In situionic-liquid-dispersive liquid-liquid microextraction of Sudan dyes from liquid samples

Temperature-induced dispersive solid-phase extraction as a new approach for preconcentration of Sudan dyes in water and food samples prior to the determination by high-performance liquid chromatography

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%).

Simultaneous capture of hydrophilic and hydrophobic compounds from complex plants by biosurfactant-assisted mechanical amorphous dispersion extraction

A biosurfactant-assisted mechanical amorphous dispersion extraction (BA-MADE) procedure was established for the simultaneous capture of hydrophilic phenolic acids and hydrophobic tanshinones from Salvia miltiorrhiza. Single-factor experiments and the response surface methodology were used to optimize and analyze the crucial parameters for the method, such as the type and amount of amorphous-dispersion extractants, grinding time, extraction time and solid-to-liquid ratio. The optimized parameter values for the BA-MADE process were 407.02 mg of sodium chenodeoxycholate, a grinding time of 4.87 min, an extraction time of 4.92 min, and a solid-to-liquid ratio of 0.5:10 g/mL. The calibration curves of danshensu, rosmarinic acid, lithospermic acid, salvianolic acid B, salvianolic acid A, dihydrotanshinone I, cryptotanshinone, tanshinone I, and tanshinone II A exhibited good linearity in the range of 1-500 μg/mL (R² ≥ 0.9990). The limits of detection of nine analytes ranged from 5.46 to 130 ng/mL, the relative standard deviations (RSDs) of intraday and interday precision were less than 1.95 and 3.56%, respectively, and the recoveries of the real sample were in the range of 85-113%, with RSD% below 3.21%. The BA-MADE method was compared with previously reported methods, such as heating reflux extraction, ultrasonic extraction and microwave-assisted micellar extraction, and the results demonstrated that the developed method has significant advantages in the simultaneous extraction of hydrophilic and hydrophobic active components from Salvia miltiorrhiza.

Preparation of new hydrophobic deep eutectic solvents and their application in dispersive liquid-liquid microextraction of Sudan dyes from food samples

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.

Application of Micro-cloud point extraction for spectrophotometric determination of Malachite green, Crystal violet and Rhodamine B in aqueous samples

A novel, green, simple and fast method was developed for spectrophotometric determination of Malachite green, Crystal violet, and Rhodamine B in water samples based on Micro-cloud Point extraction (MCPE) at room temperature. This is the first report on the application of MCPE on dyes. In this method, to reach the cloud point at room temperature, the MCPE procedure was carried out in brine using Triton X-114 as a non-ionic surfactant. The factors influencing the extraction efficiency were investigated and optimized. Under the optimized condition, calibration curves were found to be linear in the concentration range of 0.06-0.60mg/L, 0.10-0.80mg/L, and 0.03-0.30mg/L with the enrichment factors of 29.26, 85.47 and 28.36, respectively for Malachite green, Crystal violet, and Rhodamine B. Limit of detections were between 2.2 and 5.1μg/L.