food samples. [ABSTRACT FROM AUTHOR]

The mechanisms of the toxicity of Sudan dyes to the key antioxidant enzyme catalase (CAT) were investigated by spectroscopic methods, calorimetry techniques, enzyme activity assay, and molecular docking. Results showed that Sudan dyes bound to CAT through hydrophobic force, which changed the microenvironment of tryptophan and tyrosine residues, leading to a conformational alteration and shrinkage of the protein. Enzyme activity assay and molecular docking revealed that the activity of CAT was slightly inhibited in the presence of Sudan dyes. In comparison, the binding of Sudan II with CAT was slightly stronger than Sudan IV. Also, Sudan II and Sudan IV showed a different impact on the microenvironment of aromatic amino acid residues. But the dyes had very similar effects on conformation and activity of the protein. This work provides an essential reference for the evaluation of Sudan dyes' effects on body's antioxidant defense system and safe use of Sudan dyes. [ABSTRACT FROM AUTHOR]