Natural thymol‐based ternary deep eutectic solvents: Application in air‐bubble assisted‐dispersive liquid‐liquid microextraction for the analysis of tetracyclines in water

Abstract

Four new thymol-based ternary deep eutectic solvents were prepared and evaluated as the extractive phase in air-bubbles assisted dispersive liquid-liquid microextraction for extraction of tetracycline, doxycycline, and oxytetracycline from the water before high-performance liquid chromatography. The maximum extraction efficiencies were obtained using 400 μL of [choline chloride]:[thymol]:[nonanoic acid] in the molar ratio of 1:2:2 at pH = 5. The solvent was characterized by FTIR and NMR spectroscopy. The hydrophobicity of the deep eutectic solvent and its effect on the pH of water samples after mixing was also studied. Besides, the extraction efficiency of the ternary deep eutectic solvent was compared with that of two binary thymol-based deep eutectic solvents, including [choline chloride]:[thymol] and [thymol]:[nonanoic acid] at the same conditions. Under optimal conditions, limits of detection and quantification were 1.2-8.0 and 3.8-26.6 μg/L, respectively. The linear ranges were 18.2-500 μg/L for oxytetracycline, 26.6-500 μg/L for tetracycline, and 3.8-500 μg/L for doxycycline with the determination coefficients > 0.9912. Intra-and inter-day relative standard deviations were 1.2-3.8 and 7.7-11.2%, respectively.The developed method was applied to the analysis of tetracyclines in unspiked and spiked environmental water samples, and the obtained recoveries were 74.5-95.4% with relative standard deviations of 1.2-4.0%.

Multifunctional Conductive Elastomers Based on Tannic Acid and Polymerizable 1-Butyl-3-methylimidazolium Chloride/Acrylic Acid Deep Eutectic Solvent

“…Therefore, the successful formation of DES can be confirmed by the change of the stretching vibration band of the O–H group in HBD, which may be related to the transfer of part of the portion of oxygen atom electron cloud to the hydrogen bond, resulting in the reduction of the force constant . As shown in Figure d, the absorption peak at 3036 cm –1 , related to the symmetrical stretching vibration of O–H of AA, was shifted to a low wavenumber of 2927 cm –1 in the BminCl/AA DES . The obvious shifts of the O–H stretching peak to lower wavenumbers suggest the formation of hydrogen bonds between BminCl and AA, which further confirmed the formation of the polymerizable BminCl/AA DES.…”

“…38 As shown in Figure 1d, the absorption peak at 3036 cm −1 , related to the symmetrical stretching vibration of O−H of AA, was shifted to a low wavenumber of 2927 cm −1 in the BminCl/AA DES. 39 The obvious shifts of the O−H stretching peak to lower wavenumbers suggest the formation of hydrogen bonds between BminCl and AA, which further confirmed the formation of the polymerizable BminCl/AA DES. The skeleton vibration of the imidazole ring at 1569 cm −1 can be observed in the DES spectrum, suggesting the successful introduction of BminCl into the DES.…”

Advances of responsive deep eutectic solvents and application in extraction and separation of bioactive compounds

“…These solvents are characterized by having a lower melting point compared to their individual components due to the charge delocalization that is contributed to the formation of hydrogen bonding [29,30]. The addition of a third component to the classical twocomponent DESs allows the density and viscosity of the ternary DES to be purposefully controlled, thus increasing the extraction yield [31][32][33]. Ternary DESs provide a new direction for improving the green extraction process and the extraction efficiency of natural active substances.…”

Development of deep eutectic solvent–based microwave‐assisted extraction combined with temperature controlled ionic liquid–based liquid phase microextraction for extraction of aflatoxins from cheese samples

“…In recent years, the utilization of green extraction solvents is of great importance. Room temperature ionic liquids (RTILs) [16] and deep eutectic solvents (DESs) [17] are considered as the new generation and green solvents that are widely used in the extraction processes instead of toxic organic solvents. Up to now, different DES-based extraction methods were developed during the analysis of various compounds such as chloromycetin and thiamphenicol [18], phytosterols [19], hormones [20], antibiotics [21], pesticides [22], tetracycline [23], etc., in dairy products.…”