Effective extraction and simultaneous determination of Sudan dyes from tomato sauce and chili-containing foods using magnetite/reduced graphene oxide nanoparticles coupled with high-performance liquid chromatography

Metal-organic framework functionalized with deep eutectic solvent for solid-phase extraction of Rhodamine 6G in water and cosmetic products

An NH2 -MIL-53(Al)-DES(ChCl-Urea) nanocomposite was synthesized for extraction and determination of Rhodamine (Rh) 6G from environmental and cosmetic samples. The deep eutectic solvent (DES) was prepared by mixing choline chloride and urea in a mole ratio of 1:2. NH2 -MIL-53(Al)-DES(ChCl-Urea) nanocomposite was synthesized using the impregnation method at a ratio of 60:40 (w/w). The optimum conditions were determined after NH2 -MIL-53(Al)-DES(ChCl-Urea) characterization was performed. The optimum conditions were determined as pH 8, adsorbent amount of 15 mg, total adsorption-desorption time of 6 min, and enrichment factor of 20. The recovery values of the solid-phase extraction method for water and cosmetic samples under optimum conditions were between 95% and 106%. NH2 -MIL-53(Al)-DES(ChCl-Urea) nanocomposite was an economically advantageous adsorbent because of its reusability of 15 times. All analyses were performed using the ultraviolet-visible spectrophotometer. The linear range, limit of detection, and limit of quantification of the method were 100-1000, 9.80, and 32.68 μg/L, respectively. The obtained results showed that the synthesized nanocomposite is a suitable adsorbent for the determination of Rh 6G in water and cosmetic samples. The real sample applications were verified with the high-performance liquid chromatography system.

Multivalent SnO2 quantum dot-decorated Ti3C2 MXene for highly sensitive electrochemical detection of Sudan I in food

A new electrochemical sensor was fabricated by SnO2 quantum dot-decorated Ti3C2 MXene for the highly sensitive detection of Sudan I in food. This sensor with good selectivity, precision and accuracy can be used in monitoring illegal food additives.

Magnetic and thermal dual-sensitive core-shell nanoparticles for highly preconcentration and measurement of Sudan red pollutants

Recently, thermal-sensitive polymers absorbed much more concerns, and the goal of present work was to modify magnetic nanoparticles with N-isopropylacrylamide (NIPAM) and methyl 3,3-dimethylacrylate (DMMA) for obtaining thermal and magnetic dual-sensitive nanoparticles based on silica coated nanoscale zero valent iron and thermal-sensitive polymers (Fe@p(NIPAM-co-DMMA)). Fe@p(NIPAM-co-DMMA) nanoparticles were fabricated and possessed excellent adsorption ability for Sudan pollutants in aqueous samples. A rapid extraction and separation approach utilizing synthesized dual-sensitive nanomaterials was designed and developed before analysis by liquid chromatography (HPLC). Upon the enrichment factors as their optimal values, the established method gained wonderful linearity over the range of 0.05-500 μg L^-1. The precisions of proposed method were all lower than 3.87%. The validating experiments ensured that this developed method provided with satisfied recoveries in the range of 97.4-102.6% from spiked real water samples, which affirmed that this method was a reliable monitoring tool for Sudan pollutants in water and food samples, etc.

Fast, easy, cheap, robust and safe method of analysis of Sudan dyes in chilli pepper powder

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.

Magnetic Solid-Phase Extraction of Organic Compounds Based on Graphene Oxide Nanocomposites

Graphene oxide (GO) is a chemical compound with a form similar to graphene that consists of one-atom-thick two-dimensional layers of sp²-bonded carbon. Graphene oxide exhibits high hydrophilicity and dispersibility. Thus, it is difficult to be separated from aqueous solutions. Therefore, functionalization with magnetic nanoparticles is performed in order to prepare a magnetic GO nanocomposite that combines the sufficient adsorption capacity of graphene oxide and the convenience of magnetic separation. Moreover, the magnetic material can be further functionalized with different groups to prevent aggregation and extends its potential application. Until today, a plethora of magnetic GO hybrid materials have been synthesized and successfully employed for the magnetic solid-phase extraction of organic compounds from environmental, agricultural, biological, and food samples. The developed GO nanocomposites exhibit satisfactory stability in aqueous solutions, as well as sufficient surface area. Thus, they are considered as an alternative to conventional sorbents by enriching the analytical toolbox for the analysis of trace organic compounds.

New approach applying a pet fish air pump in liquid-phase microextraction for the determination of Sudan dyes in food samples by HPLC

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.

Evaluation of a mixed anionic-nonionic surfactant modified eggshell membrane as an advantageous adsorbent for the solid-phase extraction of Sudan I-IV as model analytes

The coadsorption of mixed anionic-nonionic surfactants, sodium dodecylbenzenesulfonate with Triton X-100, on the surface of eggshell membrane was investigated based on adsorption isotherms to improve the solid-phase extraction performance of eggshell membrane toward organic contaminants. Results showed that even though excess Triton X-100 might inhibit the adsorption of sodium dodecylbenzenesulfonate, a low dosage of Triton X-100 can significantly improve sodium dodecylbenzenesulfonate modification and enhance the extraction efficiency of eggshell membrane from 73.7 to 100.4% because of the formation of mixed hemimicelles. The highest recovery was achieved at 2:8 (Triton X-100/sodium dodecylbenzenesulfonate mass ratios), and multiple mechanisms involving π-π interactions, hydrophobic effect, and π-π electron donor-acceptor interactions contributed to the strong extraction affinity. When mixed, the Triton X-100 and sodium dodecylbenzenesulfonate modified eggshell membrane packed cartridge coupled with high-performance liquid chromatography was applied for the simultaneous determination of trace Sudan I-IV, and low detection limits (0.16-0.26 ng/L) were achieved with satisfactory linearity (R²  > 0.999) in 10-10 000 μg/L. For real samples, Sudan II and III in one chilli sauce sample were found at 4.3 and 1.7 μg/kg. Sudan I-IV recoveries at three spiked levels were 87.4-102.9% with precisions <6.8%. Comparison with commonly used solid-phase extraction adsorbents and methods further reflected the superiorities of the proposed adsorbent in sensitivity, retention ability, and applicability.