Sudan Red 7B Research Articles

Prediction model for retention volumes of the three-phase solvent system in high-speed countercurrent chromatography.

Owing to its ability to separate substances with a broad scope of polarities, exploring the three-phase solvent systems (TPSSs) with high-speed countercurrent chromatography is a topic of interest in separation science, and their retention volumes should be more concerned. This study primarily investigates the behavior of retention volumes while examining the isolation abilities of the TPSS in the technique above. We took standard compounds, including sophoricoside, Sudan red 7B, and rotenone, which have a broad range of polarity, for investigation in this study and separated them using different four-liquid TPSSs made up of water, acetonitrile, methyl acetate, and n-hexane (WAMH). Our findings show that the retention volumes gradually alter in response to changes in phase polarity within the proposed solvent systems. With TPSSs, we preliminarily studied compound isolation and the promising formula of their retention volumes. The proposed solvent systems WAMH in different ratios showed high correlations and adjusted correlation coefficients above 0.9978 and 0.9913 for the actual and calculated retention volumes. This study will be particularly beneficial for researchers focusing on countercurrent chromatography with TPSSs, as it offers valuable time-saving insights.

Validation and measurement uncertainty of analytical methods for various azo dye adulterants in Curcuma longa L.

Food adulteration involving the illegal addition of dyes to foodstuffs has become an alarming issue in recent years. This study developed and validated a high-performance liquid chromatography (HPLC)-DAD (diode array detector) method for the simultaneous determination of nine azo dyes (Butter Yellow, Sudan Orange G, Para Red, Sudan I, Sudan II, Sudan III, Sudan IV, Sudan Red 7B, and Scarlet 808). Moreover, a qualitative analysis method using liquid chromatography-tandem mass spectrometry was developed to more accurately identify peaks detected in HPLC-DAD. The calibration curve represented good linearity (r2≥0.9998) over the measured concentration range of 0.5-25mg/kg. limit of detection and limit of quantification were 0.01-0.04 and 0.04-0.12mg/kg, respectively. Accuracy and precision were 96.0-102.6 and 0.16-2.01 (relative standard deviation%), respectively. Additionally, the measurement uncertainty and HorRat value were estimated. Several Curcuma longa L. distributed in Korea were collected and monitored for azo dye contaminants. PRACTICAL APPLICATION: The proposed HPLC-DAD method represents a significant advancement in the field, offering a reliable means of quantifying azo dyes and identifying their presence even at trace levels in adulterated turmeric. This not only contributes to ensuring the safety and integrity of turmeric products but also establishes precedent for robust analytical techniques in addressing food safety challenges.

Simultaneous determination and extraction of illegal dyes Sudan orange G and Sudan red 7B using ultrasonic assisted dispersive liquid–liquid microextraction based on deep eutectic solvent followed by derivative UV-VIS spectrophotometry

An ultrasonic-assisted dispersive liquid–liquid microextraction based on deep eutectic solvent was utilised for simultaneous preconcentration and determination of illegal dyes Sudan orange G (SOG) and Sudan red 7B (SR7B) using second derivative ultraviolet spectrophotometry. Under optimised conditions, the limit of detection (0.014 and 0.011 μg mL−1) and linear dynamic range (0.036–0.900 and 0.030–1.000 μg mL−1) with high determination coefficient of 0.9916 and 0.9937 were obtained for SOG and SR7B, respectively. The relative standard deviations of method (n = 3) for intra- and inter-day were obtained as 3.5% and 10.5% for SOG and 5.0% and 9.0% for SR7B. The preconcentration factor for both dyes was calculated as 75 for all experiments. The applicability of the proposed method was investigated in different real samples, including in chilli powder, lipstick, river water and also in well water. A relative recovery percentage of 88–114% was obtained for these samples. Effect of interferences for the model solutions was also examined wherein satisfactory results confirm reasonable selectivity of the proposed method.

Determination of banned dyes in red spices by ultra-high-performance liquid chromatography-atmospheric pressure ionization-tandem mass spectrometry

This paper reports the development of an ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC‒MS/MS) method to determine eight banned dyes (Sudan I-IV, Sudan Orange, Sudan Red 7B, Para Red, Rhodamine B) in turmeric, curry, and chili products. For this purpose, the feasibility of electrospray (ESI), atmospheric pressure chemical ionization (APCI) and atmospheric pressure photoionization (APPI) for the ionization of these compounds was evaluated. The tandem mass spectrometry (MS/MS) fragmentation of all targeted compounds was studied and both multistage mass spectrometry and high-resolution mass spectrometry were used to establish the fragmentation pathways and identify common fragmentation behaviors. Among the most significant ions, the most characteristic and abundant product ions observed on the triple quadrupole were selected to propose a selective and sensitive UHPLC‒MS/MS method (multiple reaction monitoring mode, MRM) of these target compounds in spices samples after a quick and easy extraction with acetonitrile. Matrix effect (ME) studies carried out in the three atmospheric pressure ionization sources have demonstrated that APCI showed the best performance with ME values ranging from 2 to 25%. Furthermore, the estimated quality parameters indicated the good performance of the proposed method, providing low method limits of detection (MLODs) (1–48 μg kg−1), good intra-day precision (RSD % < 15%), and accurate quantitation (relative error % < 15%). Finally, the applicability of the developed method was demonstrated by the analysis of turmeric, curry, and chili products. In total, 36 diverse samples coming from different countries were analyzed and although none of these compounds were detected above the MLODs, the analysis of spiked samples showed that the method was able to detect this family of compounds at low μg kg−1.

UiO-66 metal-organic frameworks/gold nanoparticles based substrates for SERS analysis of food samples

Recently, metal-organic frameworks (MOFs) based substrates have shown great potential for the quantitative analysis of food samples by surface-enhanced Raman scattering (SERS) due to their unique properties. Herein, we developed two UiO-66 MOFs/gold nanoparticles (AuNPs) based substrates by self-assembly, including UiO-66/AuNPs suspension substrate and UiO-66(NH2)/AuNPs/Nylon-66 flexible membrane substrate, for quantitative analysis of complex food samples by SERS. UiO-66/AuNPs suspension substrate was prepared for SERS-based determination of a carcinogenic heterocyclic amine in barbecue meat. UiO-66(NH2)/AuNPs/Nylon-66 membrane substrate was fabricated for the simultaneous separation, enrichment, and in situ analysis of Sudan Red 7B in chilli products. The heterocyclic amine and Sudan dye in real samples could be detected and quantified with the recoveries of 82.3–110% and 84.5–114% and relative standard deviations (RSDs) of 3.1–11.0% and 1.9–5.6% (n = 3) by use of these two substrates, respectively. These two UiO-66/AuNPs based substrates combined molecular enrichment and SERS activity, achieving excellent analytical accuracy and widening SERS application in practical food safety analysis.

A Fast and Simple Method for the Determination of 12 Synthetic Dyes in Spicy Foods by UHPLC-HRMS

A simple and rapid method for the simultaneous determination of 12 banned fat-soluble synthetic colorants (Sudan I–IV, Sudan black B, Sudan orange G, Sudan red 7B, Sudan red B, Sudan red G, butter ...

Laboratory Evaluation of the Marking Effect of Sudan Red 7B on Subterranean Termites (Reticulitermes speratus) in Republic of Korea

The dye marker Sudan Red 7B was tested as an effective and appropriate marking method for searching the territory of the termite, Reticulitermes speratus, in Korea. The sensitivity of termites to the dye marker was evaluated by measuring the feed consumption amount, survival rate, retention time, and transfer efficiency of R. speratus according to the concentration and feeding period of Sudan Red 7B. As the concentration conditions of dye marker increase, Sudan Red 7B remarkably reduced the feed consumption of the termites. The survival rate was not significantly different from that of the control group (more than 90%), except when feed containing 1% or 2% concentrations of the dye marker was given for five days. The duration of the marking effect persisted for seven days, even at a concentration of 2% dye marker in the feed. No dye transfer by trophallaxis occurred between termites marked with Sudan Red 7B and unmarked termites.

Development of magnetic porous carbon nano-fibers for application as adsorbents in the enrichment of trace Sudan dyes in foodstuffs

A novel kind of magnetic porous carbon nano-fibers (Fe3O4@P-CNFs) materials was successfully prepared and used as an adsorbent. Based on the above-mentioned adsorbent, a simple and effective magnetic disperse solid-phase extraction (MSPE) method was developed and first utilized to the enrichment and purification of five Sudan dyes (including Sudan I, Sudan II, Sudan III, Sudan IV, and Sudan Red 7B) in foodstuffs for the first time. High-performance liquid chromatography was used to determine the content of the Sudan dyes. The parameters affecting the extraction performance were studied and optimized, including the amount of the adsorbent and inorganic salt, type and the volume of the eluent, pH of the sample solution and extraction time. Under the optimized experimental conditions, the results show that the proposed method has a good linear relationship (r≥ 0.9993). The limits of detection range from 0.88 μg L−1 to 1.27 μg L−1. The recoveries range from 86.6% to 99.7% with the relative standard deviations ranging from 0.6% to 7.9% in the methodology validation. The above-mentioned results indicate that the proposed method is a sensitive and reliable procedure with good reproducibility for the detection of Sudan dyes residues in foodstuffs.

Investigation of photo- and thermal isomerization pathways of azobenzene derivative in photostationary state generated by two-color excitation

The reaction pathways for photo- and thermal isomerization in the photostationary state of Sudan red 7B (SR7B), which has two azo groups in its molecule, were examined by a laboratory-designed two-dimensional millisecond time-resolved transient absorption spectrometer that utilizes two-color cw lasers (532 nm and 650 nm) as pump and a white light as probe. The temporal population behavior of four isomeric forms after the two-color pump lasers were simultaneously switched off was monitored in terms of transient absorption change with the time resolution of 50 ms. It was found that, in the photostationary state generated by the two-color pump scheme, the two-color two-step photoisomerization process and the multistep thermal isomerization processes occurred. The reaction rates of the thermal isomerization processes were also determined. Based on the results, we constructed a framework for the reaction pathway network in the photostationary state of SR7B under two-color cw excitation.

Fast and simple method for the detection and quantification of 15 synthetic dyes in sauce, cotton candy, and pickle by liquid chromatography/tandem mass spectrometry

A simple and sensitive liquid chromatography/tandem mass spectrometry (LC-MS/MS) method for the simultaneous determination of 15 illegal dyes (Sudan I, Sudan II, Sudan III, Sudan IV, Sudan Red G, Sudan Orange G, Sudan Red 7B, Para Red, Dimethyl Yellow, Rahodamine B, Sudan Black B, Sudan Red B, Auramine O, Toluidine Red and Orange II) was developed and validated in sauce, cotton candy, and pickle. The samples were extracted with acetonitrile without the use of solid-phase extraction cartridges. Chromatographic separation was achieved on a Zorbax Eclipse Plus C18 column with a flow rate of 500 µL/min at 45 °C, using a gradient elution with A (10 mM ammonium formate in water with 0.1% formic acid) and B (10 mM ammonium formate in acetonitrile (ACN) with 0.1% formic acid) as the mobile phase. The detection was performed on a AB Sciex 6500 Qtrap mass analyzer under multiple reaction monitoring mode. Limit of detection, quantification, linearity, and precision were determined during the validation process. Recoveries ranged from 82% to 119% for all synthetic dyes, in exception to Orange II in cotton candy and pickle, where signal was suppressed due to high matrix interference and poor ionization. This method offers a simple and rapid approach to detect and quantify prohibited dyes in foodstuff that can be utilized in food contaminant laboratories.

Determination of seven illegal dyes in Egyptian spices by HPLC with gel permeation chromatography clean up

Sudan I, II, III, IV, Para Red, Orange G and Red 7B are synthetic regularly dyes utilized to dye plastics and other manufactured materials. In recent years, concerns about the genotoxic possibilities of Sudan colors have been raised. A few national bodies and food experts consider Sudan dyes to be genotoxic cancer-causing agents while others view these dyes as possible cancer-causing agents. Therefore, it is of the outmost importance to assess the risk and presence of Sudan dyes in Egyptian spices, including; sumac, hot chilli, cumin, paprika, curry and turmeric. A total of 83 samples were collected randomly from different supermarkets and spice shop in various municipalities of Egypt (Cairo, Giza, Qalyubia, Faiyum and Alexandria). For Sudan dyes determination, gel permeation chromatography (GPC) and high-performance liquid chromatography (HPLC) were used. Dyes were extracted from spices with acetonitrile and selectively initial separated by GPC. Fractions were collected from 12 min to 24 min and then determined by HPLC with diode array detection (HPLC-DAD). The method performance was validated on hot chilli samples, and the limit of quantification (LOQ) was 0.1 mg/kg for the seven Sudan dyes. Moreover, other method validation parameters were determined in this work, including linearity, accuracy, recovery, limit of detection (LOD), repeatability, reproducibility and expanded uncertainty. Finally, a market survey was conducted to assess the incidence of such illegal dyes and enlighten buyers, almost 50% of the tested samples were contaminated with Sudan dyes. Sudan Red 7B and Para Red were not detected in the samples, and the mean contamination level varied from 0.01 mg/kg for Sudan Ⅱ to 50.1 mg/kg for Sudan Ӏ. It is recommended to buy raw whole spices – not in powder form- and blend them at home. In addition, spices should be purchased from established retailers, and buyers should avoid spices with abnormally red shading.

External Marking and Behavior of Early Instar Helicoverpa armigera (Lepidoptera: Noctuidae) on Soybean

Helicoverpa armigera Hubner (Lepidoptera: Noctuidae) is a pest of major agricultural crops, such as soybean and cotton. A better understanding of larval movement is important for its integrated management and resistance management. Studies with neonates through second instar larvae are still limited by the difficulties involving the handling and observation of these instars. Many studies require marking larvae, and most research involving marking is focused on moths. However, our study investigated aspects of larval behavior of the second instar of H. armigera on soybean plants. The dyes luminous powder red and Sudan Red 7B were tested as external larval markers. Both dyes successfully marked the larvae for most of 1 stadium (48 h) without deleterious effects, and are useful for short-period behavioral studies. Luminous powder red was selected for the H. armigera larval behavior study on soybean because of ease of detection during both day and night. Second instar on-plant movement was consistent, independent of the d period (morning, afternoon, evening). In general, larvae established their feeding site within a few hours of release, and remained feeding on soybean leaves. Second instar behavior suggests that management by nocturnal insecticide application, based on H. armigera larval movement, would not have an advantage over daytime application.

Electrosynthesis of hydrogen peroxide using modified gas diffusion electrodes (MGDE) for environmental applications: Quinones and azo compounds employed as redox modifiers

Although the electrosynthesis of hydrogen peroxide (H2O2) using gas diffusion electrodes (GDE) is a viable option for the production of this oxidizing agent in advanced oxidation processes (AOP) for wastewater treatment, the quest for more efficient electrodes is still regarded a matter of great importance in this area. The present study sought to investigate different redox organic compounds employed as modifiers of carbon black Printex L6 (CP) with the aim of increasing H2O2 production using carbon-based electrodes. Varying amounts of the modifiers, including Sudan Red 7B (SR7B), methyl-p-benzoquinone (MPB), anthraflavic acid (AA) and anthraquinone-2-carboxylic acid (A2CA), were added to carbon black, where the electrochemical activity was studied by applying a microporous catalyst layer on a rotating ring-disk electrode (RRDE). The materials containing 0.5% of SR7B and 5.0% of MPB increased the current efficiency for the electrogeneration of hydrogen peroxide to 86.2% and 85.5%, respectively, compared to 82.8% obtained for unmodified carbon. Carbon Printex L6 gas diffusion electrodes modified with 0.5% of SR7B were studied and the following results were obtained: the application of current density of 75 mA cm−2 led to the production of 1020.1 mg L-1 of H2O2, with an energy consumption of 118.0 kW h kg-1, apparent kinetic constant of 37.34 mg L-1 min-1 and current efficiency of 17.87%. Conversely, the use of GDE with unmodified carbon resulted in the production of relatively less quantity of H2O2 which amounted to 717.3 mg L-1, with more energy consumption of 168.5 kW h kg-1, lower apparent kinetic constant of 21.41 mg L-1 min-1 and lower current efficiency of 12.57%. Based on these results, carbon Printex L6 GDE modified with 0.5% of Sudan Red 7B is seen as a suitable alternative for the production of high amounts of H2O2 which can be applied in advanced oxidation processes in acidic medium.

Screening of Chemical Dyes in Traditional Chinese Medicine by HPTLC-MS.

It has been uncovered that chemical dyes are illegally used in traditional Chinese medicines to brighten color and cover up inferiority, which threaten the safety of patients. In the present study, an HPTLC-MS method was developed for the effective screening of 11 chemical dyes (Sudan I, II, III, and IV; 808 Scarlet; Sudan Red 7B; malachite green; Basic Orange 2; auramine; Orange II; and erythrosine) in traditional Chinese medicine (TCM) raw materials and Chinese patent medicines. Firstly, unwashed HPTLC plates were chosen by comparing the background signals of the TLC plates used directly and prewashed with analytical grade and HPLC grade solvents. Twice developments were conducted to isolate chemical dyes of different polarity. Possible adulterants were preliminarily identified by comparing Rf values and in situ UV-Vis spectra with those of the references. Further confirmation was conducted by tandem MS analysis via an elution head-based TLC-MS interface. Sudan I and IV, 808 Scarlet, and Orange II were successfully detected in eight batches of TCM. The proposed method could be applied as a reliable technology for the screening of chemical dyes in TCM.

Magnetic metal-organic frameworks for fast and efficient solid-phase extraction of six Sudan dyes in tomato sauce

Magnetic solid-phase extraction is an effective and useful technique to preconcentrate trace analytes from food samples. In this study, a magnetic trimeric chromium octahedral metal-organic framework (Fe3O4-NH2@MIL-101) was fabricated and characterized. Fe3O4-NH2@MIL-101 was applied as an adsorbent of magnetic solid-phase extraction combined with high performance liquid chromatography to effectively isolate and simultaneously determine six Sudan dyes (Para Red, Sudan I–IV, and Sudan Red 7B) from tomato sauce. Potential factors affecting the MSPE were investigated in detail, and adsorption efficiency of Fe3O4-NH2@MIL-101 was compared with those of conventional adsorbents, such as neutral alumina, HLB, and C18. The developed method facilitated the extraction with using only 3 mg of adsorbent in 2 min. In addition, enhancement factors of 50, linear range of 0.01–25 μg/mL, and detection limit (S/N = 3) of 0.5–2.5 μg/kg were obtained. The intra-day and inter-day recoveries for spiked Sudan dyes were in the range of 72.6%–92.9% and 69.6%–91.6%, respectively, with relative standard deviations of ≤9.2%.

γ-Fe2O3 magnetic nanoparticle functionalized with carboxylated multi walled carbon nanotube for magnetic solid phase extractions and determinations of Sudan dyes and Para Red in food samples

Hybrid nanostructures composed of γ-Fe2O3 (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 0.44–2.82ngmL−1 for analytes. The best extraction parameters were determined as pH 8.0, 40mg of magnetic nanoparticle, 4.0min of contact time, 0.3mL 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±1.6ngg−1, two samples of chili tomato sauces (lower than LOQ) and two samples of ketchup (lower than LOQ).

Two-dimensional observation of multicolor multistep photoreaction process by using white light excitation covering entire visible region

Abstract Multicolor multistep photoisomerization process of azobenzene derivative in photostationary state was observed by newly developed Fourier transform two-dimensional (2D) spectroscopic technique. The photostationary state was generated by excitation using white light covering the entire visible region, and the photoreaction was monitored by measuring photoinduced bleaching and absorption signals detected by white light probe. The wavelength participating in excitation process for the observed signal was clarified by modulation frequency marked by passing the pump white light through a scanning tandem Fabry-Perot interferometer, and the 2D amplitude and phase spectra were obtained by Fourier transform of the obtained 2D interferogram. By using the system, we succeeded in observing the multicolor multistep process in photoisomerization of Sudan red 7B [1-(4-[Phenylazo]phenylazo)-2-ethylaminonaphthalene, SR7B] that has two azo groups and shows several configurations. It was concluded from the analysis of obtained 2D amplitude and phase spectra that at least two reaction pathways of sequential photoisomerization reactions exist in the photostationary state of SR7B under the white light irradiation. The interpretation is supported by the results of quantum chemical calculations using density functional theory.

Using Factorial Experimental Design To Prepare Size-Tuned Nanovesicles

The aim of this work was to prepare size-tuned nanovesicles using a modified ethanol injection method (EIM) by applying factorial experimental design. Stable size-tuned nanovesicles (liposomes and niosomes) with controlled sizes and high EE values for hydrophobic compounds (Sudan Red 7B and vitamin D3) were achieved. Equations that were able to predict the mean particle sizes, in the ranges of 55–156 nm for liposomes and 224–362 nm for niosomes with PDI values between 0.032 and 0.378, were obtained. These customized soft nanoparticles could be suitable in food, cosmetic, pharmaceutical, or medical applications, such as diagnosis or therapy.

Quantitative Determination of Four Azo Dyes in Rat Plasma with Solid-Phase Extraction and UFLC-MS-MS Analysis: Application to a Pharmacokinetic Study.

A rapid and sensitive ultra-fast liquid chromatography tandem mass spectrometry method, followed by simple protein precipitation and solid-phase extraction, has been developed and validated for the quantitative determination of four azo dyes (Para red, Solvent yellow 2, Solvent red 1 and Sudan red 7B) in rat plasma using D5-Sudan I as the internal standard. The optimal separation was accomplished on an Agilent Eclipse Plus C18 column (100 × 2.1 mm, 1.8 μm) with gradient elution using the mobile phase including acetonitrile and water (containing 0.1% formic acid). The flow rate was 0.45 mL/min. The detection was conducted by means of electrospray ionization mass spectrometry in positive ion mode with multiple reaction monitoring. The calibration curves showed good linearity, with correlation coefficients >0.998 for all of the analytes within the concentration range. The lower limits of quantification (LLOQs) of Para red, Solvent yellow 2, Solvent red 1 and Sudan red 7B in rat plasma were 1.0, 0.1, 0.1 and 0.1 μg/L, respectively. The intra- and interday relative standard deviations were ≤9.6 and ≤12.4%, respectively, and the accuracy was in the range of -5.8 to -9.5%. The average recoveries were between 81.49 and 118.65%, and the matrix effects were satisfactory in the biological matrices. The fully validated method has been successfully applied in measuring levels of the four azo dyes in rat plasma following oral administration of 20.0 mg/kg of analytes in rats, which was suitable for the pharmacokinetic studies of the azo dyes.

Mass Transfer Characteristics of Ozonolysis in Microreactors and Advanced-Flow Reactors

Ozonolysis of alkenes in liquid phase is conducted from micro scales to milli scales using a multichannel microreactor, a Corning low-flow reactor (LFR), and a Corning advanced-flow reactor (AFR). For the mass transfer limited test case of ozonolysis of 1-decene, maximum conversions that depend on the ozone availability in the gas phase are achieved regardless of the operating conditions, proving an excellent mass transfer in all three reactors. Ozonolysis of Sudan Red 7B dye provides visualization of the completion of the reaction in the glass-made AFR and LFR. Overall mass transfer coefficients are estimated to be on the order of 1/s in both the LFR and AFR, increasing with both liquid and gas flow rates. These values are within the same range observed in microchannels and one order of magnitude larger than in other conventional contactors.