Green, fast and simple dispersive liquid-liquid microextraction method by using hydrophobic deep eutectic solvent for analysis of folic acid in fortified flour samples before liquid chromatography determination.

A fast, simple, sensitive, and efficient vortex-assisted dispersive liquid-liquid microextraction method (VA-DES-DLME) was developed based on hydrophobic deep eutectic solvent for extraction of folic acid from flour samples followed by HPLC determination. Hydrophobic DES was prepared by mixing amylalcohol as a hydrogen bond donor and methyltriocthylammonium chloride as a hydrogen bond acceptor. Factors affecting DLLME were considered and optimized. In optimal conditions, the calibration curve was linear in the range 5.0-500 ng g-1 with a correlation coefficient higher than 0.99. The limit of detection (LOD) and the limit of quantification (LOQ) were 1.0 and 3.0 ng g-1, respectively. The intra-day and inter-day precision at concentrations of 10 and 100 ng g-1 were less than 8%. Finally, application of the proposed procedure was investigated by folic acid analysis in flour samples and the relative recoveries obtained were acceptable (Recovery ≥ 90%).

Faraji M ，Mahmoodi-Maymand M ，Dastmalchi F 《-》

Determination of some red dyes in food samples using a hydrophobic deep eutectic solvent-based vortex assisted dispersive liquid-liquid microextraction coupled with high performance liquid chromatography.

Faraji M 《-》

A hydrophobic deep eutectic solvent based vortex-assisted liquid-liquid microextraction for the determination of formaldehyde from biological and indoor air samples by high performance liquid chromatography.

Hydrophobic deep eutectic solvents (DESs) are a new class of green solvents, and their research and application are a brand new area. So far, only a few hydrophobic DESs have been reported as extraction solvents. In this paper, five kinds of hydrophobic DESs composed of trioctylmethylammonium chloride and hydroquinone, 4-phenylphenol or 4-cyanophenol are designed and prepared for the first time. Melting point / glass transition temperature and density are also determined for these DESs. Coupled with HPLC, these hydrophobic DESs have been used as extractants in vortex-assisted liquid-liquid microextraction for the selective enrichment and indirect determination of formaldehyde. The optimization of reaction and extraction conditions, such as pH value, reaction time and temperature, concentration of 2,4-dinitrophenylhydrazine, type and dosage of the extraction solvent, speed and time of vortex, salt addition and centrifugation time are investigated in detail. It is found that under the optimized experimental conditions, the calibration curve of this method is linear in the range of 1.0-200.0 μg L-1 with the linear correlation coefficient (r2) of 0.9994. The limit of detection (S/N = 3) and limit of quantification (S/N = 10) are 0.2 μg L-1 and 1.0 μg L-1, and the intra-day and inter-day precision (RSD, n = 5) are 1.1% and 3.5%, respectively. The interference of some common coexisting ions and neutral molecules have been also tested. The proposed method has been successfully used for the determination of formaldehyde from biological and indoor air samples. The recovery of formaldehyde is in the range from 83.1% to 104.4%, and the relative standard deviation is lower than 5.9%. Furthermore, the analytical parameters of the proposed method have been compared with other extraction and microextraction methods.

Zhang K ，Liu C ，Li S ，Fan J ... -  《-》

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

Ge D ，Shan Z ，Pang T ，Lu X ，Wang B ... -  《-》

Liquid-liquid microextraction of synthetic pigments in beverages using a hydrophobic deep eutectic solvent.

A method was developed for the determination of eight synthetic pigments in beverage samples by liquid-liquid microextraction followed by high performance liquid chromatography. Using hydrophobic deep eutectic solvent (DES) as the microextraction solvent, several key parameters were optimized, including the type and volume of the hydrophobic DES, pH value, vortex time and salt content. Detection limits were in the range 0.016-1.12 ng/mL, recoveries were in the range 74.5-102.5% and relative standard deviations were <5.4%. The method is simple, green and practical, and could be applied to the extraction and determination of synthetic pigments in beverages.

Zhu S ，Zhou J ，Jia H ，Zhang H ... -  《-》